[HN Gopher] DOE announces breakthrough in residential cold clima...
___________________________________________________________________
DOE announces breakthrough in residential cold climate heat pump
technology
Author : josephscott
Score : 571 points
Date : 2022-06-18 16:39 UTC (1 days ago)
(HTM) web link (www.energy.gov)
(TXT) w3m dump (www.energy.gov)
| anonu wrote:
| Can you use the same tech to cool a house? That would seem to be
| much more needed given the climate trends (warming) and
| demographic trends (moving to Southern US States).
| jamisteven wrote:
| "can save families as much as $500 a year on their utility
| bills".... ehhh, people affected by an extra 500 per year arent
| going to fork over 20k for a new system that will save only 500
| per year.
| gehsty wrote:
| Overall the cost may not be that much but the bigger shift is
| to electrification of heating instead of a gas burning boiler,
| as electrical systems can take advantage of power from offshore
| wind / solar etc. another way of looking at it is most people
| will replace their boilers in the next 20-30yrs, if they can
| get a electrical heat pump system they should (and the
| governments should make this economically advantageous to do
| so).
| hsbauauvhabzb wrote:
| Is the cost on new homes comparable? Does the US subsidise this
| at all?
| disantlor wrote:
| hmm as someone about to purchase a heat pump system for heat in a
| northern climate I am not sure if I should wait...
|
| is this an announcement of a breakthrough or a challenge to find
| a breakthrough?
| rudedogg wrote:
| If you haven't heard of it, make sure you use
| https://ashp.neep.org/#!/product_list/ to help pick a model.
|
| One tip from my install, is to go with single zone units. I did
| a multi-zone and the way the control system works is kind of
| weird. They also don't have as good of a turndown ratio[0] as
| smaller/single zone systems, making it less efficient.
|
| Overall I'm happy with it though.
|
| [0] https://en.wikipedia.org/wiki/Turndown_ratio
| zip1234 wrote:
| There are already heat pumps that work at very low temps.
| Mitsubishi has models that are still heating at -13f
| boulos wrote:
| FTA, they already measured it and will deploy in 2024:
|
| > The prototype delivers 100% heating at 5degF at double the
| efficiency, and 70% to 80% heating at -5degF and -10degF. DOE's
| Oak Ridge National Laboratory validated the performance and
| efficiency of Lennox's prototype.
|
| > Lennox is one of nine manufacturers competing in the CCHP
| Technology Challenge. Its product and others that meet the CCHP
| Technology Challenge will undergo trials in cold climate
| regions over the next two years to demonstrate performance,
| efficiency, and comfort when applied in the field throughout a
| winter. Deployment and commercialization are planned for 2024.
| Jgrubb wrote:
| I just bought a Mitsubishi mini split system to replace our oil
| furnace and bring A/C to our house here in New Jersey for the
| first time. Their high end outdoor units heat down to -13 F,
| which is colder than I've ever seen here. It arrives in august.
|
| Gree has a system that claims to have full heat down to -31, so
| I'd say just keep researching and you'll probably be fine.
| throw0101a wrote:
| > _Gree has a system that claims to have full heat down to
| -31, so I 'd say just keep researching and you'll probably be
| fine._
|
| Doing a quick search, they're using 'standard' R410A
| refrigerant (PDF):
|
| * https://www.greecomfort.com/assets/our-products/multi-
| plus-u...
|
| the same as everyone else. It seems just that they though it
| worth the engineering effort to push a little further than
| most other companies.
|
| See anything with the label "For Extreme Conditions":
|
| * https://www.greecomfort.com/our-products/
| david422 wrote:
| What is the plan for when it gets colder than -13? Do you do
| a hybrid with your furnace? Some other solution? Thinking of
| getting some heat pumps myself.
| leviathant wrote:
| In nearby Philadelphia, it rarely gets that cold, and not
| for extended periods of time, but when it does, we bust out
| blankets and space heaters to make up the difference.
| Jgrubb wrote:
| We usually switch to the wood stoves once winter sets in.
| Our forced air furnace is incapable of making the house
| warm and cozy because duct reasons that I can't really fix.
|
| I'm planning on getting rid of it altogether and doing the
| heat pump(s) most of the year, the wood stoves in winter
| and reclaiming a lot of headroom in the basement and an
| entire utility room that the furnace currently takes up.
| sokoloff wrote:
| I've looked into heat pumps pretty extensively for my
| upcoming boiler replacement (looking at an air-to-water in
| my case, but very similar principles apply).
|
| In my case, the 99% design temperature is high single
| digits Fahrenheit. For the 3.5 days/year colder than that,
| the plan is to have the house "coast" on thermal mass.
|
| That's for cases where the ambient temp is below design
| (where the heater can make heat but just no longer enough
| to keep up with the building heat loss), not for when it's
| below a cutoff (where the heater shuts off entirely). In my
| case, that's so far below design temp that I'd expect to
| never see it. (We hit -9degF in 2016 and would have to go
| all the way back to 1943 to find a low of -14degF.) If it
| happened, thermal mass would start to carry us with
| electric space heating keeping the house from totally
| freezing.
| hamandcheese wrote:
| I might invest in some backup propane heaters as well (a
| buddy heater at Walmart is pretty affordable and is safe
| for indoor use). I feel like in blizzard-like conditions
| having electricity be your backup plan might not be too
| wise.
| 0x53 wrote:
| They way it works in practice is that the air handler that
| comes with the heat pump will contain a backup emergency
| heat element in case it gets too cold or there is a problem
| with the heat pump. The cost to run it is much higher, but
| it should only run in the most extreme cold temperatures.
| newsclues wrote:
| Go ahead as planned but perhaps have the installer plan for a
| future upgrade when the current device fails
| mjmahone17 wrote:
| You probably should not wait: it will be 2 years of testing
| according to the announcement, and if you're doing a retrofit
| most the cost of installation will be installing the transfer
| lines inside, mounting the unit, etc (opening walls and closing
| them back up). Transferring from an old outdoor unit to a new
| one should be a fraction of the original install cost
| (basically just the new unit cost plus the cost of hooking it
| up).
|
| But, if you're willing to wait or pay extra for the efficiency
| gains, you might be even better off getting set up with a
| ground source heat pump now. The install cost is more up front,
| but because ground temperature is higher than air temperature
| in winter and lower than air temperature in summer, the
| differential you need to pump in or out is a lot less, and
| therefore much more efficient. I don't think any air to air
| heat pump in the next 20 years will be as efficient as a ground
| to air system you could install now. The air to air systems
| just have lower up front install costs.
| pbourke wrote:
| In the US, there is still a 30% federal tax credit for ground
| source heat pumps as well. Many of the other energy credits
| have sunset (such as solar, I think)
|
| Edit: it's 26% this year and 22% next year.
| selimnairb wrote:
| This doesn't sound any better than the efficiency of
| Mitsubishi/Trane "hyper heat" heat pumps, which are already on
| the market.
| tzs wrote:
| It depends on what they mean by this:
|
| > The prototype delivers 100% heating at 5degF at double the
| efficiency, and 70% to 80% heating at -5degF and -10degF. DOE's
| Oak Ridge National Laboratory validated the performance and
| efficiency of Lennox's prototype.
|
| Usually when people talk about efficiency of heat pumps they
| are comparing to electrical resistance heating (which is 100%
| efficient). If that's what they mean then they are saying 200%
| efficient at 5, which is not as good as Mitsubishi, which is
| better than 200% at 0.
|
| But in the first paragraph they say:
|
| > The U.S. Department of Energy (DOE) today announced that
| American heat pump manufacturer Lennox International became the
| first partner in the U.S. Department of Energy's (DOE's)
| Residential Cold Climate Heat Pump Technology Challenge to
| develop a next-generation electric heat pump that can more
| effectively heat homes in northern climates relative to today's
| models.
|
| It could be that they are stating efficiency compared to
| current heat pumps, not compared to resistance heating, in
| which case they would be claiming quite a bit higher efficiency
| than Mitsubishi, which would certainly justify calling it a
| breakthrough.
|
| Another possibility is that what they could be claiming as the
| breakthrough is the 100% heating at 5 part. The Mitsubishi cold
| weather heat pumps start losing capacity below 23, falling from
| 100% at 23 to 76% at -13.
|
| I don't think that would be as big a breakthrough as double the
| efficiency of current heat pumps, because it wouldn't make it
| so heat pumps are feasible in climates too cold for Mitsubishi.
| But it would make it so that in places you can use a heat pump
| you might not need as big of a heat pump with the new
| technology as you would need with a Mitsubishi. That could
| lower up front cost making converting from something else to a
| heat pump more feasible for many.
| joenathanone wrote:
| Domestic is the key here.
| adrianmonk wrote:
| Mitsubishi's products seem to be mini-split systems[1].
|
| _-- > EDIT: Or maybe not... they seem to offer forced-air too.
| <--_
|
| The DOE challenge is for ducted systems. Their site[2] says:
|
| > _The Challenge is currently focused on residential, centrally
| ducted, electric-only HPs._
|
| The DOE challenge also has other requirements[3] that I don't
| know if the Mitsubishi systems satisfy. It requires certain
| levels of efficiency and "grid interactivity" (meaning Energy
| Star "demand response"[4] where your utility can temporarily
| tweak your thermostat settings).
|
| ---
|
| [1] https://www.mitsubishicomfort.com/residential/new-products
|
| [2] https://www.energy.gov/eere/buildings/cchp-technology-
| challe...
|
| [3] https://www.energy.gov/sites/default/files/2021-10/bto-
| cchp-...
|
| [4]
| https://www.energystar.gov/sites/default/files/ENERGY%20STAR...
| R0b0t1 wrote:
| Kind of a shame, ducted heating has a lot of issues, but is
| the best for retrofit I guess.
| oneplane wrote:
| I wonder why ducted systems were part of the requirements, is
| it because it's just aimed at the USA and then mostly at
| adoptability for existing systems (which seems to be ducted
| mostly)? I only have anecdotal experience and no numbers to
| back that up, but it's the only reason I can come up with
| that would put such a restriction in place.
|
| I'd say rip the ducts out and just use split systems but I
| imagine other people have thought about that and figured it's
| not the best way to go. (or at last not in the US)
| pkulak wrote:
| Yes, because nearly every house in cold climates is ducted,
| and we're trying to get people off oil heating quickly,
| easily, and cheaply. Popping a new heat exchanger in an
| existing furnace is stupid simple compared to running
| coolant lines to new, wall-mounted exchangers all over the
| house.
| sokoloff wrote:
| Hydronic heat distribution (baseboard and radiators) is
| quite common in New England.
| TedDoesntTalk wrote:
| Not in any construction in the last 50 years.
| pkulak wrote:
| Sorry, meant to mean "in the US", since this was an
| American Government competition.
| sokoloff wrote:
| New England is part of the US.
| Gibbon1 wrote:
| I think that's true, if the ducts exist already that's
| simplest and cheapest. If they don't mini-split type
| systems are. But I suspect that long term those are going
| to be a pain in the butt because you have a lot of
| failure points.
| pbourke wrote:
| Mini splits seem to be pretty reliable. They're very
| common outside of North America. Most of the leading
| manufacturers seem to be from Japan (Mitsubishi, Fujitsu,
| Daikin)
| gwittel wrote:
| Many of the Mitsubishi heat pumps work with central ducted
| systems just fine. I have one (replaced a central gas heat,
| electric AC system). It's just a different air handler but
| the heat pump was the same as would have been used in a mini-
| split install.
|
| When cross shopping the Mitsubishi vs Trane, the Mitsubishi
| was miles ahead. I didn't even get the most cold weather
| efficient option (not needed for my climate).
| adrianmonk wrote:
| Oh, you must be right. I was finally able to find this on
| Mitsubishi's site:
|
| https://www.mitsubishicomfort.com/residential/products/duct
| e...
|
| And that says it's compatible with some "hyper-heat"
| outdoor units. So apparently they do offer both.
| philips wrote:
| How did you find a Mitsubishi installer? I like the product
| but couldn't find a contractor in the Portland Oregon area.
| gwittel wrote:
| I used Mitsubishis site to find the local "diamond"
| contractors (those factory trained and do enough volume).
| Then cross referenced vs yelp.
|
| https://www.mitsubishicomfort.com/find-a-contractor
|
| I see a few in Portland and several in nearby zip codes.
| Hopefully one can work for you. There are different tiers
| of "diamond" so you can compare if the difference matters
| to you.
|
| One thing that's a bit different is the air handler and
| outside compressor run on one circuit (mine is a 3 ton
| unit). So there's a power line between the 2 units. That
| threw off our city inspector. But it works out nice since
| I now have an extra 20A breaker free :)
| philips wrote:
| Thanks! Do you have the technical docs with the
| efficiency curves for the Mitsubishi ducted systems? I
| can't find the materials amongst all the marketing.
|
| For example this is the Carrier Infinity 24 we are
| considering. https://d1049ui2fjityy.cloudfront.net/userfi
| les/inriver/docu...
| gwittel wrote:
| I found it in their catalog. You'll need your model or
| series. After all the specs there were some
| efficiency/temp tables. It was under Pros (vs homeowner)
| -> USA -> product support -> catalog -> m and p series.
|
| Catalog:
|
| https://mylinkdrive.com/viewPdf?srcUrl=http://enter.mehva
| c.c...
|
| pocket guide:
|
| https://mylinkdrive.com/viewPdf?srcUrl=http://enter.mehva
| c.c...
| gwittel wrote:
| For reference, here's what we have: 36KBTU
| AIRHANDLER/HEATPUMP HI-STATIC M SERIES DUCTED SYSTEM
| INDOOR MOD# SVZ-KP36NA OUTDOOR MOD# SUZ-KA36NA2
|
| It's a slightly older model as we had height restrictions
| to work around. This prevented us from getting a newer or
| hyper heat model. IIRC ours had good efficiency into the
| 20F range which was plenty for us.
|
| In comparison, the Trane dropped efficiency at 50F and
| needed heat strips at that temp (so pretty crap).
| pfdietz wrote:
| I wonder if the ideas used here can make low temperature
| geothermal systems more efficient. An example is the 760 kW
| system at Chena Hot Springs, 50 miles east of Fairbanks, Alaska.
| The system there uses hot water from said springs to generate
| power using repurposed refrigeration technology.
| fghorow wrote:
| Chena Hot Springs geothermal _is_ a heat pump. It 's an
| absorption chiller used partially (primarily?) to keep an ice
| house chilled as a tourist attraction. It works for such
| relatively low geothermal temperatures because the average
| Carnot Delta T is pretty good (because Alaska).
|
| As to whether or not thermo-acoustic technology could work,
| that's a good question.
| markvdb wrote:
| So much air in this statement, but almost zero raw numbers.
|
| In the mean time, there are good quality air/water heat pumps on
| the market in Europe. Look at the Nibe F2120 for example. It
| blows this thing out of the water. It has a COP of 2.5 at -25C...
| gorbypark wrote:
| Any sources of info on good heat pumps in the European market?
| I just moved to Spain and am casually looking at options.
| [deleted]
| impostervt wrote:
| That's great news. I have a heat pump in my house, but still need
| to use the gas furnace when the temp drops below 40 degrees
| Fahrenheit.
|
| A repair person goofed the settings last January, and I didn't
| notice the furnace wasn't kicking in until the end of February.
