5 ms·

I’m doubtful about both of these claims (Europe has more heating than the US and that heating is more energy-intensive than AC). The latter seems particularly h

I’m doubtful about both of these claims (Europe has more heating than the US and that heating is more energy-intensive than AC). The latter seems particularly hard to believe given how efficient heating is compared to A.C.

0xCMP 8y ago
It may have to do with where the heat comes from? I live in southern most areas of US, but from what I understand it's common for heating to use Gas/etc. instead of electricity. Therefore they use less "energy" (i.e. Electrical energy) All just a theory
- sampo 8y ago
  The most efficient way to heat would still be generating electricity from gas. You lose 50% of the energy (well, you can still use part of the residual heat for heating, too), but with the electricity, you can run a heat pump that heats with about 400% efficiency. 50% × 400% is still 200%, so twice as good as burning gas for heat.
satya71 8y ago
I don't have the numbers. But intuitively, AC should be less energy as it's energy transfer. Heating is usually directly adding energy to the living environment. You can get heating using heat pumps (some southern US homes have this type) but it doesn't work very well when it's too cold outside. Europe should have more heating than US, with it's more northern location.
- TeMPOraL 8y ago
  Indeed. Heat pumps routinely have efficiencies[0] around 400%-500%, because they're not really "producing cold", they just move energy from one inside to outside (or the other way around). -- [0] - of course that's a specific meaning of "efficiency"; they're still less than 100% efficient in terms of energy expended on moving other energy around vs. theoretical minimum.
- nwallin 8y ago
  Electric heaters are more efficient than traditional air conditioning units. Transferring heat from inside a 80F house to the 110F air outside is not very efficient, only about 30-60%. On the hand, an incandescent light bulb is a ~99% efficient heater. The only energy that is "lost" is the light which is radiated out the window. Space heaters and electric radiators are 100% efficient. Additionally, heat pumps are can be spectacularly efficient when it's warm outside (in which case, who needs a heater) but are still more than 100% efficient when it's cold outside. Waste heat is still heat, after all. The problem with heat pumps is that the quantity of thermal they can put into a house drops dramatically when it's cold outside. When it's extremely cold outside, the only heat you're added to the place you're trying to heat is the waste heat from the unit itself. Swamp coolers can be very efficient "air conditioners" but they only work in extremely dry environments. Heat exchangers that pull cold water from a nearby cold lake (for instance, there are data centers in Chicago that use the lakewater from Lake Michigan) can be highly efficient, but there's a lot of infrastructure involved, and they only work on warm land near cold water.
  - sampo 8y ago
    > Transferring heat from inside a 80F house to the 110F air outside is not very efficient, only about 30-60%. This is wrong. Modern heat pumps can easily have efficiency over 400%.
  - xyzzyz 8y ago
    > Transferring heat from inside a 80F house to the 110F air outside is not very efficient, only about 30-60%. Where did you get this number from?
  - nimos 8y ago
