We also recommend Cool Roofs
These roofs use material with high solar reflectance and thermal emittance, reducing the temperature of the roof, and therefore your home, on hot sunny days. This will also save you money on air conditioning costs since less heat is coming in through your roof. Click here for the Cool Roof Rating Council’s product directory for manufacturers and styles available that meet this standard. To further reduce energy costs, you may want to consider Solar Systems and White Roof Coating. If you have an existing flat roof, adding White Roof Coating makes it instantly more energy efficient.