Three engineers from Steven Winter Associates, a Norwalk-based environmental consulting firm, were erecting a peculiar-looking device in one of the front doors of a new duplex at 128-130 Holly St. in Bridgeport, on the morning of Nov. 22.
The machine, which consisted of a high-powered fan set in a metal and plastic frame hooked up to an electronic pressure-measurement device called a manometer, is the main piece of equipment for what is called the blower door test.
“What they test for is how much air is leaving the unit,” said Elizabeth Torres, executive director of the Bridgeport Neighborhood Trust, which built the house.
The 2,300-square-foot house — which boasts recycled vinyl siding, spray foam insulation, argon windows, recycled exterior doors, low-flow plumbing and sustainable landscaping — is an experiment in green building by the Bridgeport Neighborhood Trust, a nonprofit dedicated to affordable housing.
The blower door test, Torres explained, is one of the tests that will determine the LEED status of the new house.
LEED, which stands for Leadership in Energy and Environmental Design, is a certification system developed by the U.S. Green Building Council (USGBC) to rate the design, construction and operation of buildings. LEED-rated buildings may fall into one of four tiers: platinum, gold, silver, or bronze.
Before the blower door is turned on, all the ducts are taped over, all the interior doors are opened and all the exterior doors are closed.
When the blower door is turned on, the air pressure in the house drops. Air rushes in through small openings, like electrical sockets and light switches. But the house itself appears to be sound.
Matthew Slattery of Stephen Winter Associates and his colleagues peered at the manometer, but discovered that although the house appears to be getting a good readout, they will have to return to test the unit — the furnace and hot water heater are not yet installed.
According to Torres, the Holly Street home is the first project in the state to combine the ideals of building green with the ideals of affordable housing. It is unlikely to be the last such project, she said.
“We intend to continue to do this,” said Torres.
In fact, she said, the Bridgeport Neighborhood Trust is planning to build a nearly identical house across the street, in a currently vacant lot.
“We have to sell this one first,” she said.
The second home, said Torres, will be a prefabricated, modular construction, while the first home was built with stick construction, framed and built from the ground up. The aim is to bring down the cost of construction.
The first house, which was financed by grants, as well state and city funds, cost $500,000 to build. The unit will be sold for $225,000.
The 26-year-old nonprofit first began working on the concept of green affordable homes in 2005, said Stephen Grathwol, a member of the Southwestern Connecticut Green Building Council, who has been a supporter of the project.
The Yale Urban Design Workshop created the model for the house at Holly Street in 2006. The two lots were secured in 2007. Construction, however, did not begin until the state and the city agreed to help fund the project in 2010.
The project has had its setbacks. Last year the house was broken into twice and copper pipe was stolen.
According to the Bridgeport Neighborhood Trust’s site, interested homebuyers must enter a lottery to be eligible to purchase the home. To enter the lottery, the potential buyer’s household income must not exceed 80 percent of Bridgeport’s median income, so, for example, the income of a family of five can be no more than $69,350 to purchase a three-bedroom home.
There are some other restrictions as well. The purchaser must intend to live in the property, must be a first-time homebuyer, must be pre-approved for a mortgage and must complete a homebuyer education counseling program. The owners are also unable to resell the property until 15 years have passed.
Although the family that buys the house must live in it, the Holly Street homes will provide an opportunity for the buyers to collect rental income. Both homes contain two units, which can either be combined to house a large family, or kept separate so that there is a main unit and a second rental unit.
Torres hopes that the Holly Street project will show other communities that building green and affordable housing projects don’t have to be mutually exclusive.
“It’s not as hard as it may seem,” she said. “Once you learn about it, it’s much easier.”
According to Slattery, the unit at 128 Holly St. was retested on Dec. 16, and attained a final blower door reading of 850 CFM50 (Cubic Feet per Minute at 50 Pascals of pressure).
“This roughly correlates to about 20 percent of the volume of air in the house leaving every hour due to natural leakage,” he said in an email. “Generally, anything less than 30 percent is considered very tight.”
The other unit, 130 Holly St., tested at 940 cubic feet per minute, which equates to about 25 percent of air leaving the house an hour.
Slattery also conducted a duct blaster test, which measures the leaks in the duct system.
He does not yet know whether the house will be LEED-certified platinum, gold, silver or bronze.
“We have not gathered all the documentation needed for LEED, so we still don’t know what tier will be achieved,” he wrote. “The results of the energy test are certainly positive, and will have a significant effect on the LEED score, but because LEED accounts for so many facets of green building, it’s difficult to say whether the results will move the project into a higher tier.”
Torres said that Bridgeport Neighborhood Trust is still seeking a buyer for the home.