Question
Which is better for energy saving: a white or a dark roof?
I think a dark roof gets more heat than a white roof due to radiation. But most of the roofs in my area are dark. I live in San Antonio.
Answer
Considering your location and region, you have a greater number of cooling days vs. heating days. To reduce solar heat gain and reduce energy costs during the cooling season, a white roof or a light roof color would be best suited.
But do not only go by color.
Most roofing manufacturers will list the Solar Reflective Index (SRI) for their products. This number is associated with the amount of heat gain experienced by that specific material and color.
Look for a high SRI number. The higher the SRI number, the greater the solar reflectance, the less heat gain, and the less energy used to cool your home.