Home energy improvements can have consequences

Residents need to find out how changes will impact the safety and durability of their homes.

With an influx of federal stimulus funding aimed at increasing energy efficiency of homes, University of Minnesota building scientist Pat Huelman expects to see more people making modifications. And though the extra money isnâÄôt a bad thing, as it could help in reducing the 20 percent of U.S. energy use accounted for by residential buildings, it has him worried. Houses are complicated, interactive systems âÄî Huelman likens them to vehicles âÄî and they react to changes, like additional insulation or window replacements, in ways the average resident might not expect. He and other building scientists want to make sure people âÄî especially those developing green building programs âÄî understand the web of connections between the components of a house, like roofing, insulation, appliances and heating systems, and the way changes impact its energy efficiency, safety and durability. For example, adding insulation to attic areas can create moisture problems if warm air from the rest of the house is still leaking into the space. That air transports water-vapor, funneling moisture into the now-colder attic, possibly causing mold or wood deterioration. Funding from FebruaryâÄôs stimulus bill has increased the tax rebate residents can receive for making energy-efficient home improvements, such as adding insulation and replacing water heaters, windows and doors. Phil Smith , an energy specialist at the Minnesota Office of Energy Security , expects to see more people make changes to their homes. But only a small percentage of people appreciate the interaction of the building as a system, Smith said. Misguided modifications can endanger health and compromise a homeâÄôs durability, he said. A group of University students learned that firsthand in their energy efficiency work on a low-income St. Paul residence. The homeowner had requested her attic be converted into a livable space, and mechanical engineering junior Chuck OâÄôNeil , one of the students leading the project, said they were surprised to learn about the way the rest of the house could be affected by attic insulation. âÄúI had no idea,âÄù mechanical engineering and dance sophomore Lauren Butler said. âÄúWe thought we were going to be doing a good thing by sealing up the house. We wanted to make it as airtight as possible to make it energy efficient.âÄù It turns out the houseâÄôs gas stove is already causing carbon monoxide problems, and sealing the house further without improving ventilation would amplify the problem. So the group will still insulate and vent the attic, but will also recommend adding ventilation for the stove and basement water heater. There are several instances where one change may require others, Smith said. For example, a furnace replacement can make it more likely that exhaust âÄî including carbon monoxide âÄî from the water heater will draft back into the house if the water-heater exhaust mode isnâÄôt adjusted. As more people seek these improvements, Jimmie Sparks , energy audit program manager for the Neighborhood Energy Connection , said he anticipates a bottleneck in the number of contractors familiar with making those types of changes. But he said he doesnâÄôt expect a huge increase in demand for energy auditors. SparksâÄôs organization does work for people seeking utility company rebates for energy efficient improvements, which require energy audits. But the federal tax credits donâÄôt require those audits, and Sparks said he doesnâÄôt expect many people to go out of their way get one. But Sparks said anyone wanting to make a change should get an audit. âÄú[We can] help them with that road map of what really needs to be done,âÄù he said. Along with increased tax incentives, the federal stimulus bill resulted in nearly $132 million for MinnesotaâÄôs low-income weatherization program . The Department of Energy , which funds the program, is asking the state to spend 75 percent of that by September 2010, program supervisor Marilou Cheple said. That means next year, theyâÄôll likely weatherize nearly three times the houses they did this year, which was approximately 11,000. Huelman called the program a model for saving energy without compromising safety, air quality or durability, but wondered how theyâÄôll maintain quality as it grows with an influx of funding. Cheple said they havenâÄôt relaxed any of their weatherizing guidelines, and sheâÄôs not concerned about being able to find enough energy auditors. The programâÄôs 32 contract agencies have already hired many of the energy auditors theyâÄôll need, she said, and more are being trained.