    The coefficient of performance (efficiency) of an AC at that temperature range would still be well over 1. Probably around 3-4 depending on the unit and refrigerant. [0] ACs are very efficient for the same reason heat pumps are efficient. They are just moving energy around. [0] https://www.researchgate.net/publication/242172797_A_Comparison_Of_An_R22_And_An_R410A_Air_Conditioner_Operating_At_High_Ambient_Temperatures https://www.researchgate.net/publication/242172797_A_Compari...
xyzzyz 8y ago
Sure thing. Heating (space + water) represents nearly 80% of EU household energy use[1], compared to 60% in the US[2]. I have no clue what you mean by "heating is efficient compared to AC". In fact, opposite is true -- unless you use some kind of heat pump, which are very uncommon in Europe, you only get exactly one unit of heating per unit of energy consumed. On the other hand, with AC (which _is_ a heat pump), you get something on the order of 5 units of heat (energy) removed per unit of energy consumed. [1] - https://ec.europa.eu/eurostat/statistics-explained/index.php/Energy_consumption_in_households https://ec.europa.eu/eurostat/statistics-explained/index.php... [2] - https://www.eia.gov/energyexplained/index.php?page=us_energy_homes https://www.eia.gov/energyexplained/index.php?page=us_energy...
- skybrian 8y ago
  This way of thinking about efficiency doesn't take into account gains from insulation and/or reducing unnecessary heating. An electric blanket is more efficient than heating a room, which in turn is more efficient than heating a house.
sampo 8y ago
Here is a study from 2013 in Environmental Research Letters. Comparing Minneapolis and Miami, the coldest and the warmest metropolitan areas in the US. Minneapolis uses (per capita) 3.5 times more energy for heating and AC (mainly heating) than Miami (mainly AC). "This finding suggests that, in the US, living in cold climates is more energy demanding than living in hot climates." http://iopscience.iop.org/article/10.1088/1748-9326/8/1/014050/pdf http://iopscience.iop.org/article/10.1088/1748-9326/8/1/0140... Part of the difference is that, heating is usually directly burning oil or gas, so the efficiency is 1:1, whereas cooling can have efficiency 4:1 because heat pumps just move heat. But you need electricity to run a heat pump, and generating the electricity is at about 0.5:1 efficiency. So if all Minneapolis switched to heating with heat pumps, they could bring the difference down from 3.5 to 1.8. But still living in Miami is more energy efficient.
- saltcured 8y ago
  Miami can only be considered "hottest" because it never gets cold and you consider the average. It actually spends a long time near room temperature. Somewhere like Las Vegas or Phoenix gets both hotter and colder. If we arbitrarily pick 70F as room temperature, Miami has a typical annual high/low spread of approximately 60F-90F or -10 to +20 degrees relative to room temperature. Meanwhile, Minneapolis has a typical annual spread of approximately 10F-85F or -80 to +15 degrees relative to room temperature.
  - sampo 8y ago
    You should look at section 2.2 in the article. Miami has more cooling degree days (2423) per year than Phoenix (2327) or Las Vegas (1786).
    - SECProto 8y ago
      Heat transfer, though, is based on temperature differentials - if Miami is +7degrees every day of the year, and Phoenix is +20degrees only 117 days per year, the energy demands of Phoenix for cooling could very easily be much higher (energy lost through walls, roof would be much higher, as would mass transfer of energy when doors open.) This is irrespective of local construction. Add to this, radiative gain (insolation through windows) is not captured in the degree-days statistic, nor is humidity related cooling (condensing water takes a lot of energy!)

