Homes look great on paper, but in reality, insulation and HVAC equipment are so poorly installed, the improvements rarely live up to their labeled ratings. Consider these studies about home energy performance:
- A 1998 Washington, D.C.-based U.S. Department of Energy study found 1,500-square-foot homes can have 181 square inches of leakage area. That’s like having a 15- by 12-inch window open all day long every day.
- Measured values from more than 10,000 “CheckMe” reports of residential HVAC installations show 60 percent of air-conditioning systems have excessive or inadequate amounts of refrigerant. CheckMe reports are generated by a certified CheckMe air-conditioning technician who visits the home, takes measurements, then uses a software program developed by Proctor Engineering Corp., San Rafael, Calif., to get results. The refrigerant issue along with other measured shortcomings, like disconnected or restricted ductwork, wastes about 45 percent of installed cooling capacity in thousands of homes.
- Measured values from 60 California homes taken by the Davis Energy Group, Davis, Calif., in 2007 showed that 83 percent of systems failed to deliver the amount of supply air needed to meet the peak loads of the homes. Discomfort and energy waste come from such poorly designed and installed systems because expensive conditioned air does not reach the occupied space. It’s not uncommon to see ducts leak 25 percent of conditioned air to the outdoors, which means 25 percent of the money homeowners spend goes to heating and cooling the outdoors.
- Measured values taken in 2009 and 2010 from 80 homes completed in 2007 show that 80 percent of supply air grilles deliver air too slowly to mix in the space well enough to keep it comfortable. Thermal discomfort makes the homeowner adjust the thermostat, making the system run longer than otherwise would be necessary to heat and cool each space. Excess run-time costs money and wastes energy.
Combining the results of field measurements from those four studies, it becomes apparent only about 3.5 percent of typical tract or custom homes have the correct supply airflow, delivered at the correct velocity. Said another way, 96.5 percent of the homes tested have HVAC systems that don’t work to even the most minimal standards of efficiency.
A 1998 study from Oak Ridge National Laboratory, Oak Ridge, Tenn., found poorly installed insulation that has voids, gaps, cracks or was poorly lofted (not compressed yet fully fills the cavity) resulted in an energy loss of 28 percent compared to its labeled R-value.
Typical Energy-saving Measures
By using a blower door and an infrared camera, the home-performance contractor locates leaks and thermal passes and air seals them. Most of the focus is on attic and crawl spaces because these are the easiest and most cost-effective to fix. Insulation is upgraded where needed. Depending on air-tightness levels, fresh air ventilation is often provided.
A detailed HVAC analysis is done to determine proper airflow and refrigerant charge and if the size of the system and ducts matches the true needs of the home. Sometimes the entire system is replaced. If not, the system is sealed, repaired and tested to work correctly. Airflow is properly adjusted for each room.
Water-heating costs often can be nearly as much as heating and cooling costs, so water heaters are replaced with high-efficiency direct vent gas water heaters or heat-pump electric water heaters.
If the home’s windows need to be replaced because of leaks, wear and tear, high-performance low-E windows are installed. The cost difference between a standard double-glazed window and a very energy-efficient low-E product with argon gas is only about $1 per square foot.