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The article mentions the most important point towards the end: “The better you insulate, the less heat you need in the first place,” No heat pump will help if
by ashayh 3y ago
The article mentions the most important point towards the end: “The better you insulate, the less heat you need in the first place,”
No heat pump will help if your house is leaky or under insulated.
- anonporridge 3y agoInsulation also matters for keeping your house cool and improving AC efficiency.
- northwest65 3y agoSure they can, you can absolutely use heat pumps to brute force it, been there done that.
- danans 3y agoNot only that, but since a heat pump is at least 3x as energy efficient as the most efficient gas furnace, using one results in about 1/2 the E2E CO2 emissions as the gas furnace when the grid electricity being consumed is natural gas based. If you live in an area with abundant zero emissions electricity, then you are heating without any C02 emissions at all. That said, we should do both heat pumps and insulate better.
- ori_prior 3y agoYour numbers are off. Thermal power plants typically do have a thermal-to-electric efficiency of around 30% (40% max), so with your heatpump having an electric-to-thermal efficiency of an assumed 300%, you end up with basically no difference in CO₂ emissions. Note that there are some misleading efficiency claims for gas plants around 60%, but those are not for thermal-to-electric efficiency but for generating electricity plus district heating from waste heat.
- coderenegade 3y ago60% would be terrible thermodynamic efficiency for a cogeneration plant. Modern CCGT systems crack 60% thermodynamic efficiency for just the electricity generation. With cogeneration, system efficiencies are typically in the 70-80% range.
- ori_prior 3y ago60% is feasible for e.g. nuclear and gas, if you use more than one turbine and there is a big constant temperature differential. This typically isn't the case for gas plants which are intentionally variable and often intended to be cheap to build. While at peak temperature, they might run at peak efficiency around the theoretical maximum of 60% (thermal to electric) with a multi-turbine assembly, typically efficiency is far lower because gas plants usually don't run at peak efficiency and only have one turbine.
- philipkglass 3y agoI don't think that any nuclear reactor has achieved 60% thermal-to-electricity efficiency. In a water cooled reactor the hot side starts with cooler steam than a combustion-fired plant can generate so it's hard to reach really high efficiency. Reactors cooled with helium, molten salts, or liquid metal could theoretically do better but I don't think that any actually-built power reactors have reached 60%. The brand new EPR achieves only 37% thermal efficiency and that is considered a good number for a power reactor: https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/advanced-nuclear-power-reactors.aspx https://www.world-nuclear.org/information-library/nuclear-fu...
- ori_prior 3y agoNo, you are right, 60% is a theoretical maximum achievable maybe with supercritical reactor coolant. The actual maximum for existing reactors is somewhere just below 40%.
- philipkglass 3y agoModern combined cycle gas turbines offer thermal-to-electric efficiency over 60% (on a lower heating value fuel basis) at full design load, e.g. this General Electric system at 64%: https://www.ge.com/news/press-releases/ha-technology-now-available-industry-first-64-percent-efficiency https://www.ge.com/news/press-releases/ha-technology-now-ava... Approximating natural gas as 100% methane, that means the thermal-to-electric efficiency on a higher heating value basis is more like 57-58%: https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_combustion_tables https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_com... Neither of these efficiency measures include district heating with waste heat.
- Turskarama 3y agoKeep in mind that pure gas heating is also not 100% efficient because you need to remove the exhaust, meaning you need to use a heat exchanger and no heat exchanger is 100% efficient either. Some of the heat gets carried outside.
- callalex 3y agoSure but these days even the cheap stuff is around 95% efficient because that enables the use of cheaper plastic exhaust pipes instead of insulated metal.
- spiderice 3y agoYou’re describing my situation. How do you de-leakify a house?
- ashayh 3y agoAero barrier and/or spray foam for an existing home should work well. But they are not long lasting and are often not environmentally friendly. You can also look into exterior insulation. If possible and if you have the funds, try to do a retrofit: https://ekobuilt.com/2019/04/24/retrofitting-an-older-home-to-passive-house-standard/ https://ekobuilt.com/2019/04/24/retrofitting-an-older-home-t... https://www.buildwithrise.com/stories/passive-house-retrofit-is-it-worth-the-investment https://www.buildwithrise.com/stories/passive-house-retrofit... You don't have to do all the the things to improve performance -- you can pick and choose.
- zip1234 3y ago- spray foam around/behind outlets on exterior walls (major leak point) which can be done often by just removing the outlet covers - spray foam around windows (requires removing trim) - caulk joints/spray foam rim joist in basement/crawl space - spray foam around any attic can lights/duct work - make sure ducts and air returns are sealed properly
- tapoxi 3y agoSome home energy companies will do a free audit, in my case it's Mass Save. My in-laws on a limited income even got new windows and insulation for free.
- person8645 3y agoAeroBarrier does the spray insulation strategy all at once for a whole home. Could look into something like that.
