Bethesda ‘passive house’ uses less energy

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Earth Day can be celebrated in a variety of ways, but being passive is the celebration of choice for Brendan O’Neill Jr., vice president of O’Neill Development Corp. in Gaithersburg, and David Peabody of Peabody Architects in Alexandria.

Mr. O’Neill and Mr. Peabody, along with a team of local subcontractors, are completing the first “passive house” in the Washington area. The passive-house program is a certification program and a design and construction technique that results in a building that uses between 75 percent and 95 percent less energy for heating and cooling than buildings that meet current U.S. codes.

The local passive house, at 4717 N. Chelsea Lane in Bethesda, uses just 10 percent of the heating and cooling energy of a standard house. The home, built in traditional American “foursquare” style, has five bedrooms and 4½ baths in about 4,300 finished square feet, including a basement, main level and second and third floors. The projected annual total energy cost for this home is just $850, or about $70 per month. The home will be on the market within a few weeks, listed at about $1,680,000.

“Basically we built our passive house on the shoulders of other people,” Mr. Peabody says. “The process began with the superinsulated houses that were built in the 1970s in response to the energy crisis. Those houses had problems with moisture and ventilation, which have been addressed by designers of passive houses.”

Mr. Peabody says more than 20,000 passive house projects have been built in Germany, which recently adopted passive-house standards as the energy standard for all new construction. The passive-house system has been used for schools and high-rise office buildings as well as homes.

“In the U.S., there are about 20 passive houses, but ours is the first to be built in the Washington area,” Mr. O’Neill says.

The first passive house in the U.S. was built in 2003 in Illinois. When Mr. O’Neill and his father, Brendan O’Neill Sr., visited the Illinois house, they immediately were intrigued by the program because the home was both silent and warm in the midst of a blizzard.

“The main thing that is different about a passive house compared with other green buildings is that the focus is solely on using less energy,” Mr. O’Neill says. “We built this house so you can add solar thermals for water heating and other items that I call ‘green bling’ later, but right now it uses less energy overall and has good air quality.”

The appliances in the Bethesda passive house are all Energy Star and the water heater is a gas-fired tank with a solar heat exchanger that is prepared for a future solar hot water system. The windows are triple-glazed and motorized awnings shade and protect the home’s west wall and front porch overhangs protect the south wall.

The passive house has no need for a traditional furnace, but in the Washington area’s climate with its cold winters and hot, humid summers, the residence does need a dehumidifier and a very small air-conditioning unit for the summer. A small, high-efficiency heat pump provides supplemental heat if it’s needed during the winter.

“The passive house relies on an energy recovery ventilator system, which essentially acts like a big fan to bring in air from the outside and exhaust air from the inside,” Mr. Peabody says. “The ventilation system also makes this a healthy house, since it operates constantly, exhausting stale air from the kitchen, bathrooms and laundry and replenishing it with fresh air from the outside.”

Mr. O’Neill says the passive house does not have any drafts because of the extreme level of insulation, so the temperature is consistent within 1 degree throughout all four levels.

“The temperature is regulated because the outside air passes over a geothermal loop built into the soil surrounding the house, which heats it during the winter before it comes into the house,” Mr. O’Neill says. “In the summer, the opposite happens, with the air cooling down as it crosses over the geothermal loops and travels within the ventilation system inside the house.”

When homeowners want fresh air, they still can open the windows and doors without having an impact on the ventilation system. The home has windows that resemble double-hung windows but are actually casement windows, which are more energy-efficient.

The amount of insulation in the passive house keeps the warmer or cooler air contained within the house rather than allowing it to leak out through the joints and windows.

“This house has insulation under the footers and under the slab,” Mr. O’Neill says. “A critical element was making sure that all the joints were sealed tightly and that the home was built without any spaces where air infiltration could occur.”

The builder added an energy-use monitor to make sure the system works in all temperatures.

“The home cost about 6 [percent] to 8 percent more to build as a passive house compared to a conventional home of the same size and design,” Mr. O’Neill says. “We would expect that the cost should be a little lower on future passive-house projects because as this program becomes more popular, there should be a greater availability of the products needed to build them.

“Our labor costs will probably decrease, too, as we get more familiar with the building technique.”

While Mr. Peabody and Mr. O’Neill deliberately designed the Bethesda home as a traditional foursquare, a passive house can be built in any architectural style.

“We are starting work on a much smaller, 1,200-square-foot passive house next, but you can really do whatever you want as long as you can crunch the numbers to make it economically feasible,” Mr. O’Neill says. “The inside of the house doesn’t really matter at all, it is just the building envelope that counts”

Mr. Peabody says the passive house program is particularly valuable for affordable housing developments because lowering utility bills can be even more important for low- or moderate-income households. The passive-house program can be used to retrofit existing single-family homes and multi-unit buildings.

For more information about the North Chelsea Lane passive house, contact Realtor Sondra Mulheron, with Long & Foster Real Estate in Potomac at 301/785-9536; visit www.oneilldev.com or www.greenhaus.org.

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