What's the Best Way to Make Your Roof Environmentally Friendly?

What you do with your roof can have a significant effect on the environment and global warming. It can also have an impact on your energy bill and the value of your property. Some of the options include installing solar panels, implementing a roof garden, and using light-colored materials to reflect the sunlight.

Solar Roof

Solar panels help the environment by generating electricity from a clean source and reducing or potentially eliminating your consumption of electricity produced from fossil fuels. By installing a solar photovoltaic system at home you can also save hundreds of dollars a year on your electric bill and increase the market value of your home.

The cost of installing a solar system can be significant and varies depending on where you live, the size and rating of the system, and the installer. But the various types of financial incentives available can reduce your installation cost by half or more in some places. You can claim a federal tax credit; many states offer a state income tax credit; and many utility companies offer financial incentives such as rebates, low-interest loans, and production credits. According to the U.S. Department of Energy, after taking into account the rebates and other incentives, the cost of a 2-kW solar system, which is enough to offset the energy needs of an energy efficient home, ranges from a high of around $16,000 in places like Columbus, Missouri and Concord, New Hampshire, to a low of around $7,000 in Denver, Colorado.

Homebuyers are interested in the environment and saving energy and this is reflected in home values. The U.S. Department of Energy indicates that according to the Appraisal Journal, written by leading practitioners in the real estate appraisal profession, for every dollar that you reduce your annual electric bill by installing a solar system, the value of your home increases by about $20.

Roof Garden

If you have a flat roof, a roof garden can be an environmentally friendly option. A roof garden can be aesthetically appealing by providing a natural oasis among the concrete of an urban area. The plants on a green roof absorb carbon dioxide, release oxygen, and can trap airborne particulates. The natural process of transpiration reduces the air temperature.

Roof gardens absorb rainwater, which reduces runoff. The water is cleaned and filtered as it passes through the soil. The gardens also promote local biodiversity by providing habitats for birds and insects. By planting native species accustomed to your local climate conditions you can reduce the need for watering.

According to David Lemberg in an article for the Alternative Consumer, roof gardens help insulate buildings, keeping them cooler in the summer and warmer in the winter. In the summer, the rooms in a building with a green roof can be 5 to 7 degrees Fahrenheit cooler than the air outside. And in winter, buildings with a roof garden lose 30 percent less heat.

Light Colors

A light colored roof reflects more of the sun's rays, which could help to reduce global warming. Michael Graham Richard, in an article posted on the Treehugger website, points out a study conducted by the Earth Institute at Columbia University indicating that the Earth overall reflects about 29 percent of the sunlight that falls on it. Towns reflect only about 10 percent. Since about 3 percent of the Earth's surface is covered with buildings and pavement, painting all the roofs white could increase the amount of sunlight reflected, and thereby cool the earth.

Mark Clayton, writing for The Christian Science Monitor, quotes Dr. Hashem Akbari, a researcher at the Lawrence Berkeley National Laboratory in California, who said that a 1,000 square foot area of rooftop painted white would have the same impact on global warming as cutting 10 tons of carbon dioxide emissions. According to his calculations, by painting all the world's rooftops and pavement white the effect on global warming would be equivalent to taking all the automobiles in the world off the road for 11 years.

By reflecting more sunlight, a white or at least a lighter-colored roof can reduce the amount of energy needed to cool the home or building during warm weather. So in addition to offsetting the warming effect itself, a light-colored roof helps reduce the consumption of energy and the emission of greenhouse gases that are causing global warming, assuming the energy to cool the home is coming from non-renewable sources.

Another option, in the interest of doing everything possible to help the environment and reduce global warming, would be to use the best combination of measures based on practical and budgetary considerations. Installing as many solar panels as economically feasible, planting a roof garden in available spaces on a flat roof, and covering the rest with white or light-colored materials could be a good solution.

To find out about all the different incentives for renewable energy systems like solar photovoltaic systems and for energy efficiency improvements at home, including roof gardens and light-colored roofs, you can check the Database of State Incentives for Renewables & Efficiency. This database has all the federal, state, and local financial incentives for installing renewable energy systems and for making energy efficiency improvements at your home or business.

Sources:
David Lemberg, "Green Roof Gardens" - The Alternative Consumer
"Financial Incentives for Renewable Energy" - Database of State Incentives for Renewables & Efficiency
Mark Clayton, "How white roofs shine bright green" - The Christian Science Monitor
Michael Graham Richard, "How to Help Prevent Global Warming on Your Roof" - treehugger
"Planning for PV - The Value and Cost of Solar Electricity" - U.S. Department of Energy