If you made your home more energy efficient in 2011, you may be eligible for a non-refundable personal tax credit. Improvements such as insulation, energy exterior doors and windows, water heaters, furnaces and air conditioners can be worth up to $500, of which only $200 may be used for windows. The home must be an existing home and your main residence. Use Form 5695, Residential Energy Credits, to claim this tax credit. This credit is cumulative so if you have used this credit in the last few years, you will only be able to claim what is left over.