Have an Energy Assessment done with your home inspection and have an accurate estimate for home energy bills before you purchase.

Decrease the carbon footprint your home leaves with an energy assessment on your house.

The energy assessment was developed by the Department of Energy to show people steps they can take to lower their energy consumption. 
The assessment compares the energy consumption of your house to similar houses in your area, and rates your house on a scale of 1-10 for energy efficiency; from data gathered by the Department of Energy. The assessment then makes recommendations on ways to improve energy consumption. The report then tells where the house rates, on the same scale, once improvements have been completed.
Some of the benifits of the energy assessment program is that it will give the buyer an accurate annual cost they will pay for energy. It gives an estimated price for the improvements and gives you the estimated pay back time.