Energy efficiency upgrades, like high-efficiency heating and cooling systems, high-efficiency water heaters, adding insulation and updating your windows, qualify for the 2011 federal income tax credit. If you owe money on your taxes, you can receive a credit equal to 10 percent of the cost of improvements, up to $500. All ENERGY STAR windows qualify, but the most you can receive for upgrading your windows is $200.

If you are considering updating ENERGY STAR windows, you could also benefit from other improvements to your home's envelope, such as, air sealing and adding insulation. In Douglas County, CO, you may be able to take advantage of various rebate programs for home envelope (the exterior of your home) improvements.

Black Hills Energy offers home envelope rebates equal to 70 percent of the cost of ceiling, wall and foundation insulation, up to $2,250. To be eligible, you must first have a free residential energy audit and then install insulation and other envelope measures based upon the recommendations of the audit.

Xcel Energy also offers rebates for home envelope improvements through their Home Performance program. To be eligible, you are required to have an energy audit costing $90 to $120, depending on the services you'd prefer, and a participating contractor must install the recommended improvements. The following measures are required: air sealing, attic insulation and high-efficiency lighting, and rebates total $540 for these improvements. If you complete the required measures you can receive additional rebates on other measures, such as $650 for wall insulation.