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"The issue with heat pumps is you may need far less heat at 15c when their very efficient than at -15c when their not." My home is heated with a heat pump. I l

"The issue with heat pumps is you may need far less heat at 15c when their very efficient than at -15c when their not." My home is heated with a heat pump. I live in Canada, and just went through a period of -20C. It works great and is a fraction of the cost of heating with natural gas. It also operates as a fantastic AC in the summer. It uses a closed loop of water to pipes in the ground, with the ground as the "sink". It is very efficient, and the ground is always 8-10C. This conversation seems to be dominated, and moderated, by a lot of people who are in the dark, or misunderstand the fundamental physics behind how a heat pump works, or who gatekeep what "electric" means with heating (which is particularly bizarre).

Retric 7y ago
The ground ends up close to the average temperature of the local environment which in your case is a long way from -15c. Excluding of course hot springs etc, but that’s a separate and very localized solution. Further, if you’re that far south a solar hot water heater system is still cheaper to build + operate and in terms of energy costs. People dealing with permafrost both directly are stuck with lower temperatures and would need to dig much further as your dependent on water exchanging heat with a large thermal mass. That’s the tipping point I am talking about, not your balmy 8-10c average temperatures.
- Marsymars 7y ago
  Only about 35 million people in the entire world are dealing with permafrost.
  - Retric 7y ago
    And people in the tropics have little need for heating. My point is solar hot water heaters are generally the better solution, even if they don’t work in the very far north. But, if you’re that far north heat pumps also fail.
- endorphone 7y ago
  I'm not quite getting your point, and honestly it seems like you're digging deep to stick with what you originally stated. The climate I live in is colder than the majority of humans. Maybe the vast majority. I have a very efficient heat pump (I've been using it for 8 years now -- it's well proven to me by now). Ergo, any notion that heat pumps only work in balmy conditions has no bearing on reality -- yes, those super cheap air exchange units you grab from Home Depot to take the chill off in Atlanta during January might have such limits, but that has no bearing on the market as a whole. The article linked talks about how Germans don't heat with electricity -- even with very efficient heat pumps -- because a regressive tax on such use makes it uneconomical. I don't see what solar heaters (which seldom even pay for themselves in great conditions -- e.g. California -- as an aside) have to do with this conversation.
  - Retric 7y ago
    My point is solar hot water heaters are generally the better option for home heating as I have been saying. You may assume I am referring to a specific case but this is very general advice. Including arctic through tropical climate, sea level or extreme altitude, detached single family homes through skyscrapers, building on bead rock vs oceanfront silt. In the tropics at high altitude you can use cheap systems for domestic hot water and minimal heating needs. Colder local temperatures require larger and more complex systems but also increase demand for heat. Meanwhile, heat pumps get steadily worse until ground source heating becomes viable though at significantly higher upfront costs and more limited locations. Salt water for example dramatically increases heat pump costs costs vs fresh water. Large cities often shift things to heat pumps. Though neither system is that great for dense NYC skyscrapers or other large northern cities. And most cites skyscrapers have significant unused exposures where solar collectors are at least somewhat viable. Many short apartment buildings in China for example have solar collectors for the top few floors. PS: That said, it’s generally not exactly a dramatic difference. However, unlike many things it’s both generally if not always cheaper and more environmentally friendly.
    - Retric 7y ago
      I assume there is zero chance of you reading this, but just felt the need to clarify something. When the efficiency of a heat pump decreases it’s producing less heat for the same energy (when running) rather than the same heat using more energy. As you need more meat output as the temperature drops that quickly becomes a problem. This means you quickly need either a larger heat pump or a backup resistive heating element in the worst conditions. That’s rarely an issue for ground source heating, but is a huge issue than means a heat pump may theoretically be much more effect looking at a chart than what actually happens in practice.
nottorp 7y ago
So it only works when you live in a house on the ground, not in an apartment building.

Retric 7y ago

The ground ends up close to the average temperature of the local environment which in your case is a long way from -15c. Excluding of course hot springs etc, but that’s a separate and very localized solution. Further, if you’re that far south a solar hot water heater system is still cheaper to build + operate and in terms of energy costs. People dealing with permafrost both directly are stuck with lower temperatures and would need to dig much further as your dependent on water exchanging heat with a large thermal mass. That’s the tipping point I am talking about, not your balmy 8-10c average temperatures.

Marsymars 7y ago
Only about 35 million people in the entire world are dealing with permafrost.
- Retric 7y ago
  And people in the tropics have little need for heating. My point is solar hot water heaters are generally the better solution, even if they don’t work in the very far north. But, if you’re that far north heat pumps also fail.
endorphone 7y ago
I'm not quite getting your point, and honestly it seems like you're digging deep to stick with what you originally stated. The climate I live in is colder than the majority of humans. Maybe the vast majority. I have a very efficient heat pump (I've been using it for 8 years now -- it's well proven to me by now). Ergo, any notion that heat pumps only work in balmy conditions has no bearing on reality -- yes, those super cheap air exchange units you grab from Home Depot to take the chill off in Atlanta during January might have such limits, but that has no bearing on the market as a whole. The article linked talks about how Germans don't heat with electricity -- even with very efficient heat pumps -- because a regressive tax on such use makes it uneconomical. I don't see what solar heaters (which seldom even pay for themselves in great conditions -- e.g. California -- as an aside) have to do with this conversation.
- Retric 7y ago
  My point is solar hot water heaters are generally the better option for home heating as I have been saying. You may assume I am referring to a specific case but this is very general advice. Including arctic through tropical climate, sea level or extreme altitude, detached single family homes through skyscrapers, building on bead rock vs oceanfront silt. In the tropics at high altitude you can use cheap systems for domestic hot water and minimal heating needs. Colder local temperatures require larger and more complex systems but also increase demand for heat. Meanwhile, heat pumps get steadily worse until ground source heating becomes viable though at significantly higher upfront costs and more limited locations. Salt water for example dramatically increases heat pump costs costs vs fresh water. Large cities often shift things to heat pumps. Though neither system is that great for dense NYC skyscrapers or other large northern cities. And most cites skyscrapers have significant unused exposures where solar collectors are at least somewhat viable. Many short apartment buildings in China for example have solar collectors for the top few floors. PS: That said, it’s generally not exactly a dramatic difference. However, unlike many things it’s both generally if not always cheaper and more environmentally friendly.
  - Retric 7y ago
    I assume there is zero chance of you reading this, but just felt the need to clarify something. When the efficiency of a heat pump decreases it’s producing less heat for the same energy (when running) rather than the same heat using more energy. As you need more meat output as the temperature drops that quickly becomes a problem. This means you quickly need either a larger heat pump or a backup resistive heating element in the worst conditions. That’s rarely an issue for ground source heating, but is a huge issue than means a heat pump may theoretically be much more effect looking at a chart than what actually happens in practice.

nottorp 7y ago

So it only works when you live in a house on the ground, not in an apartment building.