Monday, April 22, 2013

Heating and Cooling Buildings after the Climate has Changed

Air conditioning versus heating: climate control is more energy demanding in Minneapolis than in Miami(5 page pdf, Michael Sivak, Environ. Res. Letters, Mar. 27, 2013)

Also discussed here : Cold Cities Less Sustainable Than Warm Cities, Research Suggests(Science News, Mar. 26, 2013)

And here: Hot cities more sustainable than cold ones, study says(Science on NBC news, John Roach, Mar. 27, 2013)

The issue reviewed today concerns the differing challenges of heating and cooling buildings in warmer and colder climates and what this might imply with rising temperatures as a result of climate change. Results indicate that it takes more energy to heat a room than to cool it, due to the technologically superior efficiency of air conditioners vs furnaces. This, in turn, points to a positive trend in sustainable energy terms for cities in cold climates, such as Ottawa (the second coldest capital city in the world to Ulan Bator, capital of Mongolia), as long as the relative warming and cooling efficiencies remain the same. That noted, the research did not consider the energy efficiency of geothermal heating which offers emission free heating along with a small energy cost for electricity to power the circulation of the heated air. cold climate  

Key Quotes:

 “climate control in the coldest large metropolitan area in the country -- Minneapolis -- is about three-and-a-half times more energy demanding than in the warmest large metropolitan area – Miami.. Minneapolis has 4376 heating degree days a year compared to 2423 cooling degree days in Miami.”

 “calculated this difference in energy demand using three parameters: the number of heating or cooling degree days in each area; the efficiencies of heating and cooling appliances; and the efficiencies of power-generating plants”

 "It has been taken for a fact that living in the warm regions of the US is less sustainable than living in the cold regions, based partly on the perceived energy needs for climate control; however, the present findings suggest a re-examination of the relative sustainability of living in warm versus cold climates."

*the efficiencies of heating and cooling appliances (a typical air conditioner is about four times more energy efficient than a typical furnace or boiler primarily because it takes more energy to heat up a room than it does to cool it); the efficiencies of power plants, which generate nearly all the electricity used in cooling and 7 percent for heating”

 “The study doesn't examine what happens as the planet warms, and thus fewer heating days are needed in places such as Minnesota, Buffalo, N.Y., and Portland, Ore., and more cooling days are required in Miami, Phoenix and Las Vegas, but the finding may be a silver lining of global warming”

"you run up against basic physical constraints in a hot place that you don't in a cold place…in a cold place you can build an passive solar house that uses very little energy to heat it, but similar options are lacking for people living in hot climates. And as the climate warms, in the "sun belt there'll be significantly increased cooling demands for the summer,"
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