Air conditioning demand rises due to climate change

NBC Universal, Inc.

As the planet warms and both scorching days and sweltering nights occur more often, more air conditioning is needed to keep homes, schools, offices and hospitals at comfortable temperatures.

Cooling demand is reflected in a temperature-based metric called cooling degree days, or CDD, in which the values estimate how much cooling is needed to maintain a comfortable indoor air temperature.

CDD values are the difference between a location’s daily average outdoor temperature and 65 degrees Fahrenheit, an engineering standard that is considered the ideal indoor temperature.

In 1970, San Jose had a little less than 600 CDDs compared to now, when the metric indicates about 750 CDDs. Considering more than half of the homes in San Jose were built in the 1970s and 1980s when temperatures were much cooler, it's not surprising many don’t have central air conditioning.

The observed rise in cooling demand since 1970 is a trend that’s likely to continue as the planet warms. In the U.S., projected changes in CDD are expected to drive a 71% increase in household cooling demand by 2050, according to the U.S. Energy Information Administration’s latest outlook.

Commercial buildings meanwhile are projected to see a 30% increase in cooling demand over the same period. Those projections are likely underestimated because they’re based on air temperature and therefore don’t account for additional cooling demand due to humidity.

Rising demand for cooling isn’t limited to the U.S., where 90% of households already have air conditioning. Globally, cooling demand is expected to more than triple by 2050, consuming as much electricity as all of China and India today, as countries around the world heat up and gain access to air conditioning.

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