Energy efficiency tax incentives are available at the federal and the state level for things like replacing doors and windows, installing new energy-efficient heating and air conditioning systems. In my state, our power company offers incentives for retro-fitting existing buildings. The following is from their web site: 'Earn incentives up to $100,000 per site, per year for qualifying energy-saving improvements to commercial or industrial buildings. Eligible projects cover lighting, air conditioning systems, plug loads and more.' This is not a tax incentive, but an actual rebate of project costs. Projects must be pre-approved and they must be completed within 90 days of approval.