Your roof is a major source of heat in your home, and if you have a poorly insulated roof or use inefficient materials, your home could be absorbing much more heat than you want it to. If you aren't choosing a roof for a house still in construction, it can be expensive to modify a currently installed roof, though the savings can quickly add up. What exactly you can do to your roof depends primarily on the temperature and climate of the area you live in.
Roof Material Ratings
If you haven't looked at roof materials in a while, there are a few things you want to look out for.
The first is the material's SRI (solar reflective index). This is a measure of how well the material reflects heat away from your home instead of absorbing it. This is often determined by color (light colors reflect light better), but can also be determined by the type of coating put on the material.
The second is the material's thermal emittance. This measures how much absorbed heat radiates back into the environment rather than warming your house.
Many roofing materials have a high thermal emittance rating, so the big factor in your decision will probably be the SRI.
If you live in areas with consistently high heat, you want a higher SRI to reflect most of the heat away. If you live in cooler areas, however, a roof that absorbs more heat can save you money when it comes time to use the heater.
Choosing a Roof Material
If efficiency is your primary goal, you may end up choosing something different than you had originally imagined for your roof. Roof materials range from metal and tile to asphalt shingle and polyurethane foam. You will be limited slightly by the weather where you live, and after that, you should decide based on the longevity of the material and how well it will improve your roof's efficiency.
For example, if you live in an area that occasionally gets hail, you may not be able to use roof tiles; hail can shatter them, requiring frequent and costly repairs. You can use an alternative like metal (such as steel and aluminum), which may not be the most attractive material, but which rates very highly for reflectivity.
A roofing contractor will be able to give you specifics on what you can use in your area, so don't be afraid to consult professional help.
Reinsulating Your Attic
If you don't want to buy all-new materials, you can still heavily improve your roof's efficiency. Insulating your attic can prevent as much heat from being absorbed into your home; look at insulation with high R-value, which measures resistance to the transfer of heat. For a quality job you should still hire a professional to do the work, but you can do the legwork for the materials on your own.
Installing Solar Panels
If you've been thinking about installing solar panels, this is also a good way to reduce how much heat hits your roof. Much of the heat will be absorbed by the panels, not your roof, and since solar panels are slightly elevated, not much heat will be transferred to the roof itself. With solar panels, not only are you decreasing the heat that is absorbed into your roof, you're also generating a lot of your own power.
Adding a Coating
You can sometimes add a reflective coating to an existing roof that will improve its reflectivity and thermal emittance rating. You can buy coatings at many hardware stores, though you may want a contractor to apply it. Make sure you use a coating instead of new paint; using a lighter-colored paint has little to no effect.
To learn more, contact a roofing contractor like Emerald Roofing.