| My electric bill went from $150-ish for Feb 2021 to $450-ish for
| Feb 2022.
| danans wrote:
| That's pretty poor performance. Most modern heat pumps on the
| market will work well below 32F, even at > 1 COP.
| happyopossum wrote:
| It's not about 'working', it's about the cost of electricity
| when it gets colder and the efficiency drops. Gas is pretty
| cheap for heating in most of the US...
| philips wrote:
| What heat pump do you have?
| dukeofdoom wrote:
| So 10k+ outlay to save under $500/year. That would take only 20+
| years to pay off. The wall units are kind of flimsy. Expect at
| least one to break. And that $500 in savings is probably
| $300/year in reality. Its still a great option for some places,
| just not really to switch over from a gas furnace.
| prirun wrote:
| Seems more reasonable to compare the typical initial cost vs
| the increased initial cost for the higher efficiency unit that
| saves $500/yr.
|
| My house was built in 2000 with a regular AC unit for the main
| floor and heat pump for the 2nd floor, both Payne, a builder
| grade of Carrier. The inside coil went first, at the 9-yr mark
| with a 10-yr warranty, so I did get a new coil at no expense
| but it cost $600 to install it.
|
| A couple years later, the outside heat pump went out, and
| because of the system's age (about 11 years), they recommended
| replacing the furnace and heat pump.
|
| A couple year later, the main floor furnace exhaust gas blower
| mechanism went out, and again, the outside unit was replaced
| because it was 14 years old.
|
| In contrast, my previous house had an American Standard AC and
| furnace that was installed in 1970 when the house was built. I
| had to replace the furnace blower motor one year - about $500 I
| think - but the original AC and furnace were working like a
| champ when I sold the house in 2003.
|
| In summary, you aren't getting 20 years out of any modern,
| shitty system anymore. They're designed to fail after 10 years.
| You might get lucky and have something fail after 9 years; then
| you'll only have to pay for labor. But because there are 2
| major independent components, the outside compressor and inside
| furnace, it's unlikely they'll both fail within the warranty.
|
| My AC guy told me the main reason they fail is because the new
| coils are made of very thin aluminum and so fail sooner than
| the old systems. If a coil fails, either in the furnace or the
| outside condenser, you're screwed. They can sometimes fix them,
| but good luck with that. Most HVAC dealers don't want to bother
| doing that; they just want to sell a new system.
| hgomersall wrote:
| Which is always the problem when you ignore the negative
| externalities. One would hope those externalities might start
| to be internalised to the cost of burning fossil fuels for
| heat, then heat pumps might become a better prospect.
|
| (Tbh, I recently did a high level analysis of a heat pump in a
| temperate climate, and in light of climbing fuel bills and the
| potential for low price electricity from renewables at low
| demand plus batteries, heat pumps start to make a lot of sense.
| You need to think about using them differently to gas though)
| bialpio wrote:
| I think it also ignores the fact that one of the big energy
| suppliers entered a war of territorial expansion and it may
| take a while until it's business as usual - I'd expect this
| to also affect energy prices.
| hgomersall wrote:
| Is this a US thing? Please elaborate...
| happyopossum wrote:
| Think it's pretty clear he's talking about Russia.
| hgomersall wrote:
| Whoops, yes! Evening responses are not my most alert
| time!
| kmax12 wrote:
| Interesting to see heat pumps come up more and more these days.
| As a lot of comments here point out, heat pump technology is
| already pretty good, even in cold climates.
|
| It seems to me a lot of the barriers to adoption in the US are
| lack of awareness from consumers and widespread support from
| installers. The equipment for a heat pump shouldn't be much more
| expensive then an air conditioner since they share so many parts,
| but that isn't the case in practice.
|
| I think government regulations that encourage heat pumps
| manufacturing and installation are part of the solution. For
| examples, Biden administration recently issued orders to use the
| Defense Production Act to produce heat pumps [0] or NYC banning
| new natural gas hook ups for heating [1].
|
| The other part of heat pumps adoption is making them exciting for
| consumers. It feels like if you get the right combo of all of
| that, heat pumps could be the next electric vehicle.
|
| I only recently learned about heat pumps and found it difficult
| to understand how they worked and potential benefits. Towards
| that end, I started hacking on this tool for others to get that
| info: https://www.heatpumpswork.com
|
| [0] https://www.whitehouse.gov/briefing-room/presidential-
| action...
|
| [1] https://www.theverge.com/2021/12/15/22837799/new-york-
| city-b...
| rocqua wrote:
| Reminds me of this company: https://www.blueheartenergy.com/
|
| The claims are pretty amazing. High efficiency, efficient over a
| wide range of temperature difference, high temperature
| differences possible.
|
| The operating principle is totally different. It is based on
| acoustic waves. Not using phase-changes but just the ideal gas
| law (pressure and temperature are proportional). I tried to get
| my head around it, and I got it with a standing sound wave. But
| they use a traveling wave, for which I could not find
| explanations I understood.
|
| The general idea is "lower air pressure and move gas to cold side
| so the gas heats up" followed by "raise air pressure and move gas
| to warm side so the gas cools down". That means the low pressure
| needs to be low enough that the gas gets colder than the cold
| side, and the high pressure needs to be high enough that the gas
| gets hotter than the hot side. Luckily that is 'just' a matter of
| amplitude of the sound wave. I think this is how they achieve
| their wide range of efficient temperature deltas.
|
| That wide range is the main difference with a phase-change based
| unit. The phase change happens at a much more difficult to change
| temperature.
| [deleted]
| lifty wrote:
| Really curious what kind of COP this technique can achieve.
| Cool tech if real, since it doesn't need any refrigerant.
| Wondering if there are other downsides.
| dr_dshiv wrote:
| Fascinating. I wish my physics courses had focused more on
| waves.
|
| https://en.wikipedia.org/wiki/Thermoacoustics
| honksillet wrote:
| When you get past freshman physics it is all waves! (Mostly)
| WJW wrote:
| All of it is also particles! (Mostly)
| dr_dshiv wrote:
| Wait, serious question, is a wave in water or on a string
| in some way also understood as a particle?
|
| And, even from the perspective of field theory, aren't
| fields defined by the type of waves moving through them?
| feet wrote:
| No, they're talking about things such as photons and
| electrons
|
| I don't think the fields are defined by their waves, but
| specific fields have specific wave patterns/types
| sjy wrote:
| https://en.wikipedia.org/wiki/Phonon
| jahnu wrote:
| Isn't it not all fields? (Mostly?)
| londons_explore wrote:
| Non phase change systems are inherently more efficient because
| every heat exchanger (air/air, air/coolant and coolant/water)
| can be counterflow, allowing substantially greater efficiency.
|
| In phase change systems, the 'hot side' and 'cold side' are all
| at the same temperature, which means any gradient in whatever
| you are heating/cooling is lost energy.
| pkaye wrote:
| This video shows how a thermoacoustic engine works. But I don't
| know if it can be good enough to cool an entire house.
|
| https://www.youtube.com/watch?v=abswNCqnMRQ
| jabl wrote:
| Another non-phase change method is the reverse Brayton cycle.
| Kind of like running a gas turbine in reverse. I think it is
| somewhat widely used in cryocooling, and in jet airliner cabin
| AC, but it seems to not have caught on for domestic heat pump
| applications. Presumably the traditional phase change
| approaches are more efficient in the relevant temperature
| ranges.
| rocqua wrote:
| Does this have something to do with vortex tubes?
| jabl wrote:
| No.
| thinkingkong wrote:
| This same mechanism is also how the james webb space telescope
| stays cold!
| digisign wrote:
| McJWS keeps the hot side hot, and the cold side cold.
| burnte wrote:
| Ooo, deep cut. I liked those burgers.
| babyshake wrote:
| > The general idea is "lower air pressure and move gas to cold
| side so the gas heats up" followed by "raise air pressure and
| move gas to warm side so the gas cools down".
|
| This sounds like Maxwell's Demon, where the work required to
| prevent the system from reaching thermodynamic equilibrium is
| equal to or greater than the extra energy. How does this differ
| from that?
| chroem- wrote:
| Energy input in the form of compressor work. It's not even
| remotely similar to Maxwell's Demon.
| SideburnsOfDoom wrote:
| This is how a refrigerator works. No it does not violate the
| "Maxwell's Demon" thought experiment. Yes it does consume
| electricity, it's not for free. _Efficiency_ gains are still
| good though.
| huffmsa wrote:
| Not at all. You use a compressor or some other means to
| increase the pressure. That's what the electricity is for.
| heavyset_go wrote:
| This isn't decreasing entropy without doing any work like in
| the thought experiment.
| numpad0 wrote:
| Counterarguments to Maxwell's Demon is not that such chambers
| with a microscopic door cannot be fabricated, but that the
| Demon and his door cannot run without some entropy/power
| source outside to the chamber thereby negating the "negative
| energy" created by it. The Demon works if you don't mind
| feeding him and maybe adding fuel to the chamber as well, but
| then you're not getting the supposed free energy.
| Dylan16807 wrote:
| Can you explain in more detail how it sounds like Maxwell's
| Demon? There's nothing that sounds like it sorts the air
| particles, so I don't see the connection.
| rocqua wrote:
| Maxwell says that the effort you put in is more than the work
| you can get out. So the heat difference you get, even if
| converted perfectly to other kinetic energy, will always be
| less than the electricity input.
|
| But we aren't after kinetic energy, or work. We are after
| heat.
| taeric wrote:
| I thought heat was a form of kinetic energy? Specifically,
| it is a measure of the kinetic energy of an object's
| particles, independent of the kinetic energy of the object
| as a whole. That not accurate?
| no-dr-onboard wrote:
| DOE should probably be capitalized as it's unlikely that a doe (a
| deer, a female deer. . .) came through with a technological
| breakthrough ;)
| RicoElectrico wrote:
| The opaque HN automatic title mangler doing its job. I'd argue
| it does more harm than good.
| libria wrote:
| We can't argue that until we have data on the true positives.
| For all we know, HALF the titles had the submitters pet word
| in all caps.
| mh- wrote:
| We could flag those.
| RicoElectrico wrote:
| How do we know? I did not notice such thing in original
| submission titles (as in <title></title>).
| dpcx wrote:
| I thought it was Doe-Anderson (a local ad agency) first... I am
| not a smart man without enough coffee.
| im3w1l wrote:
| This makes me idly wonder if we could use those rays of golden
| sun for heating more efficiently than we are. Pitch black
| panels facing the sun through which you pump some heat-transfer
| fluid? Hooked up to a heatpump?
| [deleted]
| nickpeterson wrote:
| One thing I do t see many mentioning is the low temp heat pumps
| currently available are pretty expensive last I checked (think
| $15k), that's simply not feasible for most people. We need
| something in the 4-8k range so the average joe can justify it.
| Perhaps this new set will be cheaper.
| Forge36 wrote:
| Where does the cost increase come from over an air conditioner?
| jhallenworld wrote:
| I just got a quote: $30K to upgrade a 1000 sq ft. apartment
| from oil fired steam (59% efficiency boiler from the 40s) and
| hot water to heat pumps near Boston. Includes removing oil
| tank, radiators and installing resistance electric hot water
| heater.
|
| Or I could upgrade from oil to gas for $14K (to an 82%
| efficiency boiler). I have a strong incentive to do this since
| the cost of heating with gas will be 1/3.5 compared with
| heating with oil.
|
| I think these are insane prices, but that's what contractors
| get around here. There is a $10K incentive for the heat pumps,
| but it requires a home inspection and probable upgrade of the
| insulation. IMHO, the incentive is not enough- it needs to make
| the heat pumps the cheapest option.
|
| As far as fuel costs, the gas would definitely be cheaper. The
| electricity comes from gas (especially in the middle of the
| winter). The price is more because you are paying someone to
| convert the gas to electricity. The efficiency of getting the
| heat from gas via electricity is only a little more with heat
| pumps (when accounting for generation and transmission loss and
| much higher heat pump efficiency).
|
| Maybe in the future the electric supply will be greener, but it
| isn't today. They are trying to build a HVDC line from Boston
| to Quebec for more hydropower, but Maine and NH are not
| allowing it due to NIMBY (a referendum in Maine, financed by
| gas companies, killed it).
| fortran77 wrote:
| The Technology Connections guy is going to be vindicated!
| pkulak wrote:
| Someone Tweet this at him, pronto!
| joemazerino wrote:
| Big news for us NorthEasters. Propane and oil are going up.
| endisneigh wrote:
| Cheapest thing to do is remove all exterior drywall, spray foam
| everything and call it a day.
| mh- wrote:
| Where do homes have "exterior drywall"?
| jeffbee wrote:
| I guess they meant demolish the interior finishes of exterior
| walls, spray foam the wall cavities.
|
| That's certainly a way to retrofit an older building, but you
| still need a heat pump.
| endisneigh wrote:
| You really don't. I've been in a house in Maine with spray
| foam in 20 degrees with no heat turned on and interior temp
| was around 65. It was pretty amazing actually.
|
| A heat pump isn't cost effective compared to Reno with
| spray foam. An average heat pump probably takes a decade
| minimum to pay off.
| mh- wrote:
| Ah, thanks. I get what they mean now. It doesn't sound like
| a good idea, but I get what they mean. :)
| t3rabytes wrote:
| drywall on the interior of exterior-facing walls
| [deleted]
| amluto wrote:
| Spray foam is expensive. It's considerably cheaper to install
| mineral wool or blown cellulose or fiberglass. And you can blow
| in insulation without removing the drywall.
| endisneigh wrote:
| Spray foam is expensive, but it pays for itself pretty
| easily. You can diy drywall hanging simply enough so you're
| really just paying for the foam and someone to plaster, you
| can paint yourself.
|
| A cheaper option is rigid foam with canned spray foam around
| the perimeter.
| mh- wrote:
| Aren't the tops of walls capped usually? How does one blow in
| insulation without removing drywall?
|
| Serious question.. I'd have thought it not practical to
| remove the cap on the wall (and that's assuming you can
| access it from the attic).
|
| edit: "top plate" is the term I couldn't remember. substitute
| for cap in my comment.
| magicalhippo wrote:
| > How does one blow in insulation without removing drywall?
|
| We got blown insulation in the floors (ie between roof and
| floor), he drilled a 2 inch hole every two feet or so. We
| added our parquet floor right on top, with just some thin
| XPS sheets inbetween for noise.
|
| Not sure about drywall, but I'd imagine it's similar.
| Easiest would be to just put some 6mm plasterboards on top
| to cover the holes, saves you handling each one
| individually.
| amluto wrote:
| You drill smallish holes in the drywall in each stud bay,
| blow the insulation in through the holes, and patch them.
| This is much less expensive and less messy than removing
| and replacing drywall. It can be done with cellulose
| insulation, with fiberglass (the loose fluffy kind, not
| batts), and possibly some other products.
| mh- wrote:
| Ah ok that makes sense. Thanks!
| beepy wrote:
| "Lennox International... developed the first prototype that
| achieved the Technology Challenge's standards about a year ahead
| of schedule. The prototype delivers 100% heating at 5degF at
| double the efficiency, and 70% to 80% heating at -5degF and
| -10degF."
|
| The release goes on to say they expect commercialization and
| deployment in 2024.
