Home Performance Meets Green Renovation

A version of this article appears in the November/December 2005 issue of Home Energy Magazine.

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        In 1991, Dennis Creech and his wife,Callie Pendergrast,were looking to expand and renovate their 1950s ranch-style house.They needed additional space for their teen daughter, and they also wanted to update the original kitchen and bath; at the same time, they also knew that, if possible, they should do everything they could to correct problems they had noticed in the house. Moisture had been an issue for years—there was evidence of crawlspace water intrusion; the bathrooms lacked exhaust fans; and mold formed on walls in adjacent rooms. Room temperatures were uneven.
        As executive director of Southface Energy Institute in Atlanta, Creech was well aware of the link between indoor air quality (IAQ) and energy efficiency. At the time Creech and Pendergrast were looking to renovate their ranch house, Southface was piloting Earth- Craft House, a green building program that it had developed jointly with the Greater Atlanta Home Builders Association. Earthcraft House already had plans on the drawing board to develop a renovation component to complement the new home program. The Creech-Pendergrast residence became the test house for the EarthCraft House Renovation program.
        The first step in EarthCraft House Renovation is to assess the house to identify opportunities to improve the home’s performance in areas that can be incorporated into the renovation project. EarthCraft House Renovation focuses on improving home performance as well as lessening the environmental impact of renovation (see “A Greener Career”).To qualify for certification in the program a home must be scored on a worksheet. Points are awarded in the areas of the building envelope,HVAC, ventilation,water, fixtures and finishes, waste management, outdoor projects, and homeowner and contractor education. The larger the scope of the project, the more points are required to achieve certification.While some gut renovations can be treated as virtually a new home, more modest projects do not have the same potential for increasing envelope and duct system tightness. More points are awarded for more substantial improvements in air infiltration and duct leakage reduction. Points are also awarded for conservation alternatives. For instance, points are awarded if the added finished area is conditioned using the original HVAC system—this rewards envelope improvements and duct sealing that improve overall performance.
         An assessment of the Creech-Pendergrast residence confirmed what Creech had suspected.The home was leaky (± 0.8 ACHnat), with a leaky duct system located in the ventilated crawlspace. Correcting these leaks and the moisture and mold problems alone would improve the IAQ, comfort, and efficiency, but incorporating these repairs into a renovation and addition would provide more opportunities to make the project greener (see “Project Score- card—The Creech-Pendergrast Residence”). The project scope included an addition of 960 ft2 of finished space on two levels for a master suite and family room, and a renovation of the existing bath and kitchen.
        The results are pleasing to the eye with comfortable, airy, healthy spaces. Determining the additional costs to make the project greener is difficult, because Creech and Pendergrast included items like dehumidification, air and duct sealing, exhaust fans, and low-VOC paint for their health benefits, regardless of their cost.
        After the renovation, use of electricity decreased—which is notable, given that the house was now significantly bigger. Winter electricity use decreased by 36%.This decrease is due to reduced run time on the furnace electric blower and to the improved thermal envelope. The improved thermal envelope also accounts for a 17% decrease in summer electricity use. The summer reduction is probably not as large due to the use of the dehumidifier, which, while sacrificing some energy conservation, does improve air quality.
                        Improvements to the building envelope included blowing cellulose insulation into exterior walls and ceilings and sealing the crawlspace and basement. These improvements allowed Creech and Pendergrast to use the existing furnace and air conditioner to condition the expanded house, in spite of the fact that they had added almost 1,000 ft2. This saved approximately $5,000, offsetting other costs.The house is more comfortable and mold has been eliminated, resulting in better air quality. Now the owners wouldn’t have it any other way.

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