Lately, it seems that I’ve been finding air conditioners juxtaposed with temperature sensors for USHCN climate stations of record all over the USA.
That got me to wondering; what sorts of trends are there for air conditioners in the United States? And, could there possibly be any correlation between surface temperature measurements to the number of air conditioners in use in the USA?
Some research led me to a Dept. of Energy’s “Energy Information Administration” (EIA) website which had some interesting facts, some of which I’ve graphed to show trend.
The EIA website only had data as current as 1997 for some reason, but it did go back to 1978, though apparently surveys weren’t done every year.
By 1997, nearly three-quarters (72 percent) of all American households had air-conditioners. 47 percent of all households had central air-conditioning systems and 25 percent had window/wall air-conditioners. 1 percent had both central and window/wall air-conditioners. I would expect that number to be at 80 percent or higher by 2007, in part due to the availability of very inexpensive a/c units manufactured in China, Taiwan, and Korea, some of which can be had for about $100 US.
By 1997, over nine-tenths (93 percent) of the households in the South Atlantic Census Division had air conditioners. Over half (54 percent) of all the households in the division had air conditioners and used them all summer.
From 1978 to 1997, the total amount of electricity used in the residential sector increased from 2.47 quadrillion Btu in 1978 to 3.54 quadrillion Btu. Over the same period, electricity used for residential air-conditioning rose from 0.31 quadrillion Btu to 0.42 quadrillion Btu. Among the reasons air-conditioning electricity use did not rise more is the increasing efficiency of air-conditioning equipment. You can see the electric use trend in the graph below:
This correlates somewhat with the number of cooling degree days, but surprisingly, the trend went downward over the last few years of the study:
The gap between the “haves” and the “have nots” when it comes to air conditioning has been steadily closing. Interestingly, the trend of households with a/c units looks similar to some of the surface temperature trends that have been published:
But it makes you wonder, what effects do the millions of air conditioners dumping waste heat into the near surface atmosphere have on temperatures measured at about the same elevation as the waste heat is dumped? Is there enough atmospheric mixing to distribute it so that it becomes part of the entire UHI bias, or does it dwell in “pockets”? Sounds like a start for a study for somebody.