| tempestn wrote:
| Perhaps I missed it skimming the article, but my question is,
| double the efficiency compared to what? To the current state of
| the art cold climate hear pump? Or to a resistive heater?
| pkulak wrote:
| Yeah, and what is "100% heating"? Do they mean 100% of the
| capacity? Why do people write things with important words
| just left out?
|
| My new car can do 100% driving!
| yason wrote:
| What they probably meant is that at 5degF the pump can
| supply 100% of the heat required to keep a house (of
| certain size) warm, with no other form of heating required.
| At -5 and -10, it can still extract enough heat from the
| outside to supply 70-80% of what's needed but you will need
| other means of heating such as resistive electric radiators
| to complement the heat pump.
|
| Surely not engineering way of thinking but that's a common
| heat pump metric for ordinary people.
| joemazerino wrote:
| To the current cold pump which can only be efficient at 0 or
| above. Then you get diminshing returns for the electricity
| expenditure
| 2OEH8eoCRo0 wrote:
| Heat pumps have efficiency > 100%
| OJFord wrote:
| No they don't. Just because you don't pay for an input
| (outside air/the ground/a body of water) doesn't mean it
| isn't an input.
| lupire wrote:
| Efficiency is a misleading word for heating, because the
| units don't match; they are both energy, but different
| "type". The denominator is fuel energy lost, but the
| numerator is thermal energy change within an area of
| interest. A heat pump moves thermal energy from outside,
| changing unimportant thermal energy into good thermal
| energy.
|
| "Coefficient of performance" is a better term.
|
| https://en.m.wikipedia.org/wiki/Coefficient_of_performance
| stormbrew wrote:
| This just seems like unnecessary hair splitting to me.
| Obviously the efficiency of something is subject to the
| important inputs and outputs involved.
|
| If someone asks: "how efficient is this heat pump at
| heating my house?" And you start digressing about how
| that's the wrong question to ask you'll be giving them an
| impression opposite reality, which is for most people: it
| will use less electric energy than heat energy it puts
| into your house, almost all the time.
| hedora wrote:
| There are theoretical upper bounds on the COP though. As
| heat pumps get better, it may some day make sense to say
| things like "this heat pump is 95% efficient, so there is
| no point in replacing it".
| ketzo wrote:
| Huh, I've always heard the "heat pump efficiency > 100%"
| but never really understood what that meant. Thanks for
| the explanation.
|
| So the ">100%" comes from the fact that you're spending
| less thermal energy than you are moving?
| thedougd wrote:
| Exactly.
| dghughes wrote:
| No OP but yeah heat pumps are very efficient some >300%
| efficient since you're just "pumping heat" from one place
| to another not generating it.
|
| Even electric heat alone is 100% efficient no incomplete
| combustion or degradation over time. Efficient bu much
| more expensive than just moving heat already in the air.
|
| Ground-source are better for now since they are moving
| heat from a relatively consistent source the Earth. It's
| about 15C to 25C one meter down where the ground-source
| heat pump lines are run.
|
| Generating vs moving heat I think is misunderstood by
| people or really more likely they just don't care. As
| long as the bill is low!
| based69 wrote:
| If you could really move heat 300% more efficiently than
| using a resistive heater to generate heat, couldn't you
| just move a bunch of heat to power a steam turbine and
| get a perpetual motion machine?
| pbhjpbhj wrote:
| It's not entirely clear what you mean. But, you say "if
| you could really ..." as if ground-source/air-source heat
| pumps don't do this exact thing; do you think they don't
| work?
|
| Running a steam turbine by pushing water down a borehole
| to come into contact with a high-temp (>100degC) source
| has been done; it's not perpetual motion. Energy pumping
| the water is << energy output from the steam produced.
| It's solar energy that's being used, ultimately.
| Gibbon1 wrote:
| Yeah take the energy you pump from Reservoir A to
| Reservoir B divided by the energy requires to do that and
| that's COP. Which you can think of as an efficiency.
| PaulDavisThe1st wrote:
| Slightly more precisely: you're using less energy (in the
| form of electricity used to run the heat pump) than you
| are moving into/out of the heated/cooled space.
| martijnvds wrote:
| Maybe they're trying to write around the term "Coefficient of
| performance" (COP) for people who have never heard of heat
| pumps.
|
| I think a COP of 2 at 5degF (-15degC) is pretty good.
| tssva wrote:
| Minimum COP for the competition is 2.1-2.4 at 5degF. No
| idea what the actual COP for this unit are.
| linsomniac wrote:
| COP of 2 at 5F is good. But... Mitsubishi has one that is
| 3.13 at 5F and LG has one at 2.65 at 5F, so this isn't
| really the breakthrough that the press release claims, the
| breakthrough is that a US company is doing it.
| tssva wrote:
| That depends on whether the Mitsubishi and LG units meet
| the other requirements of the competition.
| mikewarot wrote:
| At some point, it would be great to use a natural gas powered
| engine to run a heat pump. You could then use the exhaust gas as
| a heat source for the heat pump, possibly eliminating the need
| for a pre-heater.
|
| Cooling the output should increase the Carnot efficiency of the
| motor.
|
| Heating the outside air intake with that heat should be
| sufficient to avoid the need for an electrical resistance pre-
| heater.
|
| This combination could also run on propane, ethanol, gasified
| wood, etc. Anything that gets burned now could be used to create
| far more heat output than straight up combustion.
|
| There's got to be a flaw in this idea, math/physics wise.
| threeseed wrote:
| > There's got to be a flaw in this idea
|
| The flaw is that we need to stop using fossil fuels now in
| order to meet Paris targets.
|
| Natural gas in particular is an issue because demand is
| increasing globally whilst large suppliers i.e. Russia,
| Australia for many reasons are not able to meet it. Which is
| pushing up prices and increasing unreliability over the short,
| medium and long term.
|
| Now is the best time to bite the bullet and transition to a
| decarbonised world.
| [deleted]
| lazide wrote:
| I think you're basically describing a steam engine that
| mechanically powers a heat pump, pumping it's own waste heat
| and whatever environmental heat it needs.
|
| It's pretty complicated. Direct hearing via heat exchanger is
| usually pretty good and much simpler, albeit less efficient. If
| burning thermal sources, raw efficiency is rarely all that
| necessary though. The heat output per unit mass is usually
| pretty high.
| speedgoose wrote:
| > There's got to be a flaw in this idea
|
| Environmental impact or geopolitics issues aside, an
| electricity grid is much more convenient and cheaper than a
| propane/ethanol/gasified wood grid. Transporting gaz by trucks
| and storing it in individual houses is not very convenient too.
| cmarschner wrote:
| Why would you create new technology with natural gas these
| days. It seems such an energy source of the past. Europe is jus
| suffering from the dependency on it and seeks to get away from
| it as soon as possible.
| finiteseries wrote:
| Europe is resource poor and suffering from a dependency on
| Russia.
|
| 55 billion cubic meters annually were set to be added to this
| dependency as recently as February 21st of this year before
| yet another land war erupted on the continent, forcing them
| to _suspend_ certification.
|
| The pipeline is already built though.
| Someone1234 wrote:
| Agreed. Just electrify everything in the home, then while we
| still have natural gas then just use it for electricity
| generation. Natural gas's only benefit is that it is
| currently cheap, when that stops being true, then it is just
| worse than electricity across the board.
|
| The great thing about electricity is that it scales REALLY
| well with new generation and distribution technologies.
| petesergeant wrote:
| I'd rather cook on a gas hob than an electric one at the
| moment
| threeseed wrote:
| You may change your mind when it becomes orders of
| magnitude more expensive.
| coryrc wrote:
| I use single dollars a month in gas cooking.
| bonzini wrote:
| Infrared absolutely, but induction cooktops are pretty
| good and the only thing you can't do with them is stir
| frying.
| philips wrote:
| Why can't you stir fry?
| liveoneggs wrote:
| You can't remove or move the pan during cooking
| dd36 wrote:
| You can for a few seconds.
| coryrc wrote:
| So, you burn natural gas in a powerplant to create
| electricity somewhere around 55% (hopefully) efficiency; in
| most of the US, the heat output is wasted. You then lose 6%
| to transmission, getting to 52% efficiency, to put it into
| a 2x COP heat pump (which we mandate use gases with GWP in
| the thousands) to get 104% of natural gas heating.
|
| Or, spend the same amount on air sealing reducing heating
| needs by about 30%, pay workers instead of factories, and
| get the same reduction in natural gas use, also without the
| refrigerant bomb waiting to go off, and not needing more
| power plants built. Mandate every rental have lower than 6
| ACH50, since misaligned incentives mean they're usually
| worse than homeowner-occupied units.
| seoaeu wrote:
| Efficiency percentages are the wrong way to look at it.
| If you instead frame it in terms of tons CO2 equivalent,
| then locking in the emissions every year between now and
| 2050 is going to be worse, compared to the alternative of
| burning a bunch of natural gas for electricity now but
| gradually phasing it out in favor of wind and solar.
| coryrc wrote:
| Most heat pumps aren't going to last 30 years. Passivhaus
| only needs 1500W maximum of heating, so they usually
| don't use heat pumps.
|
| Wind and solar also lock in natural gas usage, because
| they don't provide inter-seasonal storage or even intra-
| day storage.
| [deleted]
| 10u152 wrote:
| These certainly exist and have some, rare use cases.
|
| Personally I've seen them use when there are large air
| conditioning loads but insufficient electrical power
|
| https://www.yanmar.com/global/energy/ghp/
| smileysteve wrote:
| When I read the title, I wonder why air to water and air to
| ground heat pumps aren't more common in cold climates. Where it
| is 0degf on the surface, a few feet deep and you're back to
| 46degf.
|
| So we could have had efficiency 10 years ago instead of today?
| jltsiren wrote:
| Ground source heat pumps have become popular in the past 10-20
| years. Natural gas has historically been cheap enough that
| replacing it may not be cost-effective if your house is
| connected to a gas grid. When replacing other heating sources,
| a ground source heat pump typically pays itself back in 5-10
| years.
| zdragnar wrote:
| Most homes with natural gas don't have enough space for a
| horizontal system, and vertical systems are very cost
| prohibitive.
|
| When you do have land, your horizontal space now is also
| being used up by a septic system.
|
| It's great if you can do it, but on the whole I suspect
| ground source is always going to be an expensive and
| difficult proposition for most people.
| jltsiren wrote:
| Based on a quick search, the typical costs for installing a
| vertical system to a single-family home are 15k to 25k
| euros in Finland. The contractors I found seem to
| discourage horizontal installations unless the bedrock is
| unusually deep. Drilling bedrock is cheap, while horizontal
| pipes have to be much longer, because the ground gets cold
| in the winter.
| zdragnar wrote:
| Odd, here drilling far eclipses excavation costs.
| Horizontal systems just need a backhoe to install, as you
| only need to dig below the frost line (we also get down
| to about -40 in winter). Vertical drilling requires more
| specialized equipment and so is more costly. Vertical
| systems are about $10k more expensive than higher end
| horizontal systems.
| pbourke wrote:
| Ground source heat pumps are 2-3x the cost of air source, and
| require a decent sized piece of land for installing the ground
| loop. Vertical installations use less surface area but are even
| more expensive since you're drilling holes 400' deep for the
| loop.
|
| Water source heat pumps are easier installations but require
| houses sited near a specific type of fresh water source that
| does not fully ice over in the winter or dry up in the summer.
| hinkley wrote:
| Any studies in what these things do to the frostline?
|
| Heat pump is better than burning fossil fuels, but we also
| stop needing to treat system after system like it's a
| bottomless well. We did that with real wells, then rivers,
| then the sky, then the ocean, then carbon dioxide and next up
| will be ground heat.
|
| There was a house last year that I think people were
| complaining about on Reddit, giant house out I'm the woods,
| all glass walls and heat pumps, labeled as green. It's not a
| green building if you are 2x as efficient as fossil fuels but
| your house needs four times the BTUs of a reasonable design
| and 6 times a green one.
|
| Twice as efficient and half the heat loss is green. Blowing
| the surplus is not.
| starkd wrote:
| Once again the headline does not match the claim in the article.
| This is not a breakthrough in terms of technology. This is the
| announcement of a partnership. There was no "breakthrough". This
| is government advertising for a private sector company that
| frankly is beginning to resemble corporate fascism.
| dchichkov wrote:
| There is plenty of opportunity in being more efficient. To give
| an example, houses in the Bay Area has gray/black roofs. In the
| summer such roof receives about 10kW of energy and readily
| converts it into heat. Heat, which we are trying to evacuate from
| the house with our super-efficient heat pumps in the air-
| conditioning units.
|
| If only we'd painted these roofs with white reflective roof paint
| (~92% reflection). We would have removed ~8kW of heating from
| such roofs! And then, maybe, we wouldn't have to pump all that
| energy into air-conditioning. So the surrounding air would be
| cooler, less noise would be heard from air conditioning, less
| energy would be spent. And the cost? 4 gallons of white
| reflective paint and a couple of hours of work, painting the
| roof...
| drusepth wrote:
| What happens to the "heat" energy that gets reflected by
| white/reflective roofs? It seems like it'd stay in the relative
| vicinity of the house, heating up the outside air further (even
| by a small amount), right? If that's the case, are there
| diminishing returns to worry about with effectively just moving
| heat from one place to another, assuming the (hotter) outside
| air will probably continue to warm up the house anyway? Do we
| just bank on something else absorbing the energy instead? Does
| it leave the area/atmosphere if nothing absorbs it?
|
| (Please don't take this as a rhetorical "this is why X solution
| doesn't work" -- I'm no expert here and am just curious where
| all that reflected heat/energy goes!)
| jliptzin wrote:
| I would assume those light rays reflect off the roof instead
| of getting absorbed...in that case the heat is absorbed into
| the atmosphere, I have a hard time believing it sits around
| the house and lingers there for any significant amount of
| time (doesn't heat rise?)
| oneoff786 wrote:
| Heat rises is short for hot air rises. The light would not
| be completely absorbed by the atmosphere more than it did
| on the way down.
| extra88 wrote:
| With a light or reflective surface, a lot of the energy is
| reflected as light so it's not converted to heat. Relatively
| little will be absorbed by the air near ground level, heating
| the air only a little.
| dexwiz wrote:
| "Heat" from the sun that we feel is mostly IR/Visible light.
| Mix of stuff happens if we reflect it with white surfaces.
| Some of it does go back into space. Some of it will get
| reflected by the atmosphere back towards the ground. IR light
| is also directly absorbed by the air molecules, but very
| little. Air is mostly transparent at visible wavelengths so
| it absorbs very little energy. Solids are much better at
| converting IR to thermal energy. Realistically air
| conditioning is just moving heat from one side of a wall to
| another. Overall painting buildings white won't change the
| temperature of Earth, but it does help the building in
| question, which is all air conditioning cares about anyways.
| myself248 wrote:
| All that energy started at the sun, we call it "light" when
| it's visible and "radiation" when it's outside our visual
| range, but it's the same stuff.
|
| The fact that it reached the roof in the first place means
| the atmosphere is transparent to it. So with a white roof,
| the wavelengths being reflected are the same ones being
| received, it'll reflect right back through the atmosphere and
| back into space. Effectively it just increases the Earth's
| albedo a tiny bit.
|
| Any wavelengths which were gonna heat the air by absorption,
| were absorbed on the way in and didn't reach the roof in the
| first place.