0xCMP 8y ago

It may have to do with where the heat comes from? I live in southern most areas of US, but from what I understand it's common for heating to use Gas/etc. instead of electricity. Therefore they use less "energy" (i.e. Electrical energy) All just a theory

sampo 8y ago
The most efficient way to heat would still be generating electricity from gas. You lose 50% of the energy (well, you can still use part of the residual heat for heating, too), but with the electricity, you can run a heat pump that heats with about 400% efficiency. 50% × 400% is still 200%, so twice as good as burning gas for heat.

satya71 8y ago

I don't have the numbers. But intuitively, AC should be less energy as it's energy transfer. Heating is usually directly adding energy to the living environment. You can get heating using heat pumps (some southern US homes have this type) but it doesn't work very well when it's too cold outside. Europe should have more heating than US, with it's more northern location.

TeMPOraL 8y ago
Indeed. Heat pumps routinely have efficiencies[0] around 400%-500%, because they're not really "producing cold", they just move energy from one inside to outside (or the other way around). -- [0] - of course that's a specific meaning of "efficiency"; they're still less than 100% efficient in terms of energy expended on moving other energy around vs. theoretical minimum.
nwallin 8y ago
Electric heaters are more efficient than traditional air conditioning units. Transferring heat from inside a 80F house to the 110F air outside is not very efficient, only about 30-60%. On the hand, an incandescent light bulb is a ~99% efficient heater. The only energy that is "lost" is the light which is radiated out the window. Space heaters and electric radiators are 100% efficient. Additionally, heat pumps are can be spectacularly efficient when it's warm outside (in which case, who needs a heater) but are still more than 100% efficient when it's cold outside. Waste heat is still heat, after all. The problem with heat pumps is that the quantity of thermal they can put into a house drops dramatically when it's cold outside. When it's extremely cold outside, the only heat you're added to the place you're trying to heat is the waste heat from the unit itself. Swamp coolers can be very efficient "air conditioners" but they only work in extremely dry environments. Heat exchangers that pull cold water from a nearby cold lake (for instance, there are data centers in Chicago that use the lakewater from Lake Michigan) can be highly efficient, but there's a lot of infrastructure involved, and they only work on warm land near cold water.
- sampo 8y ago
  > Transferring heat from inside a 80F house to the 110F air outside is not very efficient, only about 30-60%. This is wrong. Modern heat pumps can easily have efficiency over 400%.
- xyzzyz 8y ago
  > Transferring heat from inside a 80F house to the 110F air outside is not very efficient, only about 30-60%. Where did you get this number from?
- nimos 8y ago
  The coefficient of performance (efficiency) of an AC at that temperature range would still be well over 1. Probably around 3-4 depending on the unit and refrigerant. [0] ACs are very efficient for the same reason heat pumps are efficient. They are just moving energy around. [0] https://www.researchgate.net/publication/242172797_A_Comparison_Of_An_R22_And_An_R410A_Air_Conditioner_Operating_At_High_Ambient_Temperatures https://www.researchgate.net/publication/242172797_A_Compari...

xyzzyz 8y ago

Sure thing. Heating (space + water) represents nearly 80% of EU household energy use[1], compared to 60% in the US[2]. I have no clue what you mean by "heating is efficient compared to AC". In fact, opposite is true -- unless you use some kind of heat pump, which are very uncommon in Europe, you only get exactly one unit of heating per unit of energy consumed. On the other hand, with AC (which _is_ a heat pump), you get something on the order of 5 units of heat (energy) removed per unit of energy consumed. [1] - https://ec.europa.eu/eurostat/statistics-explained/index.php/Energy_consumption_in_households https://ec.europa.eu/eurostat/statistics-explained/index.php... [2] - https://www.eia.gov/energyexplained/index.php?page=us_energy_homes https://www.eia.gov/energyexplained/index.php?page=us_energy...

skybrian 8y ago
This way of thinking about efficiency doesn't take into account gains from insulation and/or reducing unnecessary heating. An electric blanket is more efficient than heating a room, which in turn is more efficient than heating a house.

sampo 8y ago

Here is a study from 2013 in Environmental Research Letters. Comparing Minneapolis and Miami, the coldest and the warmest metropolitan areas in the US. Minneapolis uses (per capita) 3.5 times more energy for heating and AC (mainly heating) than Miami (mainly AC). "This finding suggests that, in the US, living in cold climates is more energy demanding than living in hot climates." http://iopscience.iop.org/article/10.1088/1748-9326/8/1/014050/pdf http://iopscience.iop.org/article/10.1088/1748-9326/8/1/0140... Part of the difference is that, heating is usually directly burning oil or gas, so the efficiency is 1:1, whereas cooling can have efficiency 4:1 because heat pumps just move heat. But you need electricity to run a heat pump, and generating the electricity is at about 0.5:1 efficiency. So if all Minneapolis switched to heating with heat pumps, they could bring the difference down from 3.5 to 1.8. But still living in Miami is more energy efficient.

saltcured 8y ago
Miami can only be considered "hottest" because it never gets cold and you consider the average. It actually spends a long time near room temperature. Somewhere like Las Vegas or Phoenix gets both hotter and colder. If we arbitrarily pick 70F as room temperature, Miami has a typical annual high/low spread of approximately 60F-90F or -10 to +20 degrees relative to room temperature. Meanwhile, Minneapolis has a typical annual spread of approximately 10F-85F or -80 to +15 degrees relative to room temperature.
- sampo 8y ago
  You should look at section 2.2 in the article. Miami has more cooling degree days (2423) per year than Phoenix (2327) or Las Vegas (1786).
  - SECProto 8y ago
    Heat transfer, though, is based on temperature differentials - if Miami is +7degrees every day of the year, and Phoenix is +20degrees only 117 days per year, the energy demands of Phoenix for cooling could very easily be much higher (energy lost through walls, roof would be much higher, as would mass transfer of energy when doors open.) This is irrespective of local construction. Add to this, radiative gain (insolation through windows) is not captured in the degree-days statistic, nor is humidity related cooling (condensing water takes a lot of energy!)