Greening your roof

To determine the best way to green your roof, first think about your roofing needs and what you hope to accomplish. Do you want to generate electricity, control runoff, or just cool things down? Are you replacing an old roof, building a brand new home, or hoping to improve the performance of an existing roof without removing or replacing it? What sort of climate do you live in? Are you more concerned with staying warm in the winter, cool in the summer, or both? And, last but not least, how much are you willing and able to spend? Are you prepared to spend more up-front for potential long-term returns, or do you want to do whatever you can with very limited financial resources?

If you live in a hot climate and your primary objective is to lower your cooling costs, a cool roof is a less expensive alternative to a green roof. A cool roof reduces the surface temperature of your roof, lowering the temperature inside your home. If your roof is currently black or another dark color, consider cooling it off by coating or shingling it in a light color. If you have a flat or barely sloped roof, you can have it recoated in white for 75 cents to $1.50 per square foot [source: Environmental Protection Agency]. If your roof is steep, you can replace your standard shingles with a "cool pigment" shingle for anywhere from 60 cents to $2.10 per square foot [source: Environmental Protection Agency].

If money is no object and reducing your carbon footprint is your top priority, alternative energy technologies such as solar panels and wind turbines can use your roof's exposure to sun and wind to generate some or all of your household electricity. But their high price tag (from around $3,000 for a small 1-kilowatt residential wind turbine to upwards of $33,000 for a solar array to provide all the electricity for an average home) means that it will take years to recoup your initial investment [source: Windustry].

Even if a green roof, cool roof, or solar array isn't in your budget, there are ways to put the surface of your roof to work for you. These super-affordable options won't reduce temperatures on your roof or solve global warming, but they can help you cut your utility bills and reduce your environmental impact. Read on to see if one is right for you!