|
| HOWEVER.
|
| In the case of dark/black roofs, the heat DOES stay in the
| vicinity of the house, at least for a while. The radiation
| was absorbed by the roof, and now two main things happen to
| it:
|
| One, the hot roof heats the nearby air by convection. This is
| the main contributor to the "urban heat island" effect.
| Eventually this warmed air mass will affect weather patterns,
| but even before that, it just makes the place feel hot.
|
| Two, the hot roof emits its own radiation, in a whole range
| of wavelengths determined by its absolute temperature,
| according to Planck's law. This includes infrared wavelengths
| that the atmosphere is not transparent to (the absorption
| region between 5 and 8 microns), so that radiation IS
| absorbed by the atmosphere and heats it as well. And just
| like convective transfer above, the warmed air contributes to
| heat-island and weather effects, etc.
|
| (The phenomenon of a hot object emitting its own radiation is
| why thermal cameras work, by the way. And if you get the
| object even hotter, the Planckian locus shifts into our
| visible range and you get an object that is "red hot", or
| even hotter still and it's "white hot", etc. This is why the
| "whiteness" of lightbulbs is expressed in Kelvin, that's the
| temperature of an object that would glow the same color as
| the bulb emits. The "warm white" and "cool white" are
| misnomers; the so-called "cool" color represents a much
| hotter blackbody source.)
| grog454 wrote:
| > Any wavelengths which were gonna heat the air by
| absorption, were absorbed on the way in and didn't reach
| the roof in the first place.
|
| What is the basis for this? Intuitively (I am no expert) it
| seems more likely that the amount of thermal energy
| produced would be a function of the distance light travels
| through a medium and the amount of energy carried by the
| light in the first place. So I would expect that the
| "inbound" light would produce more thermal absorption
| energy than the reflected "outbound" light, but it wouldn't
| arbitrarily _all_ be absorbed on the way in.
|
| Reality seems to be more complicated: https://www.sciencedi
| rect.com/science/article/abs/pii/096016...
| myself248 wrote:
| It was a bit of an oversimplification on my part, since
| for a given wavelength, the atmosphere isn't binary,
| completely transparent or completely opaque (i.e. the
| radiation would go a very very short distance before
| being absorbed), but for _most_ wavelengths it's _very
| close_ to binary. Either it's absorbed or it isn't, to a
| first approximation.
|
| Yes, some wavelengths are absorbed very weakly, and some
| are scattered rather than absorbed. But these represent a
| tiny fraction of the spectrum, the nuance would've
| overcomplicated the post, and they don't change the
| result much.
|
| For wavelengths that are not absorbed, they can be
| reflected back out just as easily as they came in. For
| wavelengths that're strongly absorbed, they heat the
| first parts of the atmosphere they encounter, and this is
| why the thermosphere is called that.
|
| For those few wavelengths that're weakly absorbed, yes
| they produce some heating on the way in, and if you
| reflect them back out, they do produce some heating on
| the way out. But as you've said, because the intensity of
| the radiation is decreasing along the whole path, the
| "outbound" contribution is weak indeed. It turns out to
| be basically a rounding-error in the thermal
| contribution, which is overwhelmingly dominated by
| blackbody absorption and re-emission, which often does
| produce wavelengths that're strongly absorbed. On a
| perfectly-white planet (or snow-covered region), you
| might have to start caring about weakly-absorbed
| wavelengths, but for most types of ground cover, other
| effects swamp it.
| rayiner wrote:
| Would that work in terms of all the other stuff? Rain snow etc.
| [deleted]
| recuter wrote:
| Imagine instead of paint if we could come up with some sort of
| material that generates electricity.
|
| P.S. - If you look into the white paint thing more carefully
| you'll be rather disappointed.
| mumblemumble wrote:
| I have photovoltaics on my roof. I won't be doing it again.
|
| I'm almost certain that putting the money that they cost into
| making my home more efficient in the first place, by doing
| things like sealing leaks, upgrading the insulation, and,
| yes, making the roof a lighter color, would have reduced our
| energy consumption by more than the amount that the PVs are
| generating.
|
| The PVs absorb a lot of thermal energy, too, more than the
| shingles themselves do. So they make the roof hot. You can
| actually feel the difference inside the house - the rooms
| that are underneath the solar panels get warmer in the summer
| than the ones that aren't. So some amount of that electricity
| we're generating would seem to just be undoing the effects of
| the PVs on the house's thermal situation. There's still a net
| benefit, but probably because we're people who are inclined
| to accept that summer is hot in the first place. Trying to
| keep those rooms at or below 80F/26C might be an expensive
| endeavor.
|
| Also, I've discovered that one does not simply have a roof
| leak fixed when there are solar panels on the roof, because
| they are in the way. So maintenance has been rather more
| expensive than I expected.
|
| In general, I'm sanguine about solar as a renewable option.
| I'm just increasingly inclined to believe it's better
| implemented as an industrial technology, and that homeowners
| probably have better options for greening their houses.
| Angostura wrote:
| Interesting. My PVs have made the house substantially
| cooler. There is an air gap between the panels and the roof
| itself - they effectively shade the roof.
| mumblemumble wrote:
| Aha. Well, I would not be at all surprised to discover
| that we ended up with a sub-par installation.
| throwaway3334 wrote:
| Are these solar tiles (solar shingles) or a traditional
| air-gaped panel?
| dd36 wrote:
| Same. This statement is bizarre to me. You can't bolt
| solar panels directly to a roof. There is an air gap from
| the rails and also the edges of the panels.
| zie wrote:
| You actually can if you get the stick on variety. They
| don't last as long, etc, etc. But they do exist and have
| their uses.
| JaggerFoo wrote:
| I came across a forum thread for Baja California, where
| thay have and discuss off-grid air conditioning in a very
| hot area of Mexico. Interesting discussion.
|
| Air Conditioning Off The Grid:
| http://forums.bajanomad.com/viewthread.php?tid=97584
| grog454 wrote:
| > The PVs absorb a lot of thermal energy, too, more than
| the shingles themselves do.
|
| I've found this to be interesting going back as far as
| middle school, where we're taught renewable energy sources
| like solar panels can help reduce global warming by
| replacing greenhouse gas emitting alternatives. Yet
| fundamentally, they are designed to turn the only external
| source of energy our planet receives (sun light) into heat
| and other forms of energy that will eventually become heat
| rather than reflecting it back out into space (albeit
| through the atmosphere). Seems so backwards to me.
| mumblemumble wrote:
| One could argue that the only energy sources that aren't
| doing this somehow are geothermal and nuclear.
| stephen_g wrote:
| That's not correct - nuclear power plants only have
| efficiencies of about 33-37%, so 63 to 67% of the energy
| that nuclear reaction is producing is dumped into the
| atmosphere which wouldn't have otherwise (obviously there
| would have otherwise still been some radioactive decay of
| the material in the ground if it wasn't used as nuclear
| fuel, but nothing like refining it and bringing it to a
| critical mass in a reactor).
|
| Meanwhile, 100% of the energy that a solar panel receives
| (and radiates some back as heat) would have hit the earth
| anyway.
| stormbrew wrote:
| The problem we're trying, broadly, to solve right now
| isn't "we're directly heating up the planet" but "we're
| trying to stop trapping heat in the atmosphere through a
| potentially self-propagating greenhouse process".
|
| This is why carbon neutrality is the focus and not just
| purely energy usage.
| grog454 wrote:
| It appears to be a different (and more direct) way of
| framing the same problem:
| https://www.nasa.gov/feature/langley/joint-nasa-noaa-
| study-f...
|
| A better argument for solar panels is that per kwh of
| useful energy, a solar panel traps less solar energy (in
| kwh) than the CO2 produced by coal or gas or w/e. But
| I've never see this particular argument made and
| therefore couldn't even guess at HOW much better a solar
| panel is than coal and HOW much worse it is than nuclear
| or geothermal (which could actually be net energy loss
| for earth, by dispersing some thermal energy locked deep
| within the earth out to space).
| [deleted]
| stormbrew wrote:
| > A better argument for solar panels is that per kwh of
| useful energy, a solar panel traps less solar energy (in
| kwh) than the CO2 produced by coal or gas or w/e.
|
| It's not a better argument because the solar panel
| doesn't "trap" the energy. At most it borrows it,
| eventually it will radiate back out if allowed to do so,
| just as it would if it were absorbed by a rock. Humans do
| not occupy enough of the surface of this planet to make a
| dent in that.
|
| The thing that will keep it from radiating back out is
| greenhouse gases in the atmosphere. And unlike some brief
| capture of energy, the greenhouse cycle is essentially a
| chain reaction.
| MichaelZuo wrote:
| But it is radiating it 'back out' less efficiently than a
| white roof. Thus black solar panels may indeed be a net
| negative if every building otherwise would have had a
| white roof.
|
| In a land of mostly dark roofs it's probably a net
| positive.
| stormbrew wrote:
| Unless you pump the energy deep in to the ground it will
| still eventually find its way to radiate back out in the
| form of infrared blackbody radiation. The timescale we're
| talking about isn't very long in the grand scheme of
| things, and the entire surface of the planet is doing
| this to some extent or another.
|
| Even if we did one of those megasolar projects people
| like to talk about like paneling the whole Sahara or
| Mojave, we would still only be absorbing a tiny amount of
| the petawatts per second the sun is constantly bombarding
| the planet with, much of it being absorbed by plants, the
| ocean, darker rocks, etc.
|
| Our solar panels just don't hit the scale that the
| melting ice caps do, and the only thing we can do to stop
| that is reduce the flow of new ghgs into the atmosphere.
| [deleted]
| ericd wrote:
| Yeah, it's a little counterintuitive, I'd just keep in
| mind that the amount of energy we use is _tiny_ compared
| to the amount that the sun bombards the earth with. The
| absorption and generation is going to be insignificant
| compared to the amount trapped by the addutional
| greenhouse gasses.
| stephen_g wrote:
| That doesn't follow. Consider the alternatives - thermal
| generation (including nuclear) must reject massive
| amounts of waste heat into the atmosphere, before the
| electricity is used and heat is generated from that use.
| That's what cooling towers are designed to do.
|
| That's even before thinking about the effect from CO2 or
| methane from gas fugitive emissions.
|
| The earth has the ability to radiate away quite
| considerable amounts of heat luckily, and solar produces
| considerably less waste heat than thermal. So solar and
| wind can only make things better.
|
| Minimising waste heat is of course good, which is why
| energy efficiency is so important, and heat pumps are
| doubly so - because they are extremely efficient, but
| also because they don't produce as much heat but transfer
| most of it!
| XorNot wrote:
| What do you think normally happens to the 1000w per
| square meter which the sun radiates?
| sacrosancty wrote:
| More of it is reflect back into space from many natural
| surfaces than from solar panels. Not scientific but look
| how black this solar farm appears compared to the
| surrounding land
|
| https://eoimages.gsfc.nasa.gov/images/imagerecords/85000/
| 854...
| XorNot wrote:
| Right and so to follow this logic through, how do you
| think we get energy out of fossil fuels? Or nuclear
| reactors? Or a hypothetical fusion power plant?
| coryrc wrote:
| I doubt that picture is recording most of the wavelengths
| of light responsible for getting heat back into space.
| enraged_camel wrote:
| >> The PVs absorb a lot of thermal energy, too, more than
| the shingles themselves do. So they make the roof hot. You
| can actually feel the difference inside the house - the
| rooms that are underneath the solar panels get warmer in
| the summer than the ones that aren't.
|
| I've actually read the opposite: most PVs don't sit
| directly on the roof, but rather a few inches above it. And
| that air gap further limits the amount of solar energy that
| makes it onto the roof and into the attic.
| XorNot wrote:
| That claim doesn't really add up. I have solar panels as
| well and yes - not only is their an air gap, but pretty
| obviously the rooms they're over are north facing (I'm in
| Australia) with north facing windows and obviously get
| hotter anyway due to that.
| supernovae wrote:
| Are you in a mobile home or something?? I have solar too
| and I absolutely love it. I'm not sure how anyone could
| feel warmer in a room with panels above as i've never seen
| a stick house without attic spaces and i've used my IR
| camera to look for hot spots and i see nothing out of the
| normal where any panels are... also, panels tend to cover
| the entire surface area where the sun is shining the most
| too not just rooms so it makes no sense to me read what
| you're saying.
|
| To make solar worthwhile we did an energy audit so we also
| replaced windows, got new siding and installed new doors.
| Energy efficiency doesn't have to be mutually exclusive. I
| got a bigger rebate from the city with proof of energy
| audit.
|
| as far as roof repairs... why would solar matter and why so
| many roof repairs? I've been through tropical storms, down
| pours and many a hail storm and not a single problem and my
| roof is 23 years old..
|
| I could never go back. I charge my Tesla at home and my
| electric bill averages about 70 a month over a year after
| solar. That's less than a weeks worth of gas for my Jeep.
|
| year 6 on panels and 0 maintenance with a 20 year guarantee
| on efficiency and install warranty if i had problems i'd
| call my installer for service.
| fomine3 wrote:
| Solar panels are placed on best places to receive solar
| emission, so the room also be hot, isn't it?
| tomrod wrote:
| Is this not something simple foam insulation would fix?
| highwaylights wrote:
| Wouldn't a reflective coating work better?
|
| Given it's a once off cost it seems like this should be
| doable.
| thombat wrote:
| Neighbors and pilots may complain
| highwaylights wrote:
| I dislike people and planes are noisy.
|
| I take your point, I'm doing it anyway.
| throwaway3334 wrote:
| Actually, I was looking into installing solar, to offset
| $400/month of air-conditioning costs, during the summer. I
| could have had around 1.5kW of solar. But the cost of this is
| north of $25k, plus all the hassle to get the permits, plus
| all the extra complexity. While the cost of painting the roof
| is $100 + work. And now it is very rare that I have to run
| the AC.
| sxates wrote:
| Do you mean 15kw? 1.5 is only like 4 panels, it wouldn't
| make $400 per month and wouldn't cost anywhere near $25k.
| throwaway3334 wrote:
| I was looking at installing a very small solar array,
| just to offset the AC costs. The quote for the solar kit
| that could produce ~1.5kW (2170W Solar Kit: 7xURE NSP
| 310W - Mono 60 Cell - All Black Panels + 7xEnphase IQ7
| 60-Cell Microinverters w/QCables + 1x Enphase IQ Combiner
| 3 + Wireless Monitoring) was $6.5k.
|
| But, I was also considering having a 10kW battery to
| store that energy and to have a backup power, like Tesla
| Powerwall - $10k. And then there was work to install,
| permits, my time. Overall my estimate was, realistically
| it'd be ~$25k. Maybe I was wrong.
|
| On my house I have two sections of roof that are
| flat/horizontal. Roof is pretty thin there and although
| there is insulation, on hot days ceiling was getting worm
| in the 2 rooms under these sections. I also was hoping
| that an extra layer of solar would insulate my roof a bit
| more. So I wouldn't have to run AC that much. So the hope
| was to stop wasting annoying $400 on AC in the hottest
| months. But the cost of installing solar felt
| prohibitive. So I've made a quick calculation and spent
| $100 on the reflective roof paint instead...
