3 ms·

COP is not efficiency. Efficiency is what you did / what you had the resources to do in an ideal world. That makes thermal chemical heating 20-50% efficient, t

COP is not efficiency. Efficiency is what you did / what you had the resources to do in an ideal world. That makes thermal chemical heating 20-50% efficient, thermal electric heating 10-30% and heat pumps 50-70% efficient (depending on where you draw the boundaries). You could also draw the limit at reduced carnot efficiency rather than reversibility, in which case heat pumps can be close to 100%

Someone1234 4y ago
This is such pointless pedantry. Heat pumps having an efficiency greater than 1/100% is well known, well publicized, and you're trying to make some artificial distinction here that added nothing to this thread/context/discussion. See: https://physics.stackexchange.com/questions/489467/can-a-heat-pump-have-efficiency-greater-than-100 https://physics.stackexchange.com/questions/489467/can-a-hea... https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/ https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/ I won't be further responding to this sub-topic, since it has nothing at all to do with the UK's inflation/energy prices. Plus frankly I feel like you're trying to confuse people rather than inform, I'd point people to the Department of Energy link above if they want to understand the benefit that modern heat pumps could offer to energy usage.
- Schroedingersat 4y ago
  Characterizing them as >100% efficient is poor communication. It doesn't map to any intuitive understanding, it does not communicate anything about how much heating could be done with that energy (thus leading to people believing absurd claims), and it does not map to either the colloquial or technical meaning of efficiency in any other context. Efficiency as a concept doesn't go over 100% and just because confusing and misleading explanations are the norm doesn't mean they should continue.
  - danhor 4y ago
    > It doesn't map to any intuitive understanding, it does not communicate anything about how much heating could be done with that energy But that's exactly what it does. It's technically wrong, but communicates the understanding that you put 100% of electrical energy into it and get 250-450% of heating energy for your home out of it, as opposed to 100% with resistive heating. That some of the electrical energy comes out of the air outside or from the ground is irrelevant for most people. What are absurd claims you reference?
    - Schroedingersat 4y ago
      No it doesn't. "400%" gives you no indication that the upper bound is 800%. And failing to communicate that the heat comes from elsewhere is condescending and leads to misunderstandings. It also fails to communicate that it's harder to move the heat when it is colder. We have a perfectly valid term that does what yoh want without lying and without anti-education in the name of making it 'easier' which is coefficient of performance. You could even give it a different name to `void the scary word if you want, just don't call it efficiency because it's not.
      - danhor 4y ago
        > gives you no indication that the upper bound is 800%. But it isn't? For e.g. outside sheds (heated to 7°C) the COP can theoretically go up to 27. For solar panels, the highest theoretical efficiency is well below 100% and the bound isn't communicated. > It also fails to communicate that it's harder to move the heat when it is colder. For heating that's less the case, but the efficiency of e.g. solar panels also varies depending on the temperature. That's not exclusive for heat pumps (although much more extreme there). > You could even give it a different name to `void the scary word if you want, just don't call it efficiency because it's not. Few people know what Coefficient of Performance means. If I give choose a new name, even less people will understand it. I try to either put efficiency in quotation marks or explain the concept, but efficiency maps (in the sense of energy I care about in and out) pretty well. I think anti-education is too harsh, I'd describe it more as a white lie. It's the same as saying Mac & Linux systems don't get malware or saying in school maths that you can't take the square root of -1. Wrong, but correct enough for understanding the point and allowing useful reasoning.

Someone1234 4y ago

This is such pointless pedantry. Heat pumps having an efficiency greater than 1/100% is well known, well publicized, and you're trying to make some artificial distinction here that added nothing to this thread/context/discussion. See: https://physics.stackexchange.com/questions/489467/can-a-heat-pump-have-efficiency-greater-than-100 https://physics.stackexchange.com/questions/489467/can-a-hea... https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/ https://dothemath.ucsd.edu/2012/06/heat-pumps-work-miracles/ I won't be further responding to this sub-topic, since it has nothing at all to do with the UK's inflation/energy prices. Plus frankly I feel like you're trying to confuse people rather than inform, I'd point people to the Department of Energy link above if they want to understand the benefit that modern heat pumps could offer to energy usage.

Schroedingersat 4y ago
Characterizing them as >100% efficient is poor communication. It doesn't map to any intuitive understanding, it does not communicate anything about how much heating could be done with that energy (thus leading to people believing absurd claims), and it does not map to either the colloquial or technical meaning of efficiency in any other context. Efficiency as a concept doesn't go over 100% and just because confusing and misleading explanations are the norm doesn't mean they should continue.
- danhor 4y ago
  > It doesn't map to any intuitive understanding, it does not communicate anything about how much heating could be done with that energy But that's exactly what it does. It's technically wrong, but communicates the understanding that you put 100% of electrical energy into it and get 250-450% of heating energy for your home out of it, as opposed to 100% with resistive heating. That some of the electrical energy comes out of the air outside or from the ground is irrelevant for most people. What are absurd claims you reference?
  - Schroedingersat 4y ago
    No it doesn't. "400%" gives you no indication that the upper bound is 800%. And failing to communicate that the heat comes from elsewhere is condescending and leads to misunderstandings. It also fails to communicate that it's harder to move the heat when it is colder. We have a perfectly valid term that does what yoh want without lying and without anti-education in the name of making it 'easier' which is coefficient of performance. You could even give it a different name to `void the scary word if you want, just don't call it efficiency because it's not.
    - danhor 4y ago
      > gives you no indication that the upper bound is 800%. But it isn't? For e.g. outside sheds (heated to 7°C) the COP can theoretically go up to 27. For solar panels, the highest theoretical efficiency is well below 100% and the bound isn't communicated. > It also fails to communicate that it's harder to move the heat when it is colder. For heating that's less the case, but the efficiency of e.g. solar panels also varies depending on the temperature. That's not exclusive for heat pumps (although much more extreme there). > You could even give it a different name to `void the scary word if you want, just don't call it efficiency because it's not. Few people know what Coefficient of Performance means. If I give choose a new name, even less people will understand it. I try to either put efficiency in quotation marks or explain the concept, but efficiency maps (in the sense of energy I care about in and out) pretty well. I think anti-education is too harsh, I'd describe it more as a white lie. It's the same as saying Mac & Linux systems don't get malware or saying in school maths that you can't take the square root of -1. Wrong, but correct enough for understanding the point and allowing useful reasoning.