Harvard’s building a model for energy efficiency by renovating a decades–old home

When architects talk about building more sustainably, the conversation often turns toward new concepts for homes and offices. At Harvard, a group of students and faculty think they can push green design forward by looking back.

The new HouseZero Project, an initiative by the Harvard Center for Green Buildings and Cities (CGBC), has a lofty goal: creating a new prototype of ultra-efficient building that requires almost zero energy, relies on natural daylighting, and produces no carbon emissions. What makes the concept potentially revolutionary is that it’s based on affordable renovation. By retrofitting and redesigning the program’s offices in a prewar, stick-built home, the CGBC hoping to show how any existing building can become a model of efficiency, and cut emissions without requiring a huge investment.

“In the U.S., most of our building stock has already been built,” says Ali Malkawi, a professor of architectural technology who leads the CGBC program. “We’re shattering the belief that you need to build new building to be efficient. We want to show how this can be replicated almost anywhere, and solve one of the world’s biggest energy problems, inefficient existing buildings.”

Snøhetta

Greening existing building stock could make a huge difference in this country’s carbon emissions. Currently, existing U.S. building are responsible for 40 percent of the country’s energy consumption, costing owners more than $230 billion annually for heating, cooling, and power, according to the CGBC research. Malkawi sees better retrofitting as an immediate, high-impact means to help curb energy usage.

The program’s current home on campus, a mid-1920s stick-built home, offers a challenge, as well as a representative renovation project that could be repeated in Cambridge and across the country. One of scores of aging buildings in Cambridge, it’s very inefficient, requiring air conditioning units in the summer and heaters in the winter. The planned retrofit will cut energy usage and better connect the home with the outdoors, so it can take advantage of natural sources of heating, cooling and light.

The nearly century-old wooden building, located in an historic district, will require a pinpoint retrofit to meet the CGBC goals, since changes to the exterior are heavily regulated. The main energy-saving feature of the proposed design, based on years of CGBC research and overseen by Snohetta, the multinational architecture firm, is the geothermal wells, which can draw up underground heat or help cool the building, and a concrete slab, which functions as a thermal mass, soaking up heat like a sponge during the winter. A solar vent and triple-glazed windows will light the space while keeping in heat during New England winters, and a series of monitors and sensors, informed by algorithms, will control and conduct vents, windows, and circulation systems to further boost performance.

The goal is to make a building so efficient, Malkawi says, that the energy generated by the solar panel on the roof the power the office equipment and computers, will be almost secondary.

Center for Green Buildings and Cities

The HouseZero concept also seeks to stand out with its openness. Malkawi’s desire for a greener building includes creating a healthier space for students, faculty, and researchers, and for him, that also includes opening the space the outdoors. Unlike other energy-efficient designs, such as those used to obtain the strict passive house standard, this building will open up to nature and allow increased airflow and sunlight. Fresh air and better health, he says, are key parts of a more holistic idea of sustainability.

“We wanted the building to breathe,” he says, “and leaving it open makes it more adaptable.”

The project is just getting started. Malkawi and the rest of the department moved out of the building and into temporary workspaces just a few weeks ago. There’s no budget estimate yet, but when the project is finished, the team plans to release a detailed budget, plans, and energy audit, to show how homeowners could accomplish similar energy savings, and encourage them to do the same.

“We’re going to be collecting so much information from the building itself, it’s going to be like a lab,” he says.