Are Your Energy Costs Going Through Your Roof?

Written by Tony Rubeo
Updated June 15, 2021
By properly insulating your attic you can keep warm air from escaping and save money on your energy bills. (Photo courtesy of Vinay S. of North Brunswick, New Jersey)

Hot air rises … but good insulation can keep your energy costs from doing the same thing.

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Did you know that nearly half of the money you spend on utility bills goes toward heating and cooling your home, according to the U.S. Department of Energy?

Inside your home, energy costs are going through your roof.

Why is this happening?

Going up

We know hot air rises. It absorbs energy in the form of heat and this makes molecules in air move and expand, decreasing the air's density.

The opposite is true for cold air. It is denser because the molecules are closer together, absorbing less energy and not moving as much.

The lower density in hot air makes it lighter than cold air, so it rises.

Stay well insulated

Want to learn more about insulation and roofing? Angie's List can help:

Is poor attic ventilation damaging your roof?

How to reduce energy costs with attic insulation.

● Angie's List guide to insulation and weatherstripping.

● Angie's List guide to roofing.

Hot air ends up in your attic

As the hot air rises in your home, it will come in contact with your attic. And if your attic lacks sufficient insulation to keep the warm air inside your home, that warm air will make its way through the attic, through your roof into the outside air.

This means that your heating system must work harder to continue to heat your home. And that causes your energy bill — like hot air — to rise.

Keeping the heat where it belongs

By properly insulating your attic you can keep warm air from escaping. This means your heating system uses less energy, because it's not constantly heating cool air. With proper insulation levels, you save money on your energy bills month after month.

You may have insulation in your home’s walls and attic. But you’ll also want to look at the roof itself. Warm air is very good at finding even the smallest escape hatch, such as missing shingles, poor ventilation, unsealed pipe boots and even nail pops.

Another reason that energy costs may be going through your roof is that heat energy is transferred by conduction through the walls, floor, roof and windows. It’s also transferred from homes by convection. For example, cold air can enter the house through gaps in doors and windows, and convection currents can transfer heat energy in the attic to the roof. Heat energy also leaves the house by radiation through the walls, roof and windows.

Insulation: not just for winter

Insulation isn't just a wintertime solution. Properly insulating your attic can keep your energy costs down year-round, making it difficult for indoor air to escape and for outdoor air to enter. In the summer, that means that less hot air comes in from outdoors and less air escapes from a cool house.

All of this adds up to a more comfortable home and cost savings on energy bills every month of the year.  

A version of this article appears on the ReNew Services Group blog.

As of March 9, 2015, this service provider was highly rated on Angie's List. Ratings are subject to change based on consumer feedback, so check Angie's List for the most up-to-date reviews. The views expressed by this author do not necessarily reflect those of Angie's List.

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