Light-colored materials reflect heat, but dark roofs, such as asphalt or tar, absorb heat, increasing air-conditioning use to compensate. In other words, building a white or "reflective" roof helps save energy and money. The color of a roof also affects its durability: darker colors tend to be less durable, while whites are more likely to peel off in large sheets when it's time for replacement. Reflectivity is the key word here. A highly reflective roof will reflect much of the sunlight that hits it back into space, reducing your house's heating costs and preventing your roof from aging prematurely. White roofs are the most reflective, with aluminum being second most reflective and black being the least reflective. The best time to replace your roof is before significant damage occurs. If you notice any leaks or tears in the material, get them repaired by a professional before they become larger problems. Roofs last between 10 and 20 years depending on how they are maintained; if you care for your roof by removing any debris or old shingles and washing away any water spots with a gentle detergent and warm water, it will help preserve the life of your roof. Contact your local utility company to see if they offer any incentives for installing solar panels or energy-efficient appliances. Some companies may provide special rates or discounts for those who commit to green energy practices.