4 ms·

You are going to need to provide a source for your claim that cooling is less efficient than heating. AFAIK from my days as a mechanical engineer, heating from

by dktoao 4y ago

You are going to need to provide a source for your claim that cooling is less efficient than heating. AFAIK from my days as a mechanical engineer, heating from an electric source is ~95% efficient and cooling is ~30% efficient...

coryrc 4y ago
Heat pumps have COP of 2-4, so in either heating or cooling mode, they generate more heating/cooling than electricity used. But the reason cooling is cheaper is the temperature differential. AZ might get to, say, 110°F peak (and far cooler at night), for a temp delta of 35°F while the Midwest will stay below 20°F for months, and even colder at night, for a temp differential no better than 50°F during the day and 60°F at night.
- Scoundreller 4y ago
  And heat pump efficiency takes a dump when it has to go through defrost cycles in heating mode at near/below freezing temps. In cooling mode they provide a source of fresh-distilled water! It always bothered me when air conditioners just dump that water down the sanitary drain instead of pumping it in a garden or misting it on the outside coils.
  - coryrc 4y ago
    Yeah, air source has problems at cold temperatures, especially if they cheap out on ice detection. Fresh is not the word I would use for condensate. Try drinking some of you disagree :). It's corrosive for metal,{EDIT: maybe I just have that confused, see replies} which is why it usually doesn't find a purpose, but you could run it to plants. I have a window A/C which uses it for cooling the outside coils though.
    - Scoundreller 4y ago
      Still wouldn't drink it unless I'm desperate, but I don't see why it would be corrosive. Maybe slightly basic from being in contact with metals, but it couldn't be much unless your coils and fins are disappearing before your eyes. Legionella is a concern though. https://www.environmentalleader.com/2013/01/air-conditioning-condensate-recovery/ https://www.environmentalleader.com/2013/01/air-conditioning...
      - coryrc 4y ago
        I think it's the lack of minerals? But it obviously forms on metal coils to begin with. Maybe I'm confusing it with condensate from condensing natural gas burners.
- clairity 4y ago
  > "...they generate more heating/cooling than electricity used." that's thermodynamically impossible. @dktoao, being a mechanical engineer, surely understands this, and made a statement that is different, and more plausible. COP is a ratio of change in energy (e.g., temperature) produced against a common benchmark (running electricity through a resistive element, for example). that's how it can be greater than 100%. absolute efficiency (what @dktoao offered) compares against a 100% conversion of energy from one form (or place) to another. in this case, you cannot beat 100% (or generally get super close) due to the 2nd law of thermo.
  - coryrc 4y ago
    Basically no common A/C is 30% efficient in any sense of the word. There's a scenario where you can argue it can get as low as 50%, but no common A/C I have ever heard of is using moving less than 2x heat power as electricity power used. 30% is wrong no matter how you cut it. And, "efficiency" doesn't matter. COP does. COP is what is reflected on your electrical bills.
    - clairity 4y ago
      it's basic thermodynamics. you mixed the two, as i explained previously, and now you're leaning into the misconception, rather than acknowledging the difference.
      - coryrc 4y ago
        In no way is anything you said in either post of use to anyone. If I am in my house, use 1000 W of electricity, get 3000 W of heating, that is what is important. No shit the extra heat comes from the environment. It doesn't matter unless you live within a house completely located inside an artificial climate-controlled area, which applies to... none. No houses.
gnu8 4y ago
It is two different modalities of heating though. Electrical heating is 95% efficient at dumping energy from the grid into your house, but a heat pump is using energy from the grid to concentrate and move heat from outside the house to the inside (which is itself unintuitive to people when it is already much colder outside the house than inside). So how do you develop a fair comparison of the two in total energy expended to keep the building at the desired temperature?
dmpk2k 4y ago
Probably heatpumps, depending on the climate. Heatpump effectiveness drops off rapidly as you head below 0C. Considering the temperature extremes that southern US versus northern US housing experiences over the entire year, it's probably easier to keep the southern house around 21C than the northern one.
s1artibartfast 4y ago
Swamp coolers can be several hundred percent efficient.
legitster 4y ago
https://iopscience.iop.org/article/10.1088/1748-9326/8/1/014050 https://iopscience.iop.org/article/10.1088/1748-9326/8/1/014... https://zeroenergyproject.org/warmer-climate-construction-design-considerations/ https://zeroenergyproject.org/warmer-climate-construction-de... https://www.eia.gov/consumption/residential/reports/2009/state_briefs/ https://www.eia.gov/consumption/residential/reports/2009/sta... Sure, but in a cool climate you need much less cooling to be comfortable than you need heating in even a neutral climate.

by dktoao 4y ago

coryrc 4y ago

Heat pumps have COP of 2-4, so in either heating or cooling mode, they generate more heating/cooling than electricity used. But the reason cooling is cheaper is the temperature differential. AZ might get to, say, 110°F peak (and far cooler at night), for a temp delta of 35°F while the Midwest will stay below 20°F for months, and even colder at night, for a temp differential no better than 50°F during the day and 60°F at night.

