Three certified passive houses in Boston were built to offer clean inside air, reduced emissions and little to no energy costs.

"It was the open, modern style of the house in West Roxbury, Mass., that first got one couple's attention: a box made of clear-finished white cedar siding that seemed to float above a dark metal base, with large windows, panels of wood slats and high ceilings.

But the main reason they paid $1.4 million for the 2,500-square-foot home was the technology.

"This winter it got freezing, and we were in our shorts," says Amod Athavale, 37, who moved into the newly built house with his wife, Manasi Datar, 36, in July 2022. This summer, the house has remained at 72 to 75 degrees with only a few hours of air conditioning each day, despite the triple-digit heat that hit the city. In fact, their electricity bill currently has a negative balance of about $1,000, meaning the electric company owes them, Athavale says.

Their home is one of three side-by-side certified "passive houses," meaning they meet the standards set by the Passive House Institute in Darmstadt, Germany. 

Designed by Boston-based RODE Architects and built by developer Dmitry Baskin of Passive House Construction, they use airtight construction, triple-glazed windows, a foundation made from 12-inch concrete slabs set on 8-inch foam blocks, and strategic shading to bypass conventional heating and cooling systems.

The heating and cooling comes from small mini-split style (heat) pumps, connected to a condenser outside the house when necessary. The house also uses an ERV (energy recovery ventilation) system to circulate the air to maintain a clean and fresh indoor air environment. In the winter, the system pulls heat from the exhaust air and transfers it to the incoming air, thereby reducing the heating load, rather than burning gas or oil.

These air tubes run throughout the house to extract stale air and pull in fresh HEPA-filtered air; the system exchanges the total volume of air five to seven times a day. All three homeowners opted to install solar panels.

"Think of it like a double-walled thermos that keeps your coffee hot all day, but on an even larger scale," says Kevin Deabler,a co-founder and design principal of RODE.

Extreme weather conditions, coupled with increasing wildfire smoke and pollution, have made the idea of a tightly sealed home with highly filtered air more appealing, says Ken Levenson, executive director of the Passive House Network, a nonprofit that focuses on passive-house education. Passive-house technology reduces carbon emissions because people use less energy, and it allows people to live more comfortably while paying lower energy costs, he says.

John Barrows of P3 Builder Group, based in Bridgehampton, N.Y., which has been building sustainable homes in the Hamptons for eight years, estimates a passive house costs 5% to 15% more to build than traditional homes. 

Highly insulated windows (that can be opened as usual) and exterior materials are expensive, as is adding solar panels; plus there is the time it takes to get the home certified -- whether by the institute in Germany or by Phius, a Chicago-based nonprofit. He says the cost differentials can be reduced with good planning. Other owners balk at the effort needed to live in a passive house, because its systems are different from just turning on the heat or air conditioning when you get home, he adds.

What started as a few states and cities giving tax credits for multifamily buildings adopting passive-house technology has grown more robust nationwide: Almost 16,000 units of Passive House multifamily housing -- apartments or townhomes -- have been built or are in the process of construction nationwide. Because some projects don't certify or aren't listed in certification databases, this is a snapshot of a larger trend, says Levenson.

Massachusetts is at the forefront: This year the state implemented a new building code in various municipalities, including Boston, mandating that all multifamily projects over 12,000 square feet meet the passive-house standards starting next year. While there are still only about two dozen certified single-family passive houses in the state, there are more than 160 multifamily projects in the works, 40% of which are designated low-income or affordable, says Aaron Gunderson, the executive director of Passive House Massachusetts.

To reach the price point that would make these single-family homes a viable investment, Baskin and Deabler brainstormed ways to differentiate them enough to make people willing to pay a premium.

RODE designed the homes to fit into the neighborhood, with simply pitched rooflines and side garages. Each of the houses has four bedrooms, three bathrooms, and an open kitchen and living area. And all have white cedar built-in cabinets, white oak floating stair treads, and a mixture of porcelain tile and hardwood plank flooring.

Still, each looks unique because of the lifestyles of the owners. One is dominated by children's toys and family photos; another is minimalist and spotless; the third has colorful walls, stylish lighting fixtures and a stand-alone tub.

Truc Luong, 39, an aerospace engineer, and Mary Ho, 39, an emergency-department nurse, bought one of the homes in July 2021 before construction had even started. Their daughter was born that year and they wanted more space.

Luong estimated that buying a newly built home in Boston would be about $1.2 million. He had heard of passive houses, and believed what seemed like a high price for the home ($1.4 million) would be worth the extra $200,000 because of the comfort and the savings he would get from not having traditional heating and cooling systems. 

Luong tracks how much energy the house is using by the hour on an app and estimates he is saving about $700 to $1,200 a month.

Brett St. Onge, who lives in the minimalist house, also liked the idea of being able to control his environment. The 50-year-old engineer at Apple moved back to the Boston area, where he grew up, last year after 27 years in Austin, Texas.

He says his new house, which he bought for $1.5 million and moved into in July 2022, is well insulated. He likes that he can adjust the temperature inside by raising and lowering the window shades. His monthly electric bill is negative, so he gives the credits to his parents to pay their electric bill. They both use the same energy company.

Athavale and Datar bought their house for $1.4 million in July 2021, when it was still in the framing stage. They were living in an 800-square-foot condo in the Jamaica Plain neighborhood of Boston. When Covid hit in 2020, they both started working from home and wanted more space.

Athavale says they view themselves as environmentally conscious -- they drive an electric car and recycle -- but they had never heard of the concept of a passive house. Datar has noticed since they moved in that her seasonal allergies have disappeared.

They say the passive-house certification reassures them that what they bought is real and that the environmental benefits will add to the home's market value.

"We were a little worried about whether the technology was legitimate, but we are both scientists so we are hardwired to trust the numbers," says Datar." [1]

1. MANSION --- Triple-Digit Heat, but No Electric Bill? --- Three certified passive houses in Boston were built to offer clean inside air, reduced emissions and little to no energy costs. Keates, Nancy.  Wall Street Journal, Eastern edition; New York, N.Y.. 04 Aug 2023: M.1.