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How much affect does AC have on increasing the outside air temperature? What and how much direct effect does the heat exchange have? What about the energy requ

by jrs235 9y ago

How much affect does AC have on increasing the outside air temperature? What and how much direct effect does the heat exchange have? What about the energy required to run the units?

Top19 9y ago
In Cairo this is a very big issue. I have heard something like it raising the outside temperature by 15 degrees in the city proper. Those are likely going to be older air conditioners not following the latest standards though, and I don't know what the broader impact beyond Cairo is.
humanrebar 9y ago
I'm not a climatologist, but it's my understanding that pouring concrete and asphalt has a larger effect than A/C units. https://en.wikipedia.org/wiki/Urban_heat_island https://en.wikipedia.org/wiki/Urban_heat_island
jsjohnst 9y ago
Depends on where very dramatically. If the A/C units are venting to the outside, not likely to have a dramatic impact outside the immediate area of the coils. In the NYC subway system however, it apparently had a dramatic impact. From what I read (source not handy), before A/C came to trains the tunnels were relatively ok (<90°F), but since adding A/C to the trains, tunnels and platforms now hit way over 100° (L platform has been >115°) in the summer.
LeoPanthera 9y ago
Energy can't be created or destroyed, only moved around. So the heat generated by an air conditioner can be calculated exactly by how much electrical power it consumes.
- jrs235 9y ago
  I get that. The amount of energy "created" by the AC is the amount that is consumed (electricity). However, AC is also a heat pump, displacing the heat in the air inside a structure to the outside of it. If you calculate all the inside AC air space in New York City and figure out that volume and the amount of the heat displaced, what local affect does it have on the air temperature on the sidewalk?
- benlorenzetti 9y ago
  Your absolutely correct, but I just want to point out that thermal efficiency of an AC unit will be greater than 100%. I.e. it can drive more heat from one reservoir of air to another than the electric electric energy required to do so.

by jrs235 9y ago

How much affect does AC have on increasing the outside air temperature? What and how much direct effect does the heat exchange have? What about the energy required to run the units?

Top19 9y ago

In Cairo this is a very big issue. I have heard something like it raising the outside temperature by 15 degrees in the city proper. Those are likely going to be older air conditioners not following the latest standards though, and I don't know what the broader impact beyond Cairo is.

humanrebar 9y ago

I'm not a climatologist, but it's my understanding that pouring concrete and asphalt has a larger effect than A/C units. https://en.wikipedia.org/wiki/Urban_heat_island https://en.wikipedia.org/wiki/Urban_heat_island

jsjohnst 9y ago

Depends on where very dramatically. If the A/C units are venting to the outside, not likely to have a dramatic impact outside the immediate area of the coils. In the NYC subway system however, it apparently had a dramatic impact. From what I read (source not handy), before A/C came to trains the tunnels were relatively ok (<90°F), but since adding A/C to the trains, tunnels and platforms now hit way over 100° (L platform has been >115°) in the summer.

LeoPanthera 9y ago

Energy can't be created or destroyed, only moved around. So the heat generated by an air conditioner can be calculated exactly by how much electrical power it consumes.

jrs235 9y ago
I get that. The amount of energy "created" by the AC is the amount that is consumed (electricity). However, AC is also a heat pump, displacing the heat in the air inside a structure to the outside of it. If you calculate all the inside AC air space in New York City and figure out that volume and the amount of the heat displaced, what local affect does it have on the air temperature on the sidewalk?
benlorenzetti 9y ago
Your absolutely correct, but I just want to point out that thermal efficiency of an AC unit will be greater than 100%. I.e. it can drive more heat from one reservoir of air to another than the electric electric energy required to do so.