How to keep your home cool in the summer by preventing heat gain 

Reducing the amount of heat that enters your home during summer will help you reduce the cost of air conditioning and keep your home more comfortable. Your home’s walls, windows, doors and ceilings work to insulate its interior living space, so the energy efficiency of those components can impact your cooling and heating costs. 

Here are several things you can do to reduce heat gain in your home: 

Windows 

Windows account for almost half of your home’s heat gain in the summer. Be sure to:

• Shade all sunstruck windows with shade screens, awnings, trees and shrubs on the outside and window tints or film, blinds, shutters or drapery on the inside. Shaded windows can save up to 25% of the cost of air conditioning when compared to unshaded windows. 
• Compare the ratings of window coverings before buying. The effectiveness of a window covering is measured by its shading coefficient. The lower the shading coefficient, the more effective the material is at blocking the sun. 
• Close draperies and blinds on summer days to help keep out the heat. 
• Weatherize your windows to stop air from leaking in. Watch the video below to learn how.

How to weatherize your windows

Walls and doors 

• Paint exterior walls a light color. It will help reflect the sun and prevent your home from absorbing as much heat, thereby keeping it more comfortable inside. 
• Weatherize your doors to prevent cool air from escaping. Watch the video below to learn how.

How to weatherize your doors

Weatherization 

• Inspect weather stripping around exterior doors and windows to ensure cracks are sealed and air isn’t leaking into your home. 
• Caulk around window frames and all exterior wall penetrations such as pipes, electrical boxes and vents. 
• Install foam or rubber receptacle gaskets on all switches and outlets. 
• Keep windows and doors shut tightly to retain cooled air. 
• Check pet doors to make sure they are snug and replace the rubber gaskets as they become worn. 
• Check the fireplace damper to make sure it’s closed and that no daylight can be seen around the edges. 

Insulation 

Insulation provides a line of defense between attic temperatures and the comfort of your living space. The effectiveness of an insulation material is measured in R-values. Typically, the higher the R-value, the more effective the material is at reducing heat transfer. 

• Maintain minimum insulation levels of R-19 for exterior walls (total wall system) and R-30 in your ceiling. 

Internal heat sources 

Internal heat is the heat given off by incandescent lights, appliance motors, television screens, cooktops, washers and dryers, and even our bodies. 

• Avoid activities that can add excessive heat to your home during the hottest part of the day, such as cooking, doing laundry or running the dishwasher. 

Ceiling 

Attic ventilation and insulation affect the amount of heat that is transferred from your attic through your ceiling and into your living space. 

• Make sure your attic is properly ventilated. Without proper ventilation, attic temperatures can reach 140–160 degrees. Such high temperatures not only increase air-conditioning costs but can also reduce the life of your roofing material. 
• Check that attic exhaust vents are not blocked. Before installing an electric attic fan, calculate whether its motor won’t use more electricity than it saves. 

DIY projects to prevent summer heat gain 

Preventing summer heat gain is just one way to improve your home’s energy efficiency. Learn more about DIY projects and ways to reduce the amount of energy your home uses.