| danans wrote:
| > The quote for the solar kit that could produce ~1.5kW
| (2170W Solar Kit: 7xURE NSP 310W - Mono 60 Cell - All
| Black Panels + 7xEnphase IQ7 60-Cell Microinverters
| w/QCables + 1x Enphase IQ Combiner 3 + Wireless
| Monitoring) was $6.5k.
|
| Remember to take 23% off for the federal tax credit.
|
| > But, I was also considering having a 10kW battery to
| store that energy and to have a backup power, like Tesla
| Powerwall - $10k.
|
| That's a not-so-small detail, accounting for $18.5k of
| the bid! A battery is also pretty unhelpful for reducing
| the A/C portion of your electric bill, especially since
| most traditional A/Cs require more than the 20A that the
| Enphase 10kWh battery can output and will pretty quickly
| drain any home backup battery that could support that
| current demand.
|
| > So I've made a quick calculation and spent $100 on the
| reflective roof paint instead...
|
| $100 in reflective roof paint, while a great measure to
| take, isn't going to reduce A/C electricity usage more
| than PV, which has the added benefit of offsetting your
| other electricity usage when you are not in the cooling
| season.
| hedora wrote:
| The enphase batteries are stackable to get more amperage.
| However, we were definitely amperage limited when we
| sized ours. We have a few high amp / low duty cycle
| devices.
|
| It can definitely run our 60+ amp HVAC system, but not
| overnight. (We didn't buy it for that, but it's nice that
| we don't even notice our frequent, short outages until
| enphase and pg&e email us...)
| hedora wrote:
| We have an enphase system with a solar array that's a bit
| under 10x that size. We paid about $60k (ignoring tax
| credit) in the bay area, and I think we overpaid.
|
| We have about 2.5 watt hours of battery per watt of solar
| panel, which seems about right around here. (The battery
| is fully charged by the end of day about 95% of the
| time.)
|
| Your quote has 6.6 Wh/W, and the PV bit is small, so
| fixed costs are also biting you.
|
| Edit: we have electric heat, and you probably don't. Our
| worst case days are cold and cloudy, so perhaps the
| battery sizing makes sense, though if you want AC at
| night, you'll want enough solar panels to charge the
| battery and run the AC.
| abc_lisper wrote:
| I didn't get the battery but paid 28.5K (without rebates)
| for a 12.8kW array. I think that's very reasonable.
| Heating, cooling and car charging are covered with around
| 6mWH capacity left a year. Thinking of converting my
| water heater now.
| hedora wrote:
| I like our Ruud/Rheem hybrid heat pump water heater. (The
| two brands are the same company. The only difference is
| whether you pay someone to install it.)
|
| However, it was not trouble free:
|
| The time of day scheduling feature is useless. Once or
| twice a month it gets stuck in "lower temp" mode. The app
| reports kWh used and displays alerts, which is nice.
| Otherwise, there's no reason to give it WiFi access.
|
| Pay for the leak detector option. It's relatively cheap,
| but not included for some reason.
|
| You're likely to have condensation issues unless you use
| a good installer, or do it yourself and follow
| directions.
|
| The power lead on ours wore through due to vibration too,
| so pick someone that's experienced/conscientious enough
| to route wires carefully.
| dd36 wrote:
| It shouldn't cost you more than $2/Watt. Obviously if you
| only do 5 panels, you still have all of the interconnect
| cost and it's not nearly as efficient.
| hedora wrote:
| $2/watt has been way below average for a long time in CA,
| especially with a battery.
|
| I read the national average recently spiked up to $3.10,
| thanks to the Biden administration's mishandling of
| Trump's China Tariffs.
| recuter wrote:
| Sounds wrong, check this out:
| https://www.youtube.com/watch?v=QWJpafOHoD0
|
| 5kWh battery thing for $1,500:
| https://signaturesolar.com/eg4-lifepower4-lithium-
| battery-48...
|
| Growatt 3kW Stackable Off-Grid Inverter for $700:
| https://signaturesolar.com/growatt-48v-3kw-150vdc-
| stackable-...
|
| Solar panels are $2-$3 per watt depending where you live.
| 4x300watt panels is just the ticket, depending where you
| are and whether you can get a 30% tax credit that's about
| $2000.
|
| Whole thing all together would be about $5000. It would
| generate about $1 of electricity a day. Would eventually
| pay for itself over its lifetime if you don't mind
| faffing about with it to get started.
|
| > On my house I have two sections of roof that are
| flat/horizontal. Roof is pretty thin there and although
| there is insulation, on hot days ceiling was getting worm
| in the 2 rooms under these sections. I also was hoping
| that an extra layer of solar would insulate my roof a bit
| more.
|
| It will be slightly cooler underneath it.
| ComputerGuru wrote:
| That's insanely cost prohibitive, tbh. No wonder more
| people aren't jumping at the opportunity. You would need
| 14 years just to pay back the cost of installation, and
| that's assuming zero maintenance simultaneous with
| magically sustained like-new performance.
|
| After those 14 years, you "make" an annual non-compounded
| 7% ROI (again in 2022 dollars).
|
| Spending some of that money on insulation and sticking
| the rest in a savings account somewhere is a much wiser
| bet.
| TedDoesntTalk wrote:
| I've never understood the calculations people make to
| justify that solar roof panels save them money.
|
| Every time I do the calculations, it's money loss.
|
| If you want to install them for environmental reasons,
| great. But don't kid yourself that's is a great
| investment. It's not. Putting the money into an S&P 500
| index fund for 14 years is a better investment. It will
| double about twice in that time.
| maigret wrote:
| If everyone does that, all your stock won't be worse much
| when the world will be either at war or starving. People
| have kinda forgot to think long term clearly. Also, you
| must live in a country where the politics are very anti
| climate. In my country it's a good investment to install
| solar power.
| recuter wrote:
| The batteries are often rated for 20 years, after which
| you're down to 80% capacity, they don't simply stop
| working. Solar panels are rated for 30 years. So yeah,
| pretty hands off.
|
| As for why do it, well, a right sized system allows you
| to be independent from the utility company so if monthly
| financing for it falls to the same ball park you're
| paying for electricity already you've simply locked in a
| rate and hedged against further price hikes.
|
| If I was paying on average $99/mo to PG&E or whomever I'd
| eyeball a $12,000 system financed over 10 years. That
| would get you about 20kWh storage and enough panels to
| keep it full which may or may not be enough for your
| house.
|
| That crossover point obviously varies from house to house
| and what's available to you locally. I think it makes a
| lot of sense for new houses, that way they might avoid a
| potentially very costly hookup to the grid which in some
| locations is tens of thousands of dollars in itself.
| 10u152 wrote:
| 1.5 kW of solar for $25k ? Somethings way off, closer to $1
| per watt.
| wlll wrote:
| This is more reasonable. I have 2x400W solar panels
| sitting in my kitchen right now (they're going on a boat)
| that cost me PS215 each.
| beAbU wrote:
| I think your math is off my an order of magnitude
| somewhere. Your $25k can buy a 40Kw kit according to this1
| South African retailer (excl installation, but my point
| still stands.
|
| Also, don't unferestimate painting a roof. I recently had
| my ~400m^2 roof painted, and the final bill was 50k ZAR
| (~3k USD), and this is in a country with dirt cheap manual
| labour costs. It's a very labour intensive operation if
| done properly.
|
| 1 - https://www.sustainable.co.za/collections/grid-tied-
| solar-po...
| wffurr wrote:
| Installation is most of the cost. So "excl installation"
| isn't a useful number.
| jacquesm wrote:
| I always wondered why in such climates we don't simply stick
| mirrors on the roof (cheap) but solar panels would seem to be
| the best option in the longer term (much more expensive than
| either mirrors or white paint). But you are absolutely right:
| black or dark gray roofs are quite silly in a hot climate.
| maigret wrote:
| I have the same question, it would seem a quick win to have
| optimized house colors for the current temperatures. Many hot
| countries do it right, but especially northern architecture
| hasn't adapted as well. Also, too much unshadowed windows.
| There's a lot to win with well thought architecture.
| seltzered_ wrote:
| Changing how roofs are approached (color, materials) may also
| have a (possibly beneficial) hydrological effect, even better
| would be some form of vegetation grown on roofs (likely called
| 'green roofs' to some) to help with evapotranspiration for
| facilitating a small water cycle (helping water vapor travel
| inland) and reduce the 'urban heat dome' effect.
|
| (see Millan Millan's papers like
| https://academic.oup.com/bioscience/article/69/2/143/5254231 ,
| can link to some other newer stuff if desired)
| WhompingWindows wrote:
| In northern New England, we see a lot of homes using heating
| oil and woodstoves. These create a lot of local emissions and
| can be expensive or use a lot of time/effort (woodstoves). Heat
| pumps that work especially well in cold climates would be a
| huge efficiency gain over oil, woodstoves, and electric
| resistive space heaters which are also commonly used as stop-
| gaps in the region.
| gumby wrote:
| > To give an example, houses in the Bay Area has gray/black
| roofs.
|
| Those are no longer legal. Title 24 requires a "cool roof" *
|
| When I had my roof re-covered a couple of years ago the roofer
| apologized and said he had to use a light color. Which wasn't a
| problem for me so no apology was needed.
|
| * https://coolcalifornia.arb.ca.gov/cool-roofs-codes-and-
| stand...
| zbrozek wrote:
| My understanding is that you can insulate your way to Title
| 24 compliance. You just have to have a total ingress
| performance over some level.
|
| Now that said, it would still be better for our communities
| to reflect this energy back out into space to reduce
| environmental heating. Houses in my area at solar noon have
| almost half a megawatt of heating potential. By municipal
| code they are not allowed a roof reflectivity of more than
| 40%.
| gumby wrote:
| I guess having mirrors on all the houses could cause
| problems for other people, even for flat roofs. But I
| agree: reflecting the incident beams is important: when it
| emerges as heat (IR) it can be trapped by GHGs.
|
| I had been thinking of the reflectivity benefit rather than
| the reduction in air comditioning.
| hedora wrote:
| That's strange. We just built a house in the Bay Area with a
| black roof, and have never heard of this. It passed
| planning/inspection, and the thing you linked says we are in
| a title 24 zone.
|
| We hadn't thought about it, and would likely have opted for a
| lighter roof, had someone pointed it out to us.
| oefnak wrote:
| Well, I assume you covered it with solar panels, so it
| doesn't really matter.
| fnordpiglet wrote:
| sundvor wrote:
| Seems like a better idea to cover the roofs with PV panels, to
| be honest. This would reflect heat _and_ provide power for the
| cooling / travel / regular house electricity.
| stephen_g wrote:
| Why not both? If you have a light colour roof, you can use
| bifacial panels and get additional generation for the same
| surface area!
| joshocar wrote:
| This is one of the reasons metal roofs a nice, they reflect
| heat and you don't need to paint them white, they make special
| paints for metal roofs that help reflect the heat and also look
| nice.
| baybal2 wrote:
| an9n wrote:
| Couldn't agree more.
|
| I'm in the UK and in the process of installing underfloor
| insulation in a house built around 1890. It is a flooboards-up
| job involving a windproof one way moisture permeable membrane
| above the joists, with hygroscopic insulation on top, and then
| a vapour control barrier on top of that, with all edges of
| layers taped to the joists where possible, all holes for wires,
| pipes etc. sealed with tape, and finally membranes brought up
| to wall behind the skirting boards. It's going to cost around
| PS1k for a room of about 25m2. We have double glazing, the
| walls aren't particularly cold in winter, and the roof is
| insulated. I'm convinced most of our cold is coming through the
| floor and I reckon this job (along with the rest of the house
| in time, ugh) will make a huge difference.
|
| But I'm having to do it myself because there are literally no
| specialist fitters where I live, and there are no government
| incentives that I am aware of. Why aren't the government going
| hell-for-leather for insulation etc.?
| MobileVet wrote:
| Black / dark tile roofs across the south are completely
| ridiculous. I doubt people understood this when shingles were
| first developed but we do now and we should adjust accordingly
| Hellbanevil wrote:
| The main reason they are dark is because they are made with
| oil.
|
| Asphalt tiles are fairly cheap, and that's a good thing. It's
| the labor that makes up most of the cost of a roof.
|
| I'm trying to get up the nerve to shingle my four bedroom
| home, and it's not the cost of materials I'm worried about.
| It's my body.
|
| My fear with global warming measures is the poor, and middle
| class, will be required to bear the brunt of the preventative
| measures.
|
| I guess the race is on to develop a 50 year life expectancy,
| but reasonably priced, white shingle? They might be out
| there? I really haven't researched them.
|
| If anyone knows a cheap roofing contractor in the Bay Area,
| please divulge?
|
| Twenty years ago I had a estimate of $25,000. I think that's
| too much now. I'm a ex General Contractor.
| Wowfunhappy wrote:
| > My fear with global warming measures is the poor, and
| middle class, will be required to bear the brunt of the
| preventative measures.
|
| They'll also bear the brunt of the effects of global
| warming, and those will be worse.
|
| We should try to make environmental programs as equitable
| as possible. But first and foremost we need to _do them!_
| Hellbanevil wrote:
| Yea, but trying to squeeze more out of the lower middle
| class, and poor, dosen't seem kind at this point in
| history.
|
| I see a lot of virtue signaling out there.
|
| Most of us can't afford a electric vechicle, and those
| federal credits seemed to just go to people whom could
| afford any vechicle.
|
| I can't even afford the smog check, and registration, on
| my 4 banger toyota. A Truck I've keep going 20 years. It
| uses very little gas. (My vechicle has always been tuned
| up properly. I thought by now we would have had free smog
| checks for the poor? In CA we have a low income deal that
| was enacted when CA decided to require smog checks. It's
| so complicated most people don't use the "gift". You need
| to bring your car to a mechanic in order to get any money
| back. Shade Tree mechanics are out of luck.
|
| My point is the corporations/government will pass any
| Global Warning measures down to us.
|
| We are already tapped out.
|
| If we are really serious about Global Warming lets go
| after the wealthy boys first. Take away their private
| jets.
|
| And enough with their Globalization. If they can make a
| product that dosen't need to be shipped long distances,
| have them make it here.
|
| I'm a Democrat, and winced when Biden pretty much gave a
| FY to the oil companies in order to sound Progressive. I
| knew at the time, the poor can't afford to pay more for
| gas, and natural gas.
|
| Now--I don't blame the president for this spike in gas
| prices, but I would have rather have him say this is a
| big problem, and we can't just do away with oil.
|
| Be it my PG&E bill that just seems to go up, and the
| $6.69 gas at my Chevron station, the poor are already
| paying to much of their income on a complex problem. (My
| gas station raised their prices the minute they started
| talking about inflation, and the Russia sanctions. It is
| pure greed. They made a record profits in the past few
| years.
|
| Sorry about my rant. I just don't like being squeezed so
| much, while my wealthy neighbors buy crap from Amazon,
| and think they are doing their part by driving a Tesla.
| UncleEntity wrote:
| When I left California I was driving a '67 ford galaxy
| which, being over 25 years old at the time, wasn't
| required to be smogged anymore and was fully surprised
| when they made me do it when I registered it in Arizona
| (where it is anything post-66 has to have smog). Even my
| motorcycle had to be smogged (which, I believe,
| California doesn't require) and that thing couldn't help
| but get really good gas mileage.
|
| So, fear not, a couple more years and you will be smog
| exempt.
