Although large windows and glass doors open up your living space and allow radiant sunlight to flow in, they can be a source of heat buildup in the house. In winter, sunshine streams through glass and warms up your cold rooms. But in the summer, large surface areas of glass directly exposed to the sun’s rays heat the interior of the house directly, and also indirectly by heating the walls and other exposed surfaces of the house. Minimizing solar gain can help keep your home cooler.

Ventilation is the exchange of indoor and outdoor air in your home. Without proper ventilation, an otherwise insulated and airtight house can hold moisture, causing high humidity levels that can raise indoor temperatures. Most modern homes are designed to be as air-tight as possible, which minimizes uncontrolled air movement in and out of the space. Moving air can remove heat from your home and help create a wind chill effect that cools your body.

The opposite of inadequate insulation, gaps and cracks in your home can leak warm air into your home and increase heat and humidity levels. Finding and blocking these leaks can help reduce the amount of warm air leaking into the house and keep the cool air in.

If your house has AC and you still think your house is too hot, you may have the wrong size AC for your space. An AC unit that is too small will have trouble cooling the entire space efficiently. An oversized air conditioner will cool all the air before it removes the humidity properly and that moisture will make you feel hotter.

Using appliances like your oven can make the house feel hotter. Cooking, laundry, and showering can contribute to humidity levels. Minimizing use of appliances that create heat and reducing humidity in the home can cool it down.

The most common cause of heat trapped in the house is poor insulation, especially in older homes. The sun’s radiant energy quickly heats the roof and much of this heat is transmitted through the roofing materials to the attic side of the roof. That hot air in the attic can radiate down into rooms below it if there is not enough insulation, or if the attic is not properly air sealed.

South and west facing walls have high exposure to direct sun. If they are uninsulated or poorly insulated, the heat from the sun can radiate through the walls and heat up your home.

High thermal mass materials like concrete, bricks, stone and tiles absorb and store heat and can take longer to cool to a lower temperature. It takes longer for these materials to release the heat stored in them and can be a reason your house is so hot. However, if they aren’t exposed to direct sunlight, they will stay cool and help keep the temperature more bearable. The most common use of high thermal mass materials in homes is flooring, walls and countertops.