- throw0101a 3y ago> You’re describing my situation. How do you de-leakify a house? Do a blower door test and see where the air is coming in/out: * https://www.energy.gov/energysaver/blower-door-tests https://www.energy.gov/energysaver/blower-door-tests * https://www.youtube.com/watch?v=msZ_E-4GFs8 https://www.youtube.com/watch?v=msZ_E-4GFs8 * https://www.youtube.com/watch?v=Q5vHxgq7GKo https://www.youtube.com/watch?v=Q5vHxgq7GKo Then plug the holes.
- MivLives 3y agoThe worst is when you rent. I live in an area that doesn't really expect much cold or heat. All the windows are single paned. The sun beating on the roof raises the top floor to the outside temperature plus 5 degrees. I can't fix any of it because I'm only here for a few years.
- notyourwork 3y agoThis is something to consider for a future rental property.
- bombcar 3y agoSome jurisdictions will actually basically pay the landlord to improve those things, worth checking community block grants and other similar search terms for your location.
- gs17 3y agoRenting is a pain for heat pumps too, why would a landlord spend extra on one when they can pass the cost of utilities on to the tenant?
- autoexec 3y agoIt's kind of nice in cool climates. I've rented places where I never had to turn on the heat once all winter thanks to all the heat coming up from lower floors. Temps were almost always above 60F and usually above 65 which is perfectly fine for cozy sweaters and blankets.
- NiloCK 3y agoI have new heat pumps in a very old, under insulated, and leaky house. I didn't use my oil furnace last winter (the first since two additional pumps). My costs were about half of the previous year, and I'm sure my carbon footprint was much better as well. Can you say more about what your comment is supposed to mean?
- ashayh 3y agoWithout fixing leaks and insulation, you've done the tech equivalent of throwing large amounts of resources at the problem rather than fixing the root cause :) Your CO footprint will be far better if you decided to fix the leaks & insulation. This is a pretty broad topic, and you can watch videos from this channel to learn more: https://www.youtube.com/watch?v=dReyrSGokEQ https://www.youtube.com/watch?v=dReyrSGokEQ There are options to do a full passive house retrofit, or just add exterior insulation if you have the funds and inclination. Plus you can get better air quality with filtered air, lower mold/pollen issues, lower noise if you care about that and overall home comfort. https://www.buildwithrise.com/stories/passive-house-retrofit-is-it-worth-the-investment https://www.buildwithrise.com/stories/passive-house-retrofit...
- cogman10 3y agoNot OP, but my assumption is that better insulation means you need less heating and cooling. I've lived in a home with a literal hole to the outside. During the winter we had to run the radiators non-stop and it was still freezing. If you are trying to save energy, then sealing up and improving insulation will generally have the largest bang for the buck.
- kumarvvr 3y agoThey mean that your bill and footprint would have been even lower if it were better insulated and less leaky.
- mft_ 3y agoOur house (in Europe) is relatively old and not well insulated by modern standards, and all of the advice we read and receive from experts is that heat pumps are not a good fit without additional insulation. The gist is that we’d need to spec larger units and/or run them harder than usual, removing savings vs. gas.
- XorNot 3y agoAnd it's irrelevant. Everyone is like "but if you have better insulation..." well golly gee, guess I'll get right on that. Tearing out all my drywall? Re-sarking my roof? Cost-free! Definitely not hugely disruptive, invasive and expensive activities which stand a good chance of forcing me to move out of my house while the work is complete... People love throwing in about how effective insulation is, completely ignoring the vast difference in difficulty and cost it actually represents.
- ashayh 3y agoThere are other advantages to fixing leaks & insulation such as controlling humidity/moisture, lowering mold/pollen/dust, lower noise, adding better air filtration, maybe even better fire protection. By "lower" I mean you can eliminate some of these issues. Not to mention a far lower energy bill. I would not describe these as irrelevant to most people. Depending on the house, location and condition, adding exterior or interior insulation and/or aero barrier, or spray foam could be more cost effective and not so invasive as you think. https://www.youtube.com/watch?v=_nOI99ew5MM https://www.youtube.com/watch?v=_nOI99ew5MM https://www.youtube.com/watch?v=eYjF1afRqvE https://www.youtube.com/watch?v=eYjF1afRqvE
- smeej 3y agoNever mind that you really, really can't do anything about that if you're renting.
- tharkun__ 3y agoI wouldn't say irrelevant but definitely nuanced. Putting more insulation in the attic does not mean redoing the roof. Depending on what you have it might just be blowing in some insulation or adding matting. Of course there are options like spray foaming but it's not the only one. You are of course right that if your walls are completely uninsulated you will probably want to rip out that dry wall and that will cost you. Maybe blown insulation is an option too depending on your specifics. Do some math and see if it makes sense to do it if you don't want to do it purely for the sake of the planet. Drywalling isn't that big of a deal actually. The worst would be the ceiling and you don't have to touch that. Regular drywall on a wall is easily done solo by a home owner. Been there, done that. It's funny what money makes you do. I had a choice to pay tens of thousands to have professionals do it or pay hundreds for materials and do it myself. I did lots of TIL and I have beautiful white walls again.
- QuarterReptile 3y agoIt's actually exactly the reverse: for a house that's well-insulated, it barely matters how efficient your heating and cooling appliances are, especially if you're considering replacement of working systems.