Energy tax credit for 2013.
The credit is 10% of the cost of the building materials (labor excluded) for insulation, exterior windows and doors that meet Energy Star requirements, and roofs (metal roofs with pigmented coating, or asphalt roofs with cooling granules). So, if the cost is $5,000.00, you get the full $500.00 credit, except for windows, which have a sublimit of $200.00.
A tax credit reduces your tax bill dollar for dollar, so you're basically getting $500.00 towards your remodel of $5,000.00 or more courtesy of Uncle Sam. You claim it on Form 5695 when you file your tax return.