Scoundreller 4y ago
And heat pump efficiency takes a dump when it has to go through defrost cycles in heating mode at near/below freezing temps. In cooling mode they provide a source of fresh-distilled water! It always bothered me when air conditioners just dump that water down the sanitary drain instead of pumping it in a garden or misting it on the outside coils.
- coryrc 4y ago
  Yeah, air source has problems at cold temperatures, especially if they cheap out on ice detection. Fresh is not the word I would use for condensate. Try drinking some of you disagree :). It's corrosive for metal,{EDIT: maybe I just have that confused, see replies} which is why it usually doesn't find a purpose, but you could run it to plants. I have a window A/C which uses it for cooling the outside coils though.
  - Scoundreller 4y ago
    Still wouldn't drink it unless I'm desperate, but I don't see why it would be corrosive. Maybe slightly basic from being in contact with metals, but it couldn't be much unless your coils and fins are disappearing before your eyes. Legionella is a concern though. https://www.environmentalleader.com/2013/01/air-conditioning-condensate-recovery/ https://www.environmentalleader.com/2013/01/air-conditioning...
    - coryrc 4y ago
      I think it's the lack of minerals? But it obviously forms on metal coils to begin with. Maybe I'm confusing it with condensate from condensing natural gas burners.
clairity 4y ago
> "...they generate more heating/cooling than electricity used." that's thermodynamically impossible. @dktoao, being a mechanical engineer, surely understands this, and made a statement that is different, and more plausible. COP is a ratio of change in energy (e.g., temperature) produced against a common benchmark (running electricity through a resistive element, for example). that's how it can be greater than 100%. absolute efficiency (what @dktoao offered) compares against a 100% conversion of energy from one form (or place) to another. in this case, you cannot beat 100% (or generally get super close) due to the 2nd law of thermo.
- coryrc 4y ago
  Basically no common A/C is 30% efficient in any sense of the word. There's a scenario where you can argue it can get as low as 50%, but no common A/C I have ever heard of is using moving less than 2x heat power as electricity power used. 30% is wrong no matter how you cut it. And, "efficiency" doesn't matter. COP does. COP is what is reflected on your electrical bills.
  - clairity 4y ago
    it's basic thermodynamics. you mixed the two, as i explained previously, and now you're leaning into the misconception, rather than acknowledging the difference.
    - coryrc 4y ago
      In no way is anything you said in either post of use to anyone. If I am in my house, use 1000 W of electricity, get 3000 W of heating, that is what is important. No shit the extra heat comes from the environment. It doesn't matter unless you live within a house completely located inside an artificial climate-controlled area, which applies to... none. No houses.

gnu8 4y ago

It is two different modalities of heating though. Electrical heating is 95% efficient at dumping energy from the grid into your house, but a heat pump is using energy from the grid to concentrate and move heat from outside the house to the inside (which is itself unintuitive to people when it is already much colder outside the house than inside). So how do you develop a fair comparison of the two in total energy expended to keep the building at the desired temperature?

dmpk2k 4y ago

Probably heatpumps, depending on the climate. Heatpump effectiveness drops off rapidly as you head below 0C. Considering the temperature extremes that southern US versus northern US housing experiences over the entire year, it's probably easier to keep the southern house around 21C than the northern one.

s1artibartfast 4y ago

Swamp coolers can be several hundred percent efficient.

legitster 4y ago

https://iopscience.iop.org/article/10.1088/1748-9326/8/1/014050 https://iopscience.iop.org/article/10.1088/1748-9326/8/1/014... https://zeroenergyproject.org/warmer-climate-construction-design-considerations/ https://zeroenergyproject.org/warmer-climate-construction-de... https://www.eia.gov/consumption/residential/reports/2009/state_briefs/ https://www.eia.gov/consumption/residential/reports/2009/sta... Sure, but in a cool climate you need much less cooling to be comfortable than you need heating in even a neutral climate.