A Building Engineer’s Tips for Keeping Cool in Hot Weather

Whether you’re dialing down the thermostat, hoisting a window unit into place or creating a wind tunnel of fans, it’s been a challenge to keep cool during record temperatures this summer.  And comfort comes at a cost -no matter how you choose to cool down. Dr. Jin Wen, an associate professor in College of Engineering and one of three co-directors of Drexel’s Building Science & Engineering Group, has some suggestions for keeping your cool without breaking the bank.

Wen’s research focuses on making buildings more energy efficient and she contends that the key to being energy efficient is working with your natural environment, rather than fighting against it. Here are a few of her tips on how to do this:

Monitor the outside temperature at night. When it drops below the inside temperature and when the outside is not too humid, open the windows and use fans to pull in the cool air. This is called a “night purge.”  “Make sure that you close the windows when the temperature rises up during the daytime to keep the coolness,” Wen said. “This is especially effective for heavy buildings, such as those old stone buildings.”

During the day, help isolate your interior space from the sun’s rays by drawing the curtains or using an external window shade. “[An] External window shade is much more effective than internal ones because once the shortwave sun rays pass through the window, they become long-wave ones and often get trapped inside.” Wen said. “In terms of internal shading, light colored ones are better. An opaque white roller shade can block nearly 60 percent of the solar load from getting into your room.”

Avoid using your stove or oven. You can reduce internal “heat load” by heating water in the microwave or a hot pot instead of the stove top. Try grilling outside more instead of cooking on a burner or baking. “We grill a lot and eat a lot of cold dishes in the summer,” Wen said, “You will spend about 600 -1000 extra watts to cool down the heat generated from a typical two- burner cooking stove or an oven.”

Upgrade your window unit. “It is worthwhile to replace your old window air conditioner with a newer one. New units use about 10-20 percent less energy than older ones, ” Wen said. She also suggests looking for an Energy Star unit with a season energy efficiency ratio (SEER) greater than 10.

If your house that has an attic, make sure it’s ventilated.  Because heat rises, it can build up in the attic and become a heat source itself – making it more difficult to cool the house.

Think about turning on a fan before switching on the AC. “A fan uses much less energy.  If you’re using air conditioning –especially central air- try setting the room temperature to be a bit higher, like 78, and combining it with a personal fan,” Wen said. “The total energy usage will still be much less than cooling the entire space to a lower temperature.”

Wen and the BSEG team are developing new approaches and software tools to aid sustainable building design and looking at ways to retrofit buildings to make them more energy efficient. For more information about their work visit http://bseg.cae.drexel.edu/