Make your house a BeGreen Home, and receive a window cling with every purchase. Supports cleaner energy sources like wind, solar and biomass through the purchase of renewable energy credits (RECs) Each BeGreen Home represents the following amount of cleaner energy, and offsets an equivalent amount of carbon dioxide emissions based on size: Small Home: 6 Megawatt-hours,or about 4 metric tons of CO2, Medium Home: 12 Megawatt-hours or about 8 metric tons of CO2, Large Home: 24 Megawatt-hours, or about 15 metric tons of CO2.