How It Works

Many homeowners don’t realize how important a home’s exterior doors can be. Newer doors often fit and insulate better than older models. You could save significantly on your heating and cooling costs with a new energy efficient door.

When selecting doors, consider energy performance ratings. You may come across doors rated for “U-factor”, “solar heat gain coefficient” and “air leakage”.

• U-factor: This rating measures the amount of non-solar heat that flows through a door. Look for a door with a low U-factor to retain heat in the winter.
• Solar heat gain coefficient (SHGC): This rating measures the amount of solar heat that flows through a door. A high SHGC door is more effective at collecting solar heat during the winter to keep your home warm. A lower SHGC door transmits less heat, so it’s best at keeping your home cool during the summer.
• Air Leakage: This rating measures how much air is able to pass through the door. A low leakage rating is ideal; it lowers heating and cooling costs by retaining air inside your home. 

What Can Go Wrong?

Over time, your doors’ worn out seals can cause efficiency issues. Conditioned air is able to escape, humidity is able to enter, and water may leak inside your home. Seals and weather-stripping should be replaced when you notice any leakage. Wooden doors can crack and splinter over time when exposed to the outdoors. Exterior doors should be treated or painted to extend their life and improve efficiency as well as appearance.

Environmental Impact

Doors come in all sizes depending on their application and use. They can have a negative impact on your carbon footprint as air exchanges through leaks. This indirectly produces more carbon dioxide (CO₂). Energy Star doors can lower energy bills and save money.

Doors can gain and lose heat in any of the following ways:

• Direct conduction through the glass, frame or door material.
• Radiation of heat into and out of the house.
• Air leakage through and around doors.