Friday, August 31, 2012

The Future of Air Conditioning

An article from the New York Times was sent to me recently. It described the problems with the energy use of air conditioning in the future as well as attempts to conserve today. Here are a few interesting facts from the article.

- A Japanese study concluded that operating an office a few degrees above “optimum” (72-75°F) resulted in a measured decrease in productivity of between 2 and 5%. If salaries run $200/SFY (square-foot-year average in developed countries), and one loses 2% productivity, that is $4/SFY. It is estimated that the average cost to heat and cool a building is about $2/SFY. It is easy to see that operating a building above a desirable setpoint is a losing proposition.

- In Japan, with the lack of nuclear power, some buildings were operated at 80°F+, to save energy. Occupants were using fans to be able to continue to work. Data showed energy use was greater than when operated at more ideal temperatures! It turns out that many buildings are mostly made up of interior spaces and the setpoint is pretty much independent of the temperature difference between the inside and outside, but wholly dependent on the internal heat gain, which must be removed when outside temperatures are above whatever setpoint is established (where outside air cannot be used to cool a building).

- Air conditioning is directly related to productivity in hot climates, where most humans now live. It was estimated that a billion (yes, a billion) folks will be entering the consumer market in the next 15 years. It is further estimated that one of their first purchases will be an air conditioner. If this proves true, providing power to run those AC units will be a real challenge; conservation and thoughts of “carbon footprints” in the US will pale in comparison to the expected increase in just over a decade.

This should be an interesting decade...

Authored by: Dan Int-Hout, Chief Engineer Krueger