White Roofing

The Greek island of Santorini in the Mediterranean is famous for the limestone whitewashed houses that reflect the sun's scorching heat. This is not only nice to look at but also means less energy is needed to cool the buildings.
According to a study from Lawrence Berkeley National Laboratory in California, replacing non-reflective, dark roofing materials with a white roof on a house with a 1,000-square-foot roof would reduce CO2 emissions by 10 metric tons a year.
To put this into perspective, about one metric ton of CO2 is produced from the monthly energy demand of a typical American household.

Vertical Farming

Food production is one of the main reasons for deforestation. Since we need space for agriculture and a healthy climate why don’t we combine both?
Dr. Dickson Despommier of Columbia University has developed a concept that would save trees and energy. Vertical farms, multiple-story greenhouses, produce food right within in the city and cut energy usage; a green roof saves energy in winter because you don’t have heat escaping from the building, and also in summer because it traps cool air inside.