In the Observatory Hill neighborhood of Cambridge, Massachusetts, Betsy Harper (MBA 1984) has built an oxymoron: a brand-new, historic home. The recently completed structure combines traditional architecture and the latest in high-efficiency building science. It is a proof of concept that could spark a home-design revolution.

A Passive House is designed to be ultra-energy efficient. Some, like Harper’s Victorian, achieve net-zero-energy demand by pairing low-energy use with solar panels for energy production. Harper’s home is designed to achieve net-positive-energy production—because it uses so little energy, the solar production will far exceed the annual energy demand. Many high-performance homes are boxy, modern structures. But an energy-efficient house can’t leak air where walls meet, as typical houses do, making more traditional and elaborate creations a challenge. Harper wanted to prove that the Passive House model could be implemented within a variety of architectural styles, opening the door to wider adoption in many different settings. Harper, who spent the first 20 years of her career in finance, launched Birchwood Sustainable Development in 2018 to take on the task. “As I contemplated what I wanted to do for the second half of my career, it became clear that I wanted to work on climate change issues and help us get to the goal of zero-carbon emissions by 2050,” she recalls.

During the building process, the innovative five-bedroom, five-and-a-half-bath house was a show home, attracting dozens of architecture professors and students, engineers, other developers, and government policy-makers to tour the site. Harper hopes more people will recognize the benefits of this approach to house design. Though a single-family Passive House can require 10 percent to 15 percent higher up-front investment, the lower energy and maintenance costs can offset the expense. And she estimates that larger dwellings can be built for a 0 to 2 percent premium, making them a potential next project for Birchwood Sustainable Development. “The biggest market transformation is really happening in large-scale multifamily buildings, particularly in low-income residences,” Harper observes. “At 25 units or more, you have real economies of scale.”

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