| hadlock wrote:
| My daily driver is a 1955 and I'm exempt from safety
| inspections at this point. I also have a one-time(!) $175
| registration fee in my state. If you can keep up with the
| basic maintenance (grease certain joints every couple
| thousand miles, etc)the lack of regulatory oversight on
| these older vehicles can sometimes push them back into
| being more affordable than driving a 10-15 year old car.
| Just don't get in a wreck in them, crumple zones weren't
| really invented until the 90s.
| Hellbanevil wrote:
| No--in CA it's 1975, or earlier. It's a rediculious law
| because the old cars do not put that many miles on the
| road. I wish it was 30 years.
|
| While I'm on my soap box; Neusome (a guy I went to high
| school with (Redwood, and voted most Fashionable, a
| liberal Marin county boy) has a bill on his desk that
| would do away with fees associated with Parking Tickets.
| As of today, he has not signed off on it. The only reason
| I can think of is he's getting more middle of the road
| for a run at the big office?
|
| These extra fees and fines are not fair to the poor. A
| parking ticket in SF is running $80 bucks without fines.
| $5-6 an hour if you find the right spot. Neusome knows
| this personally.
|
| He barely graduated from Redwood High School, and dropped
| out of college due to some nebulous learning disability.
| He opened some coke dens in SF, and a few Bootjack liquor
| stores with family money. The SF bars went up in flames
| because they were poorly managed. Oh yea, his cousin
| Brendan has a DUI that disappeared? I might write a book
| on this guy one day. While I seem pissed, he's better
| than the alternatives.
|
| If he wasn't born wealthy, he would be in the Embarcadero
| in SF with a needle stuck in his arm.
| rswail wrote:
| You need to vote for people who have policies to increase
| tax on the rich.
|
| Government will pass climate change measures on to those
| that squeal the quietest.
|
| Globalization is not the cause of climate change, it's a
| natural effect of economics as our technology and
| capabilities improve.
|
| No one is saying to do away with oil, but that also means
| that oil companies don't have a social license to extract
| excessive profit. So tax them.
| jacquesm wrote:
| You can easily do it yourself, I did it first on a chicken
| coop to practice and once I got the hang of it I did a 145
| square meter roof on top of a two story building in
| relatively short time. The clock was ticking because we
| were about to have frost and that makes working on the
| North side of such a roof next to impossible. If you have
| to remove the old stuff first use a flat shovel, that works
| the fastest compared to more fancy tooling.
|
| Make sure you invest in a proper safety harness, they're
| not that expensive and even if I really hope you won't need
| it you'll be very happy you did that in case you do...
| hedora wrote:
| We recently paid thirty for asphalt, simple design, under
| US average size.
|
| I once knew a handyman that swore by painting over black
| membrane roofs with some sort of white rubber patch paint.
| It was probably a terrible idea, but I wonder if such a
| product exists for asphalt roofs.
| SoftTalker wrote:
| I think people understood. It's just that tar/asphalt is
| cheap and makes a very good roofing material.
| hsbauauvhabzb wrote:
| Pretty sure they were recently banned in Sydney, Australia.
| josh64 wrote:
| Not quite unfortunately - the new Planning Minister caved
| to the property developer lobby:
| https://www.theguardian.com/australia-
| news/2022/apr/09/plan-...
| jdironman wrote:
| What exactly are the challenges with producing lighter
| colored roofing?
| freen wrote:
| People who are happy to let the world burn so they can
| have their roof look the way British roofs look.
| ip26 wrote:
| Asphalt is black, and a high albedo is hard for anything
| to maintain with dirt, dust, and age.
| stephen_g wrote:
| That's not it in Australia - we don't use asphalt
| roofing. Normal roofs are tile, steel or (more rarely)
| zinc here.
|
| I think the US is fairly unique in that regard. I'm so
| used to our houses here that the idea of using shingles
| made of asphalt just seems bizarre to me.
| Tagbert wrote:
| I had assumed that the white color would come from a
| white granular material impressed into the asphalt base
| mrfusion wrote:
| But that 10kw isn't going directly into your house. The attic
| is designed to vent the air and let that hot air escape.
| cy_hauser wrote:
| For my house the problem is that the sun's energy is
| converted to radient heat which makes its way hours after the
| air has cooled. The HVAC people have said no amount of
| insulation or attic fans will help. They suggest radiant
| barrier roofing of varoius types. The simplest being
| reflective paint, which the HOA won't allow.
| wolverine876 wrote:
| Agreed, though you still need to account for cold days when you
| want more heat in the house.
| amluto wrote:
| If the roof assembly is decently insulated, then relatively
| little of that 10kW heats the house. So, while improvement is
| available, it's not nearly that large.
| hn_throwaway_99 wrote:
| Still, though, I have to wonder what the equivalent "CO2
| reduction" would be considering that a white roof is likely
| to radiate most of the incoming sunlight back into space,
| where if it is radiating in infrared then that heat is more
| likely to be trapped on Earth.
| amluto wrote:
| Indeed.
|
| https://en.m.wikipedia.org/wiki/Urban_heat_island
|
| https://en.m.wikipedia.org/wiki/Reflective_surfaces_(climat
| e...
| throwaway3334 wrote:
| For now, everyone is free to pump out kilowatts of heat
| with their roofs, parking lots, air conditioners into the
| surrounding air. It is not considered pollution, even when
| it is already 100 degF outside.
|
| On the days when there is an inversion in the atmosphere,
| the hot air stays trapped. People have to run ACs in their
| houses, stores and offices. And that results in even more
| heat routed to the place, with ACs units, literally pumping
| energy from the solar arrays somewhere in the desert into
| the city.
| rocqua wrote:
| My intuition says that the volume of inside vs outside
| air is so big that it has little effect.
| throwaway3334 wrote:
| You can look at how much space roofs cover in the suburb
| in the Bay Area. It'd be roughly 25% streets, 40% roofs,
| 30% backyard, 5% front-yard. Adding white reflective
| coating increases "Solar Reflectance" and decreases
| "Thermal Emittance" and absorption. Most dark roof
| materials reflect 5 to 20% of incoming sunlight, while
| light-colored roof materials typically reflect 55 to 90%.
| A white roof coating that you can purchase at your
| regular home improvement store would do that 90%.
|
| So effectively, in the suburban area there is an
| opportunity to change our average solar reflectance by
| ~32% [(90% - 10%) * 40%]. If we just abandon the idea
| that a good house should look like a house in Normandy
| and have a black roof.
|
| [edit: I've opened a section of sat map (in Sunnyvale,
| near Reed Ave/Sequoia Dr.) and estimated
| roof/street/backyard/front-yard by area, for a lot of 2
| houses and adjacent street. The numbers above are from
| that estimate. Heat and noise of ACs is somewhat local
| (urban heat island effect, etc), so that local estimate
| is what counts. It is not surprising that we can have 40%
| roofs. Land is expensive in the suburb like that.]
|
| As per: https://en.m.wikipedia.org/wiki/Reflective_surfac
| es_(climate... - "If all urban, flat roofs in warm
| climates were whitened, the resulting 10% increase in
| global reflectivity would offset the warming effect of 24
| gigatonnes of greenhouse gas emissions, or equivalent to
| taking 300 million cars off the road for 20 years. So it
| seems, there is not only local/urban heat island effect,
| but even some global effect. To put this into
| perspective, Tesla sold 2 million vehicles. No idea, if
| the Wiki numbers are correct...
| uxp100 wrote:
| I suspect that there are good stats somewhere, but I
| think that 40% roofs might be a pretty high over estimate
| in say, Sunnyvale, or even San Jose.
| rch wrote:
| I'm not aware of any stats, but I've experienced the
| difference between hot neighborhoods and cooler
| neighborhoods, right next to each other in Houston. It
| would be great to have a quantitative measure for this
| effect, similar to a walk score (which isn't perfect, but
| can be occasionally useful).
| kolinko wrote:
| Are you sure it's because of AC and not the amount of
| concrete pathways compared to green areas, vegetation and
| shade from trees? Also various thermal properties of the
| ground?
|
| Even if houses were 50% of the land area, they take up a
| miniscule amount of air volume. Also, hot air floats up,
| so there is little chance you could feel the heat from an
| AC outside. On the other hand, if the earth is hot
| because you have few trees, you will feel it everywhere
| when walking on a sidewalk.
|
| In Europe at least it's common knowledge that you need to
| have trees and greenery everywhere to make heat bearable
| outside. If you replace trees and grass with concrete you
| get an island of heat that will be unbearable during
| summer to walk through.
|
| edit: thermal camera image of a walkway with trees in
| summer https://images.app.goo.gl/m2XN7rqodavDcwoE9
| 8bitsrule wrote:
| At this time last year, this region was subjected to a
| 'heat dome'. Luckily this building has a 'cool dome' in
| the basement. Spent a few days listening, reading and
| solving down there (12-16degC cooler).
|
| Much cooler temperatures (13degC) are found just a few
| feet below ground. (Memorable to those who've visited
| 'root cellars.) Before long those mysterious 'underground
| cities' in Anatolia may not seem so mysterious. It's a
| low-cost, low-tech, zero-energy solution, used by native
| communities in many regions of the world.
| wcoenen wrote:
| > _Much cooler temperatures (13degC) are found just a few
| feet below ground. (Memorable to those who 've visited
| 'root cellars.) Before long those mysterious 'underground
| cities' in Anatolia may not seem so mysterious._
|
| When the London metro was built (over a century ago), the
| clay was at 14 degrees C. But over time, it heated up
| from all the power dissipated by the metro system. Now it
| is around 20 to 25 degrees C and doesn't really act as a
| heat sink anymore. The same happened in the NY subway.
|
| So soil can act as a great heat sink for a while, but not
| forever. I suspect the same would happen if you'd put a
| modern city underground and relied on the temperature of
| the soil instead of pumping heat out somehow.
| smaudet wrote:
| This and geo-thermal. The crazy megalomaniacs pushing
| solar are as bad as the rest of oil/coal kingpins,
| unsustainable and another ecological train-wreck in
| progress.
| AngryData wrote:
| Yes this. It helps but it isn't a magic bullet because the
| roof is already airgapped from the roof and the house
| insulated from the attic. If the roof was directly insulated
| shingles would curl up and start failing within one or two
| summers due to the heat. That is why there are roof vents,
| gable vents, and soffit vents, to let air freely flow into
| and out of the attic/roof cavity.
| DubiousPusher wrote:
| > If the roof was directly insulated shingles would curl up
| and start failing within one or two summers due to the
| heat.
|
| This is an old school carpentry trope and yet I've never
| actually seen any statistical evidence indicating that
| roofs over vaulted ceilings which are directly insulated
| must be replaced more often than non-vaulted.
| cpwright wrote:
| Anecdotally we have about 1/3 of our roof with a vaulted
| ceiling and the other 2/3 with an attic. The side with an
| attic is the side that would be suitable for solar panels
| (more sun at the right angle) or adjacent to the vaulted
| ceilings. The leaks that came up were all on the
| insulated vaulted ceiling side; starting about 25 years
| old, and we had another every couple years for about five
| years until replacing the roof. The attic parts never had
| any problems.
| SoftTalker wrote:
| We have a vaulted ceiling and there is still an air gap
| under the roof. The ceiling "vault" is separately framed;
| there is still a foot or two of air space between the top
| of the vault and the roof deck.
| amluto wrote:
| As far as I know, it's important to have outdoor air that
| flows under the roof in _cold_ climates to avoid ice dams.
| Otherwise insulating the roof deck is just fine and
| possibly even advantageous.
|
| An unconditioned attic is not so great because it's
| difficult or impossible to do a good job of avoiding
| leakage into the living space. Also, any mechanical
| equipment in the attic would like to be in conditioned
| space.
| csomar wrote:
| Yeah this was figured out in the Mediterranean probably a few
| hundred years ago: https://www.santorini-view.com/white-houses-
| of-santorini
|
| Unfortunately, we are losing some of this cumulative knowledge
| due to it not being documented, and due to the looks of
| alternatives (although the grey buildings in the US are as ugly
| as it can get)
| drjasonharrison wrote:
| Well also asphalt tiles being cheaper material and cheaper
| installation on sloped roofs (snow!) over wood frame
| construction.
| jacquesm wrote:
| They're only cheaper in the short term. Long term energy
| costs and replacement costs factor in strongly, and chances
| are that once you make that calculation you'll end up with
| old fashioned terracotta roofs being cheaper over the life
| of the house.
| JasonFruit wrote:
| We're not losing the information that light colors heat less
| in the sun. Neither could anyone who spent five minutes on a
| black roof in the sun forget that tidbit. It's just that
| other factors than the energy required to cool a building
| took precedence in the past.
| kjkjadksj wrote:
| Anecdotally it seems like we are. The rad thing to do in my
| area of california is to paint your white washed spanish
| style home mud brown or ozzy osbourne black. Then you have
| to install a much more powerful AC system when in the past
| maybe just opening windows and getting crossbreeze was
| enough. All these houses used to have awnings over sun
| facing windows when they were build in the 1920s but at
| some point that must have been seen as ugly and its now
| pretty rare to see.
| dotancohen wrote:
| > The rad thing to do in my area of california is to
| paint your white washed spanish style home mud brown or
| ozzy osbourne black.
|
| It seems that the Ames Research Center is rather rad
| hardened, then. Fitting. JPL too, for that matter.
| kube-system wrote:
| That rad thing to do is an example of what they meant by
| other things taking precedence.
| foobiekr wrote:
| Hell most of the 1950s and 1960s Bay Area housing stock is
| worse - it's tar and gravel roofs without any significant
| insulation thereby turning houses into ovens. The right answer
| to most of them is a new foam roof which both provides
| insulation and reflectivity being white but people get quite
| upset about the foam roof thing, especially with Eichlers.
| epmatsw wrote:
| There's actually a $500 tax credit to install reflective
| shingles for this very reason.
| https://www.energystar.gov/about/federal_tax_credits/roofs_m...
| boardwaalk wrote:
| > The prototype delivers 100% heating at 5degF at double the
| efficiency, and 70% to 80% heating at -5degF and -10degF
|
| So, 2 EER (2x of resistive heat) at 5F, 1.8 at -5F and 1.6 at
| -10F? Is that right? Seems awkwardly worded.
| brtkdotse wrote:
| That's uh, pretty terrible? My 15+ year old Nibe gets as much
| hedora wrote:
| It says "double" the efficiency, so I assume they mean 2x the
| COP of the previous model at 5F, and 1.7-1.8x the old COP at -5
| and -10F.
|
| A COP of 2 @ 5F isn't a "breakthrough" vs. the first
| commercially available model I could find numbers for, and a
| COP of 1.5 at -10F seems implausible:
|
| https://www.nordicghp.com/2017/01/heat-pump-effective-temper...
|
| Honestly though, this press release is so poorly written, I
| wouldn't trust the numbers match up to anything.
| mlyle wrote:
| > So, 2 EER (2x of resistive heat) at 5F
|
| Yes (or double of previous model as another commentator points
| out-- hard to say).
|
| > 1.8 at -5F and 1.6 at -10F?
|
| They've not told us the efficiency-- just that it provides
| 70-80% of nameplate amount of heating at those temperatures.
| boardwaalk wrote:
| Ah, I see. I figured they'd keep the input energy constant
| because otherwise you're not saying much at all (you could
| figure that the efficiency plummets and you'd be better off
| with a space heater).
