Seattle's among least air-conditioned cities. But why?

Seattle city skyline from Gas Works Park in Fremont. (File photo: KIRO 7 News)

For those sweltering in their apartments as Seattle warms up this summer, you're not alone.

As 85 percent of apartment units nationwide provide residents with a break from the summer heat, only 20 percent of rental units in Seattle come with primary air conditioning, according to the U.S. Census.

So why is Seattle among the least air-conditioned places in the country?

Multiple factors play into it, such as Seattle landlord-tenant laws that don't require air conditioning like they do heating. But local engineers said it comes down to cost effectiveness in a city with relatively mild year-round temperatures.

"Electricity is cheap in Seattle," engineer Chris Wright, who works for a Lynnwood consulting firm that provides energy-related solutions, said.

"Therefore [property managers] put in the cheapest form of heat and install a resistance heater [like a baseboard]. Those are $200 or less to install in a room. Whereas air-conditioning [installment] is $2,000 minimum."

Many renters are taking air conditioning into their own hands and installing smaller units.

A few years ago, KIRO 7 News spoke to a woman who made her own air-conditioning unit for under $20 by using a foam cooler, fan and ice block.

More homes and apartments are now have air conditioning because of a new statewide code that
requires a single-family home's largest room have a heat pump, which is a refrigeration system that can be reversed to either heat or cool a controlled space.

A recent report from the Seattle Times found that historically, only 6 percent of apartments in the Seattle metro area came with central air conditioning, but that has increased fourfold this decade. The Times attributed the spike in air conditioning to apartment advertising -- as it gets warmer, more property managers are marketing air conditioning as an amenity.