How air-conditioning created the modern city

Re:How air-conditioning created the modern city by photojosh on Tuesday August 14, 2018 @09:15PM (#17763164)

If we're talking about electrical heating, this is only true for resistive heating, which is indeed all "waste heat". But many air conditioners can run in "reverse cycle" [0], where you're transferring outside heat back in, and is much more efficient, apparently 50% cheaper to run in electricity costs.

When you run one of these systems, your New Englander and Arizonan are virtuous to the degree of the difference between inside and outside temperatures. ;)

There's even now some combined cycle AC systems which use the extracted heat to generate your hot water [1], sadly not yet available/cost-effective for small residential installations, but they're only off by a factor of 2 now (8kW is the smallest system I've seen, my central air is 4kW).

[0] https://en.wikipedia.org/wiki/Heat_pump [1] http://www.mitsubishielectric.com.au/air-to-water-hot-water-...

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Re:How air-conditioning created the modern city by jdmichal on Tuesday August 14, 2018 @11:42PM (#17763596)

I actually just replaced a 20-year-old AC system that had a link to the hot water system. Installers just removed the water heater link entirely. Said that the extra resistance and energy involved in the exchange cost more than just venting the heat in modern systems with high SEER ratings. No idea if that's accurate; just what I heard.

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Re:How air-conditioning created the modern city by rconti on Thursday August 16, 2018 @11:36AM (#17775573)

Sorry, I meant both resistive AND combustion (eg, "gas"). Now, obviously, natural gas is far cheaper than electric for heat in most of the US at least, but it's all 'generated' heat, with all of the waste heat and CO2 emissions that entails.

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