Next week, Adrian and Eric Humphreys will move into a new house in Columbia, Md., that looks from the outside just like nearby houses. But it's different.
Every 15 minutes for the next two years, the Humphreys' energy usage will be monitored by sensors throughout the house and transmitted to Baltimore computer that will analyze the data.
Through the combined efforts of Baltimore Gas and Electric Co., the Takoma Park architectural firm of Price & Partners and Columbia Builders Inc., the house has undergone relatively low-cost modifications that have converted it to a passive solar heating and cooling system.
The project is believed to be the first such conversion of a tract house.
The changes made to the house include:
* Alteration of the window arrangement. The amount window surface facing north was reduced 27 percent, and windows on the western side of the house were eliminated. The number and size of windows with southern exposure were significantly increased; the glass surface facing south was more than doubled from 63 square feet to 168 square feet.
* Installation of special shades, called "movable" insulation. The linen-look fabric shades are made of reflective aluminized Mylar and move on an airtight track with magnetic seals. Electronic sensors at the base of each shade will monitor their effectiveness.
* Addition of a tile floor on the first-floor room facing south. The 26-by-12-foot combined living and dining room has a masonry tile floor to hold the winter sun's heat.
Extension and addition of roof overhangs on the south side of the house's exterior to provide more protection from the summer sun.
* The doubling of the insulation along the perimeter at the base of the house to eliminate loss of stored heat.
These changes cost between $2,000 and $3,000 and are intended to pay for themselves in lower energy bills within six years. "The changes will provide a 35 percent annual energy savings over the regular house," architect Travis L. Price III said.
The idea originated with Baltimore Gas & Electric, which has spent about $30,000 on computer equipment for the project. "We want to find some means to help customers conserve energy and maintain a comfortable life style that's affordable," said BG&E senior engineer Robert A. Diehl.
The utility turned to passive solar after deciding active solar wasn't cost-effective, Diehl said. A passive solar system is one in which the thermal energy flows by natural means.
"There is nothing mechanical to break down in a passive solar system," notes Richard Bishop, co-owner of Columbia Builders.
Diehl employed architect Price, who's been doing solar work exclusively for the last dozen years, to redesign a home using passive solar devices thatwill work in this climate at a price the average homeowner can afford.
"We do a lot of custom solar work, but it was becoming clear over the last few years that you have to get passive solar to builders who are getting to the people to have a major impact," Price said. Both he and BG&E weren't interested in the people who have $10,000 or more to spend on solar devices for expensive houses, he said.
Then Diehl and Price sought a builder who could make the modifications for about $2,000 on a house that would sell for under $90,000, exclusive of its lot. They were also insistent that the solar design modifications pay for themselves within six years and that the house qualify for a National Energy Watch Award, which goes to homes that meet certain energy-conservation standards under a program sponsored by the Edison Electric Institute.
Columbia Builders was able to make the modifications easily, according to Jim Greenfield, co-owner of the Columbia-based firm, since it routinely customizes its standard homes to meet customers' demands.
According to Price, the purpose of the modificiations was to open the house up to the south. "That's really our solar machine," he said. Another key in this latitute is the solar angle. The roof overhangs let the house shade itself, Price noted. Because of the movement of the sun, the south side of the house will be bathed in sunlight on a December afternoon but will be in the shade--thanks to the overhangs--on a June afternoon, he explained.
A total of 34 sensors will monitor energy use in the house. Each appliance in the house has a separate meter to test how much heat it adds to the living space and how much energy it uses. Sensors buried in the tile floor and along the walls will monitor room temperature and humidity. Outdoor sensors will measure the sunshine, and the wind's direction and velocity. The amount of energy consumed by the heat pump and auxilliary electric heat will also be monitored.
"We're not attempting to alter their life style," says Greenfield. The only thing being asked of the house's residents is to open and close the insulating shades, Diehl said.
"We want the shades pulled down when it's a cold day," he said. It's an experiment; if people don't like living with the shades down, transparent shades may have to be developed, he noted.
The Humprheys are looking forward to living in the house. "The opportunity arose, and we just went with it," said Adrian Humprheys. "It's going to be interesting--being monitored," she said.