Performance Tests Bring Comfort & Code Compliance

Performance tester Scott Johnson assembles his equipment and examines the floor plan of a model home before beginning a diagnostic routine. California builders turn to consultants like Johnson to make sure their homes perform well, meeting Title 24 requirements at the same time.

Johnson uses an infrared thermometer to measure air temperature at a supply grille in order to calculate sensible delivery.

New Title 24 standards came into effect in July 1999 (see "California Building Codes Change," HE May/June '99, p. 9). They allow builders to, for example, test duct systems as part of other measures required to meet code. This gives builders some flexibility in offsetting other measures; for example, they may be able to put in larger windows or less insulation. The benefit of performance testing in conjunction with these steps is that it shows the builder how the home systems will perform together after construction.

According to Energy Consultant Bill Lilly, this can work to great advantage in California's hot Central Valley, where a building boom has seen large numbers of new homes going up in the past few years. On some houses, Lilly says, "homeowners had moved in but were not happy, and the mechanical contractor could not fix the problems."

"These homeowners had valid complaints," says Lilly. "The duct systems were not distributing air properly through the A/C systems." Problems in such homes included leaky ductwork and inadequate chases for allowing air flow--especially in some two-story homes. "The mechanical contractor needs more chases to put in enough ductwork, but it is difficult for the builder to provide these after construction is complete. It should be done at the design stage, when it is much more cost-effective," Lilly says.

Lilly's solution is to work with his clients early on to do home performance modeling and measurements. He does computer modeling during planning and demonstrates that the homes must be designed with more space for the duct systems. When performance testing is done during construction, it verifies that the modeling was correct. "Everybody wins," Lilly says, "because--as long as you do an air-flow test with the DuctBlaster--they know what to expect and they have documentation that protects them. People get upset over comfort issues, but how do you measure comfort? With performance testing."

This experience is echoed by Scott Johnson of National Comfort Services, a performance testing company affiliated with the National Comfort Institute. Johnson was called in on a home that smoked up when the HVAC system was turned on, due to backdrafting from the fireplace. He found 545 CFM total leakage from the A/C duct system. Johnson sealed up the supply side of the duct system to put the home back into neutral pressure. After this situation, Johnson says, the builder (who Johnson declined to name because of pending litigation) decided to do duct testing on three new tract home developments, and is taking steps to do performance testing on future projects. "[Performance testing] is going to be taking off very quickly," Johnson says. "By the end of the year, this is going to have a huge impact here in Southern California."

Another builder--Bright Homes, in Modesto, California--has also recently decided to performance-test the mechanical systems in its homes. Dean Jenson, Bright's purchasing manager, says, "This is the only way I know of to assure ourselves and the homeowner that we have the proper design, ductwork, and installation."

--Colleen Turrell

Colleen Turrell is associate editor of Home Energy.

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