Skilled Trades

Wasted Attic Heat Being Put to Good Use

Skilled TradesMay 30, 2015

By Gary Lyu, Program Director at Fortis College in Salt Lake City Heat tends to rise into home attics, wasting precious warmth during winter and causing air conditioners to work harder in the summer, leaving homeowners with ever-increasing electric and fuel charges. If only the extraneous heat could be used to lower heating and cooling costs instead of hiking them. Now they can be. At its Fortis Test Home, the HVAC department at Fortis College in Salt Lake City has implemented a process that harnesses residential attic heat to provide free space heating for the rest of the house. Every attic holds wasted heat created by the sun’s rays hitting the roof.  Typically, attic floors are insulated keeping the heat away from residents – good for summer but not optimal in the winter when expensive fuel is burned to heat the home. Attic heat eventually escapes through roof or gable vents and is lost, but at the Fortis Test Home in Salt Lake City, the Fortis College HVAC department has engineered the test house to capture this heat and redirect it into the home, where it can warm residents. As the attic heat rises during the middle of a typical March day, it reaches a point when it is sufficiently high enough to create opportunities for actually heating the home. To redirect the heat, a filtered fresh air duct was installed in the attic’s peak where hot air created by the sun is drawn down into the furnace’s return air system. A special thermostat in the attic activates the circulation fan when the temperature rises above 75 degrees, drawing in heated air and circulating it throughout the home via existing ducts. The process can heat the home from noon until 9 p.m. on clear days and, because the heat is free, owners can let the inside temperature rise higher than with fossil fuels. As a result, the home won’t need conventional heat until the next morning. The Fortis system can reduce fossil fuel usage by 50% on days when the sun is unobstructed. And, when summertime attic temperatures exceed 140 degrees, it is used to heat the home’s hot water supply, reducing that expense to near zero all summer. Smart home technology like this helps control expenses while reducing our carbon footprint through the use of recycled energy. It’s the power of “green” being put into practice by HVAC students at Fortis College in Salt Lake City. If you’d like to learn more about the new, “smarter” HVAC programs offered at Fortis schools, visit