Hot days are uncomfortable — and sometimes they’re deadly.

“Elderly people in particular are very vulnerable to heat,” says Susan Mazur-Stommen of Indicia Consulting, an environmental research and consulting firm. “And also people with other health vulnerabilities, such as diabetes, asthma … can have difficulties when it gets very hot.”

Mazur-Stommen says air conditioning is a critical tool for keeping people safe in extreme heat. But air conditioners use a lot of energy, and for many people, they can be too expensive to run all the time.

So as part of a project led by Lawrence Berkeley National Laboratory, her firm conducted interviews and focus groups with residents in Fresno about some of the lower-cost methods they use to stay cool.

“A great example from our Fresno research was that people are using blackout curtains,” Mazur-Stommen says. “And they really, really cut heat very, very well.”

She says fans can also improve people’s comfort.

These strategies do not replace the need for air conditioning when it’s dangerously hot, but they may help reduce how much the AC needs to run.

So Mazur-Stommen says they can help make it more affordable for people to protect themselves from the heat.

This article was reported by Sarah Kennedy with ChavoBart Digital Media and originally published by Yale Climate Connections. It is reprinted here under a Creative Commons licensing.