| mlyle wrote:
| It's possible. Also possible it's barely outperforming the
| space heater at the lower temperature and input power has
| increased. They've not told us enough.
| coryrc wrote:
| The energy input goes down because it physically can't run
| a differential high enough to get full heating output.
|
| They could choose the lowest temperature, find it's power
| input, then fix it at that amount. But at low temperatures
| the concern is usually less "efficiency" and more "am I
| going to freeze to death", because in most of the cold
| areas temperatures aren't usually that cold for that long
| (though in others it definitely is, and if you're running
| at 1.6 COP for a significant amount of time, you're better
| off with more insulation than a heat pump).
| ocdtrekkie wrote:
| With natural gas hitting four times it's cost last year, couldn't
| come at a better time. Next winter, heat will cost more than rent
| in Chicago.
| SV_BubbleTime wrote:
| Don't worry, the rent will go up too.
| formvoltron wrote:
| Anyone know how this compares to a geothermal system?
| thinkcontext wrote:
| Heat pumps for geothermal applications don't need to be
| optimized for less than 0C.
| danans wrote:
| It doesn't really compare since ground-source/geothermal
| systems are designed to work with a smaller temperature
| difference (since the earth stays about 50F most of the year a
| few feet down).
|
| Business wise, if this really works at 2COP at 5F, this might
| take over most of the market served by ground source heat pumps
| though.
| overeater wrote:
| Does anyone know why there has never been any breakthroughs in
| air conditioning for 50 years? Windows air conditioners have been
| incredibly heavy, loud, expensive, and resource-intensive for so
| long. Even a small room needs one that is back-breaking to
| install. And pretty much everyone in the world (except those with
| central air) needs a couple of air conditioners now.
|
| Sure the "efficiency" is improving but it's mainly tricks for
| turning it on/off at better times. I know there are some U-shaped
| ones now, but it's just a slightly different styling.
|
| Edit: two commenters pointed out examples of air conditioners
| which are 77 lbs and 56 lbs. As a comparison, the OSHA
| recommended lifting weight is 50 lbs. I would love to see someone
| apply Apple's obsession with thinner, lighter, "revolutionary new
| design" to ACs.
| HPsquared wrote:
| Most poetically answered by Flanders and Swann:
|
| The First Law of Thermodymamics.
|
| Heat is work and work is heat
|
| The Second Law of Thermodymamics:
|
| Heat cannot of itself pass from one body to a hotter body
|
| Heat won't pass from a cooler to a hotter
|
| You can try it if you like but you far better not-a
|
| 'Cos the cold in the cooler will get hotter as a rule-a
|
| 'Cos the hotter body's heat will pass to the cooler
|
| Heat is work and work is heat and work is heat and heat is work
|
| Heat will pass by conduction and
|
| Heat will pass by convection and
|
| Heat will pass by radiation
|
| And that's a physical law
| kristiandupont wrote:
| I have pondered this as well and studied it a bit. I feel that
| there is room for new tech that can help with this increasingly
| dire problem.
|
| Thermoacoustic refrigeration seems to be one of the more
| promising technologies but I would love to hear about others.
| vincnetas wrote:
| Thermoacoustic... love to hear about others :) yes pun
| intended.
| rocqua wrote:
| As I mentioned elsewhere:
| https://news.ycombinator.com/item?id=31791936 there is a
| company that claims to use thermoacoustics for general heat-
| pump duty. I believe they are targeting European style
| hydronic heating. Aiming to be efficient whilst still
| producing the 80c water that many older hydronic systems here
| in Europe still require.
|
| Interestingly, they aren't that loud because any sound lost
| is energy lost, so they try very hard to 'keep it quiet'.
| lock-the-spock wrote:
| > And pretty much everyone in the world (except those with
| central air) needs a couple of air conditioners now.
|
| Absolutely not. Where I live we had 34degCtoday but I would
| still never buy an A/C unit, which will ruin your health
| (heat/cold shock, bad air moisture levels, ...), waste immense
| amounts of energy and makes leaving the house a pain as the
| rest of the world becomes uncomfortable. Most of my friends
| here earn very well but I can't think of anyone that would see
| a reason to buy one. Live with the temperature and adjust -
| like the famous Iberian or Mexican siesta, where you simply
| accept that midday are low energy hours.
|
| But even beyond this, the reason for A/C use is just bad
| architecture and city design. More trees in the streets can
| lower the temperature in the street itself and nearby
| residences easily by 1-2 degree. Less absorbing surfaces
| (asphalt, stone sidewalks, ...) make another difference.
|
| And as regards the houses, there are plenty of ways for passive
| and energy efficient buildings that keep cool. In the middle
| east they have built self-cooling houses for centuries.
|
| And in all this, even if you are stuck with bad streets and
| architecture, you can simply adapt, use efficient ways to keep
| cool (a fan can work wonders) and drink warm rather than iced
| drinks and your circulatory system will thank you as you don't
| switch regularly get shocked with 10-15deg differences and you
| will sweat much less.
| hahamrfunnyguy wrote:
| I'd been using a window unit for the bedroom but got sick of
| taking it in an out and decided to see how long I could
| manage without it. Now I prefer no air conditioning because
| of the reasons you state above - it feels much more
| comfortable being outside on hot days. I keep the windows and
| doors closed during the heat of the day then open them up
| when it's cooler outside than it is inside.
| bonzini wrote:
| Let me guess, where you leave there are "serious" blinds
| outside the windows that help keeping sunshine out. I wonder
| when Central Europe will start installing them.
| adrianN wrote:
| I also won't buy AC for myself anytime soon, but I'm still
| young and healthy. Older people have a lot more serious
| problems with heat waves.
| sparsely wrote:
| Mini splits are widely used and have become dramatically more
| economical and popular over the last decade or so. They are
| much quieter and more efficient than window units.
|
| Some areas ( _cough_ nyc _cough_ ) may need some regulatory
| breakthroughs but the technology is there.
| foobiekr wrote:
| Can you expand on the regulatory issues or provide a pointer?
| stormbrew wrote:
| Window units really only exist at all because of buildings that
| can't accommodate better designs for either practical or legal
| reasons. There's just no amount of innovation that can make it
| so that having the intake and the outtake right next to each
| other without a nearly perfectly sealed box on one side (ie. a
| fridge or a freezer) is gonna be anything but a big ugly noisy
| energy gobbler.
|
| If you can't have central, you should have mini-split, and
| that's where all your problems get solved. If you can't get
| mini-split because your landlord won't let you drill conduit to
| outside then you're just kinda stuck and the laws of
| thermodynamics are your enemy, not a lack of innovation.
| iancmceachern wrote:
| "Lisa, in this house we obey the laws of thermodynamics!"
|
| It's physics and thermodynamics. It's basically the same as
| with any heat engine, internal combustion engines included.
|
| There is a certain maximum theoretical efficiency that is not
| 100%. When we build real machines (not theoretical ones) there
| are real world losses like heat loss, fluid flow friction,
| moving part friction, electrical inefficiencies, etc. Those
| real world losses van be gradually worked on over time,
| improved incrementally to yield small gains in efficiency. But
| never large ones, and never more than the theoretical max
| efficiency, which is not 100%.
|
| It's like hybrid cars (not plug in hybrids, but just gas
| powered hybrids), they've doubled or trippled the mileage
| compared to a comparable regular car, but they will always need
| gas, they will never be 100% efficient.
|
| Same with this. There will always be some fundamental
| electrical losses in the copper in the motor, air gap losses in
| the motor, friction in the bearings and fluid, heat losses to
| the environment, etc. It's the cost of doing the work. There is
| no free lunch, so we can only incrementally improve the little
| losses over time.
| eloff wrote:
| My understanding is that heat pumps can be over 100%
| efficient because they're actually moving heat from A to B
| where one side is the outside environment. It doesn't violate
| thermodynamics if you view the Earth as a closed system. The
| heat pump itself is not a closed system.
| iancmceachern wrote:
| Thanks for highlighting this because it's a common
| misconception.
|
| "The coefficient of performance or COP (sometimes CP or
| CoP) of a heat pump, refrigerator or air conditioning
| system is a ratio of useful heating or cooling provided to
| work (energy) required.[1][2] Higher COPs equate to higher
| efficiency, lower energy (power) consumption and thus lower
| operating costs. The COP usually exceeds 1, especially in
| heat pumps, because, instead of just converting work to
| heat (which, if 100% efficient, would be a COP of 1), it
| pumps additional heat from a heat source to where the heat
| is required. Most air conditioners have a COP of 2.3 to
| 3.5. Less work is required to move heat than for conversion
| into heat, and because of this, heat pumps, air
| conditioners and refrigeration systems can have a
| coefficient of performance greater than one. However, this
| does not mean that they are more than 100% efficient, in
| other words, no heat engine can have a thermal efficiency
| of 100% or greater. For complete systems, COP calculations
| should include energy consumption of all power consuming
| auxiliaries. The COP is highly dependent on operating
| conditions, especially absolute temperature and relative
| temperature between sink and system, and is often graphed
| or averaged against expected conditions."
|
| https://en.m.wikipedia.org/wiki/Coefficient_of_performance#
| :....
|
| More detail here:
|
| https://physics.stackexchange.com/questions/489467/can-a-
| hea...
|
| In short, a heat pump is more efficient when compared to
| using the energy to directly generate heat because it's
| more efficient to move heat than generate it.
| Dylan16807 wrote:
| They're not talking about that 100.
| mensetmanusman wrote:
| That means you need somewhere to move the heat to, and the
| thermoynamics of heat capacity are not forgiving if you are
| trying to make something lightweight. You need atoms and
| lots of entropic states to store heat :)
| bushbaba wrote:
| Idk this "toshiba" AC has a built in heat pump and operates at
| super quiet levels. Would I call it a "breakthrough", likely
| not. But it is a meaningful improvement over an AC released
| decades ago.
|
| https://www.homedepot.com/p/Toshiba-14-000-BTU-12-000-BTU-DO...
| JaimeThompson wrote:
| Check out the inverter type ones such as this one [1] It isn't
| light but it is quiet and adjusts the amount of power it uses
| depending on cooling needs much better than a typical window
| unit making it more efficient.
|
| [1] https://www.midea.com/us/air-conditioners/window-air-
| conditi...
| daydream wrote:
| The Midea U window AC units are a really good product. I am
| easily cooling a roughy 1,200 square feet space with only one
| of the 12k BTU units and a few ceiling fans, and it typically
| gets into the 90's F here in the summer with significant
| humidity.
|
| No affiliation to Midea just a satisfied customer.
| uxp100 wrote:
| I agree. The U shape is a gimmick, but a good one. It helps
| it be quieter inside, but even outside they are quite
| quiet. I have whole house AC, but I like the windows open,
| I like being hot. Just not when I'm sleeping. Basically
| only downside is a truly terrible app that is the only way
| to access just a few features.
| JaimeThompson wrote:
| Terrible doesn't begin to describe that app. Honestly
| what does the turbo button in the app even do?
|
| I have one in a room on the far end of the house that the
| main AC can't reach, it helps reduce power usage since I
| can keep the rest of the house warmer.
| devwastaken wrote:
| Patents, intellectual property, etc. It's why every appliance
| is trash nowadays. Big corps are IP holders, and there's only
| so many ways to engineer certain actions. Regardless even if
| you try to startup a company you'll be pushed out by the
| control big corps have over manufacturing.
|
| We need to start nullifying IP if we ever hope to see
| innovation.
| mensetmanusman wrote:
| Probably not this, most IP can be worked around, and
| especially in the area of AC operations and thermodynamics,
| that hasn't changed in almost a century.
| jeffbee wrote:
| Talk about moving the goalposts. You asked, people answered.
| The revolution is that you can now buy an 8000 BTU unit that
| weighs little, costs almost nothing, and can be installed
| anywhere in a few minutes.
| [deleted]
| Ekaros wrote:
| Thermodynamics are harsh mistress... Add that to limitations on
| what can be used as refrigerants. The reality that these
| systems need to operate with rather long duty cycles for
| decade+ at minimum. And the reality is that there isn't much
| magic in how they operate. Compression and expansion of gas.
|
| Computers are actually a very special case. They don't really
| do any physical work in sense other stuff does, thus
| miniaturization gives lot of gains there. I have long said that
| small drones are answer to flying cars. We have them and they
| are small, but lifting people is hard work.
| vanderZwan wrote:
| AFAIK the physics of heat pumps is considered to have been
| fully figured out for ages and all that's left is the
| engineering. Maybe it wasn't considered a "sexy" enough topic
| to nerd out over and hyper-optimize?
|
| Edit: it might also be an issue of diminishing returns of
| better efficiency compared to how difficult it is to produce
| and maintain a better unit. Thermodynamics can be a pain like
| that.
| mikepurvis wrote:
| We got a U-shaped one for a big open attic space and I'm a fan
| of it. It cost more and was a little bit more drama to install
| (came with a big support bracket thing), but it's very
| effective and quiet. We meant it as a stepping stone to
| eventually putting a mini-split setup on that side of the
| house, but it might end up just being the long-term solution.
|
| EDIT: Oh lol, the unit we got was actually one of those Midea
| ones linked in a sibling comment.
| pengaru wrote:
| What a misleading clickbait headline.
|
| This isn't a technology breakthrough, this is a DOE
| policy/partnership/funding "breakthrough".
| bitexploder wrote:
| Right? We have Fujitsu units that maintain their COP down to 0F
| and still are 80% efficient below there down to like -15
| fithisux wrote:
| I'll believe it when I see it marketed. Even if it works I doubt
| it will be within financial reach for most people.
| asdfman123 wrote:
| "Tapping into the emerging clean energy market is a huge economic
| opportunity that will bring a bolstered manufacturing sector,
| good paying jobs, and a brighter, cleaner future to _Texas_ and
| communities across America."
|
| If anyone else is confused by this, it's because Lennox is
| headquartered in Texas.
| davidro80 wrote:
| You are confused by this? It's a straightforward statement.
| InsomniacL wrote:
| what's not straight forward is understanding why the
| statement lists a single state and everyone else falls under
| 'communities across America' which the comment above clears
| up.
| davidro80 wrote:
| mrfusion wrote:
| What's the breakthrough on the tech old level? What did they
| discover?
| tootie wrote:
| It can operate efficiently at lower temps. Current air source
| heat pumps see degraded performance and below freezing temps
| and will not be able to effectively heat a home at the lowest
| temps that can occur in the northern hemisphere.
| mrfusion wrote:
| Thanks. But I'm trying to figure out how they do that.
| margalabargala wrote:
| The "secret sauce" of the increased efficiency is that
| they're using thermoacoustics, which previously had been a
| technology used in one-off applications with a large budget
| (e.g. the James Webb telescope uses it to stay cool). Prior
| to now there were no manufacturers providing the technology
| to be widely available at scale.
| PaulDavisThe1st wrote:
| No idea how the Lennox units in TFA do it, but the Mitsubishi
| "hyper-heat" units do it by diverting a small amount of their
| output back into heating up the refrigerant at very cold
| temperatures. It starts to get a bit "slushy" at the low end of
| the performance range, which impacts the ability to move heat.
| By warming it back up to the bottom of its ideal operating
| range, the whole system functions more efficiently.
