Ventilate your roof to help cool your home in the summer and prevent ice dams in the winter. Do this by installing intake vents and a solar-powered fan (you may need two, depending on your roof size) that draw out warm air trapped in the attic.
Cost: Systems start at $250.
Savings: In Texas, for instance, where the average annual cost to operate a central-air unit is $668, fan makers claim you can save 30 percent on your operating costs, or $200 per year.
Bonus: You may be eligible for federal and/or state tax rebates to help cover the cost of your setup.