If you are looking for energy efficiency and extra comfort in air conditioning, try a system with two-stage cooling. Two-stage cooling allows the air-conditioner's compressor to run at high or low levels. High is the blast of cold air you need on very hot days. Low works fine for milder days.
Your AC likely will run on the low setting most days, saving energy and yielding greater savings than standard compressors. As more Americans move to year-round central air, two-stage cooling offers choice in comfort.