| londons_explore wrote:
| Lab vs typical observed performance differs quite widely for many
| home heating systems.
|
| Thats because typically each appliance is tested at optimal
| conditions (eg. water flow rates). Then, in a real deployment,
| every parameter differs a little from optimal (eg. the water may
| circulate slower than expected because you have longer pipes
| around your home than the lab ones, and your hot water tank is
| hotter than expected because you like it set hot, and your
| airflow is less than expected because the filter is a bit
| blocked, etc.). Each knocks a few percentage points off the
| efficiency, but the overall impact can be dramatic.
|
| We really need 'smarter' heating systems which can detect and
| correct for such things. For example, water and air pumps which
| measure temperatures and flow rates of air/water, and adjust
| speeds up and down to maintain the optimal efficiency point.
| mrfusion wrote:
| Could this be useful in electric cars? I know they spend a lot on
| heating the cabin.
| hedora wrote:
| Yes; many EVs already use heat pumps, so if this has a higher
| coefficient of power (and is not much heavier), and it can be
| scaled down to automobiles, then it will be a win.
|
| (None of those details can be inferred from the press release.)
| borner791 wrote:
| Clever Deers..
| lucb1e wrote:
| For anyone else confused, this refers to a previous title
| version as per https://news.ycombinator.com/item?id=31791942
| and https://news.ycombinator.com/item?id=31792348 (the comment
| I'm replying to was far above those others for me, so I was
| quite confused)
| visviva wrote:
| Since DOE is an initialism and not an acronym, the capitalization
| in the title is incorrect. It should be "DOE".
| dang wrote:
| Fixed now. Thanks!
| mtlmtlmtlmtl wrote:
| Technology Connections on Youtube has a great video series on how
| heat pumps work, why they're important environmentally and what
| kind of power cost savings they can bring. The second video is a
| longer guide for people who want to get a heat pump.
|
| https://youtu.be/MFEHFsO-XSI https://youtu.be/43XKfuptnik
| reacharavindh wrote:
| I wish governments worldwide would boost this industry and get
| these heat pumps in the hands of people as fast as possible.
|
| I live in the Netherlands that has one of the highest use of
| rooftop solar and generally energy conscious government and
| people. I bought a house recently and while doing some changes
| before moving in, my top priority was to get rid of Gas for
| heating and replace it with an all electric solution and
| supplement the power by as many solar panels as possible. As good
| as my intent is, I literally have EUR25K in the bank waiting to
| be spent for this, and the government gives a subsidy for
| essentially halving the cost of a heat pump, I could not get one
| until day mid next year!!! It is such a disappointment.
|
| The intent is in the right place to encourage people to buy heat
| pumps, people are also willing. However, the chip shortage, and
| the insane labour crisis of qualified people who could install
| this is making the end result unattainable.
|
| My wish is for the European Union to use any emergency powers it
| has to subsidise/mandate/beg the companies to mass manufacture
| heat pumps and solve the installation problem- train more people
| on this trade for free? Make it tax free to earn money by working
| as a heat pump installer? Anything...
|
| Now, there is added incentive in the form of the need to get rid
| of Russian Gas. The time is now. Heat pumps already makes
| economic sense, it helps with climate goals, it boosts economy. I
| wish things happen sooner than later.
| benj111 wrote:
| It's crazy to me that in the west; geo politics, national
| defense, people's budgets, and the economy are all in
| alignment, but no one in power seems to be capitalising on
| that.
|
| Here in the UK we've had nothing like that and seem to be going
| the other way with things like fuel duty cuts.
|
| Another issue here at least is that it seems financially better
| to pair standard heating with battery storage than invest in a
| heat pump.
| orbital-decay wrote:
| I'm actually surprised to see heat pumps gaining so little
| traction in Europe over time, perhaps excluding Baltics. I'm in
| Russia myself and I have a heat pump installed in my house for
| about a decade and a half already. In the long run, it was far
| cheaper than gas in my case. Not to mention it was faster to
| install; the gas pipeline bureaucracy alone would have taken
| several months.
|
| That said, there are environmental concerns about geothermals
| at scale (see the earthquake in Landau). Not sure how much of
| it carries over to residential heat pumps, though.
| porker wrote:
| The "In the long run" bit is the problem. Here in the UK
| people stay in a house for about 10 years before moving. It's
| impossible to get payback on many investments in that time,
| and when you sell your house the improvements aren't valued
| high enough to return the money you spent.
| euroderf wrote:
| P.R. with zero tech details is indistinguishable from 100%
| balonie.
| hedora wrote:
| But it delivers 100% words at 5degF at double the efficiency,
| and 70% to 80% words at -5degF and -10degF. DOE validated the
| performance and efficiency of the press release.
| [deleted]
| kennywinker wrote:
| Great, now if someone can crack the engineering challenge of
| installing a name-brand heat pump for less than $18,000 (CAD)
| that'd be great.
| com2kid wrote:
| Lots of do it yourself videos on YouTube showing installs for
| well under 5k.
|
| Labor is expensive right now. :(
| bbarnett wrote:
| Name brands tend to be unbuyable by the consumer in Canada,
| and if you import one, or buy via grey market, the threat is
| that you have no warranty.
| kennywinker wrote:
| All the quotes I got were for a day of install. I assume it'd
| be one tech, but let's be generous... 2 techs x 8 hours x
| $150/hour = $2400 for labour. So that means either the pump
| itself costs $15k, or somethings wrong in this market.
| kennywinker wrote:
| Or my alternate hot-take (or cold-take?): Great, now if someone
| can crack the engineering challenge of an air-to-water heat
| pump water heater that doesn't turn your basement into a walk-
| in refrigerator, that'd be great.
| ortusdux wrote:
| Rheem, the brand HD carries, is easily ductable. Both the
| inlet and outlet can take 100' of 8" ducting.
|
| I set mine up with T's, electric dampers and some simple
| logic.
| metadat wrote:
| Add a server rack and things will warm up down there.
| kennywinker wrote:
| Make it a liquid-cooled server rack and we can cut out the
| hot water heater entirely
| thrill wrote:
| Run it on solar power and pull the water out of the
| atmosphere and we can save a bundle on running power and
| water.
| ulrikrasmussen wrote:
| Why would it do that? The heat exchanger is placed outside.
| thaeli wrote:
| Heat pump water heaters mostly draw from room air.
| jacobolus wrote:
| Common heat pump water heaters (often called "hybrid") have
| a heat exchanger on the top of the tank, and pull heat out
| of the surrounding air.
| 1123581321 wrote:
| What challenge? Any of the HPWH brands can duct exhaust out
| of the home. Try Sanden if you want more than that.
| kennywinker wrote:
| The all-in-one heat pump hot water heater pulls in warm air
| from its surroundings, pulls the heat out of it and puts
| that into its water. Then it lets out its "exhaust" colder
| air. Ducting to outdoors improves things, because it
| doesn't put that cold air back into your basement / utility
| closet, but you're still pulling heat out of the air -
| which your house heater now has to put back into the air -
| and unless your space is perfectly airtight, that's
| probably just going to be sucked in via the nearest air gap
| to outside.
|
| It's a bad system. Split systems make sense, and I know
| they exist, but they seem weirdly rare.
|
| Some data on this topic:
| https://www.energyvanguard.com/blog/will-a-heat-pump-
| water-h...
| 1123581321 wrote:
| The ducting brings the temperature drop to an almost
| unnoticeable delta. If you are worried, just install it
| near your furnace. It'll eat radiant heat from that
| corner that would otherwise go into the walls, egress
| windows etc. Every other part of the year, you either
| don't mind or benefit from the cooling.
|
| I have the stats from my own Rheem to know I'm coming out
| ahead financially during winter and also haven't seen a
| meaningful swing in the basement climate.
|
| I'm a regular participant in that linked blog, too. :)
| kevstev wrote:
| How cold does it really get? This could be great for a wine
| cellar.
| chrislund wrote:
| Depending on your market, Sanden and Mitsubishi make air-
| source DHW heat pumps where the evaporator/heat source source
| is remote (i.e., outdoor) rather than integrated with the
| tank. I can't speak to Mitsubishi's line but IIRC Sanden has
| the DHW go straight to the outdoor unit, but then you may
| need freeze protection, which I think Sanden provides via
| heat trace. When my current water heater bites the dust, I
| plan on getting a Sanden, and looking in to the feasibility
| of making a glycol loop between the outdoor unit and an
| indoor "indirect" tank to eliminate the need for freeze
| protection.
| kennywinker wrote:
| Thanks for the tip! Where I am Mitsubishis seem to only be
| available through big-name installers, and the only thing
| they offered me when I talked to them was the all-in-one
| style that cools your basement. Living in an old house with
| not great insulation between floors, that was a hard no-go.
| I'm now googling the Sanden ones and getting some promising
| results I hadn't seen before.
| Danieru wrote:
| What you want is an "Ecocute". It is a air source heatoump
| supercritical co2 tanked hot water system. Designed for the
| Japanese market. Without install a 500l tank version costs
| about 1.5k usd in Japan. So you should be able to get one
| installed for about 20k usd in the US. If you beg the HVAC
| guy of course.
| nawitus wrote:
| Why is it so expensive? It's like $1k in Finland.
| kennywinker wrote:
| I have no idea.
|
| You can definitely do it for cheaper. There are $1000-$3000
| single-head units available online for self-install, and you
| could hire an HVAC person to come out and do the high
| pressure line part of it (or all of it) for a similar range.
| It just gets expensive with the name-brand ones. For some
| reason that $2k-6k turns into 10k-20k when you switch to a
| name brand (e.g. mitsubishi). They're only available through
| specific installers, and using a non-authorized installer
| means your warranty is void.
| magicalhippo wrote:
| Maybe we're talking about different things? I'm in Norway
| and we got a Mitsubishi Kaiteki[1] for $1800 total,
| including installation and 25% VAT.
|
| Of course, a multi-room install would probably get
| expensive quickly here too.
|
| [1]: https://kaiteki.no/
| zo1 wrote:
| 36k BTU multi room split unit installs are like 4-5K USD
| here in South Africa, including installation from the
| rough prices I've seen.
| euroderf wrote:
| Units are somewhere over a thou and (simple, not multiduct)
| installation is somewhere under a thou.
| [deleted]
| stormbrew wrote:
| I recently installed a (quite large) heat pump for less than
| that, though it came close. A lot of the cost came from a few
| things:
|
| - the Canada premium: these sorts of things are just more
| expensive here. The base price was just higher than I could
| find in the US, but obviously importing is too expensive. I
| think the reason for this is there's almost no stock.
|
| - adapting my house: the house I live in was built to have
| central air added to it, but even so the pipes going from the
| furnace room to the outside had to be insulated both directions
| instead of only one for an AC. Ripping up our basement ceiling
| to do this added a lot to the cost. An unfinished basement
| would help a lot here.
|
| - HVAC company confusion: I had to go through like five HVAC
| companies before I found one that would believe me that I
| really wanted it. The one I got is a commercial outfit, so
| their prices were just higher. Even they were skeptical but
| they were willing to work with us, and by the end they talked
| about doing more installs so that was nice.
|
| I think the cost for the install and unit itself was $12k for a
| top of line carrier unit capable of working down to pretty low
| temperatures. But we already had a compatible carrier furnace
| and exchanger. Was another couple thousand for ripping up the
| basement, which we had other contractors do.
|
| This was also literally during the heat dome last year. They
| had to ship the unit across the country.
| bitexploder wrote:
| We recently converted our house to 100% heat pumps. The models we
| have are efficient down to like 0F and continue to work down to
| -15F (lower than the record low here). So this tech is novel but
| already consumer available. We have Fujitsu Halcyon XLTH models
| and commercial units that are less common for residential.
| ComputerGuru wrote:
| They all "continue to work" at cold temperatures but the
| question is with what and how much you're going to supplement
| their insufficient heat with when it gets that low.
| bitexploder wrote:
| COP is still decent at low temps. That is the point. They are
| 80% efficient at their lowest temp rating. And, at least
| where we live 99.9% of days will be 100% efficient.
| ComputerGuru wrote:
| I guess 80% efficiency for a few days a year is OK. In The
| Midwest we can go below zero Fahrenheit for a month or more
| at a time and while I happily live with 80-90% furnace
| efficiency with natural gas as a fuel, I certainly would
| never want to do that with electricity as a power source
| (given the historic price difference between the two).
| bitexploder wrote:
| Colorado front range here. We also have a lot of solar
| panels and plenty of credits so that is part of it for
| us.
| dahfizz wrote:
| How does your hot water work?
| bitexploder wrote:
| Heat pump water heater, but that is a totally separate
| system.
| bradleyjg wrote:
| I don't believe in breakthroughs anymore until I see a shipping
| product. I don't care if you are a scientist, company, government
| agency, or NGO same thing applies.
|
| Tell me you've made an incremental improvement and I'll believe
| you, tell me you've made a breakthrough and either you're lying
| or something will prevent it from being realized before
| commercial availability. This is what decades of press releases
| and articles that might as well be press releases have taught me.
| SV_BubbleTime wrote:
| The "save up to $500" in the presser is just so obviously
| fluff. $500 in what home?
|
| And I suspect the magic here is also an air tight new
| construction home with a layout designed around this, not leaky
| everything with an old water heater tucked under the stairs, a
| 30 year old furnace, and R19 insulated walls.
| WithinReason wrote:
| > $500 in what home?
|
| The "up to" part means it's the absolutely largest home you
| can possibly imagine
| pbourke wrote:
| Presumably the 30 year old furnace is replaced or
| supplemented with a new heat pump.
|
| I have realized an approximately $500 yearly savings by
| replacing an older electric tank water heater with a hybrid
| electric (heat pump) water heater so I can believe that
| claim.
| [deleted]
| linsomniac wrote:
| You are right to be skeptical, but in this case the lie is not
| in the performance but that it is a breakthrough.
|
| The announcement is basically: A US company (Lenox) has a
| prototype heat pump that matches performance of Mitsubishi and
| LG heat pumps.
|
| The DOE is running a competition to get US companies to improve
| performance of their heat pumps.
| nfin wrote:
| it might work.
|
| But there exist sooo many prototyping breaktroughs.
|
| Those who follow press releases for many years know that just
| a tiny fraction can transfer this in real world products that
| actually work
|
| (so many more challenges to overcome compared to prototype
| situations!! I don't even know where to begin... every ground
| is different, average person doing the manual work is not as
| skilled and has less support engineers, the guys
| setting/defining the dimensions of various
| recipients/pumps/conduits are often undeskilled and the
| efficiency often lacks tremendously for that reason...)
| linsomniac wrote:
| My thinking on it is: It'd better work, they're just trying
| to catch up to the state of the art. The bigger news would
| be if Lennox _CAN 'T_ make a COP 2 at 5F heat pump. :-
| otter-rock wrote:
| I agree with the general sentiment, but the article explains
| that this "breakthrough" is a product prototype that meets a
| government spec. It's hyperbolic wording, but they're trying to
| warm people up to the idea of eventually getting a heat pump to
| alleviate some energy issues.
| [deleted]
| osigurdson wrote:
| >> The prototype delivers 100% heating at 5degF at double the
| efficiency, and 70% to 80% heating at -5degF and -10degF.
|
| Double the efficiency of what? All existing technology or
| something else? Do they simply mean the COP is 2.0?
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