Q. I can feel a lot of heat radiating down from the bedroom ceiling under the attic. It actually feels warm to the touch. Will those turbine types of attic vents help much and what makes the turbine spin? — T.T.

A. Turbine attic vents can be extremely effective and energy efficient because they use no electricity. The wind blowing past the turbine causes it to spin.

By properly ventilating your attic, you can lower its peak temperature by 40 to 50 degrees. This not only lowers your air-conditioning costs and makes you more comfortable, but is increases the life of the roofing materials and structural lumber in your attic.

A great advantage of turbine vents is that they spin with the wind blowing from any direction. This is important because the prevailing wind direction changes from spring through fall and from day to day. Gable vents are ineffective when the wind blows from the front of your house.

The centrifugal action of the spinning turbine blades creates a nimbus of low pressure in its center. This low pressure area, along with the natural tendency of hot air to rise, draws the hot air out of your attic.

You should locate the turbine vents (you will generally need more than one) as near as possible to the peak of your roof. This allows them to catch the wind from all directions without interference from the roof. The attic air is also hottest at the roof peak. It is also important to space them properly along the roof for effective ventilation.

Turbine vents are generally available in 12-inch and 14-inch diameter sizes. For a 1,500 square foot attic, you will need two 14-inch turbine vents. This provides the recommended 1 to 2 cubic feet per minute of air flow for each square foot of attic floor area.

You will also need about five square feet of net free vent inlet area. The ideal location for the inlet vents is in the soffits under the roof overhang.

You can write to me for Utility Bills Update 90 showing a chart of recommended sizes and spacing of turbine vents and inlet vent areas for various-sized attics and a list of suppliers of the new flat ridge vents. Please include $1 and a self-addressed business-sized envelope. Send to James Dulley, 6906 Royalgreen Drive, Cincinnati, Ohio, 45244.

Q. I plan to add rigid foam insulation to my living room walls when I remodel. I want to use a type that does not contain chlorofluorocarbons that hurt the ozone layer. Are there any type made? — H.L.

A. Chlorofluorocarbons (CFC’s) are suspected of contributing to the destruction of the Earth’s ozone layer. This has very serious long-term health consequences for people, animals, and plants.

Polystyrene rigid foam insulation board does not use CFC’s as the foaming agent in its production. Generally pentane and a flame modifying agent are used.

James Dulley studied energy management at the doctoral level at Harvard.