SmartAir Graph (IMAGE) University of Utah Caption This graph shows that when a home heating and air conditioning system turns on and off based on temperature alone (Normal), the air quality in the home can result in the dirtiest air based on 2.5 particulate matter. Meanwhile leaving the heating and air conditioning on all the time (On) results in the cleanest air at the expense of using the most energy. The SmartAir plot shows that a system that turns on and off based on both temperature and air quality can result in a home with much cleaner air but without a much higher cost in energy. Credit University of Utah/Neal Patwari Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.