Wasting energy at home costs money and increases pollution. Shahed Mustafa, an engineer with a master's degree from the University of North Texas, teaches Cedar Valley College students how to audit homes' energy use. He offers these tips:

• Get a home energy audit. An audit can spot places where air that you're paying to heat in winter or cool in summer is escaping. Ask your retail energy supplier about free or low-cost audits, or check the Web for energy audit services in your community.

• Pay attention to leaks from ducts. These can be hard to find, but they waste money and energy.

• Tightening a house against air leaks can prevent the release of fumes, dust and chemicals from everyday life, worsening indoor air quality. Compensate with a highly efficient air filter with a rating of MERV-12 or higher – that's its minimum efficiency reporting value, set by the American Society of Heating, Refrigerating and Air-Conditioning Engineers.

Filters with higher numbers can catch smaller contaminant particles and keep the air cleaner. Avoid the cheapest filters; they may have only a MERV-1 rating, meaning they fail to block many contaminants.