Therma-Hexx markets the panels for a variety of uses, including heating sidewalks and driveways during the winter to clear surfaces of snow and ice, cooling the surface of patio pavers by collecting heat, and using solar energy to heat pool water. The panels, manufactured from two types of polyethylene plastic, are roughly 2-feet square and 1.4 inches thick and are installed immediately below the paved surface. Flow rates of liquid through the panels can range from 0.25 to 1.25 gallons per minute, with a heat exchange rate of up to 500 Btu per hour. The panels can be recycled. The company typically sells the panels as part of an engineered system, not individually, and says pricing depends on the specs of the job.

Therma-Hexx, 603/319-8815,