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Can a remodeled 1920s home revolutionize green building?

Harvard’s HouseZero, an ambitious retrofit of a decades-old building, is a lab for energy-efficient design

The HouseZero project at Harvard retrofitted a pre-war home on campus, creating a model of energy efficiency.
The HouseZero project at Harvard retrofitted a pre-war home on campus, creating a model of energy efficiency.
Michael Grimm

A Harvard program to retrofit a campus building and create a living laboratory for energy-efficient architecture officially opens today, aiming to develop techniques and technologies to make the built world more sustainable.

The goal of the HouseZero project, to create a building that produces more energy over its lifetime than it uses, is potentially transformative. To accomplish this, the renovated building was designed by the school’s Center for Green Building and Cities (CGBC) with strict performance targets in mind: nearly zero energy for heating and cooling, zero electric lighting during the day, operating with 100 percent natural ventilation, and producing zero carbon emissions.

“We’re shattering the belief that you need to build new buildings to be efficient,” Ali Malkawi, a professor of architectural technology who leads the CGBC program, told Curbed. “We want to show how this can be replicated almost anywhere, and solve one of the world’s biggest energy problems, inefficient existing buildings.”

HouseZero depends on extensive daylighting and automatic ventilation to decrease heating, cooling, and lighting costs.
Michael Grimm
“We’re shattering the belief that you need to build new building to be efficient.”
Michael Grimm

The demonstration home, a retrofit of a prewar, stick-built home led by Snøhetta, with Skanska Teknikk Norway serving as the lead energy engineer, wants to show that affordable upgrades can make a massive difference.

HouseZero attacks one of the largest sources of energy usage and carbon emissions: the existing building stock. Currently, existing U.S. buildings 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. As Malkawi says, most of the building stock in the U.S. has already been built.

The HouseZero home, meant to be a new office for the CGBC, provided designers with a model challenge. The inefficient, aging building needed air conditioning units in the summer and heaters in the winter, and due to its location in an historic district, pinpoint accuracy in its retrofits to meet existing building codes.

“We wanted the building to breathe, and leaving it open makes it more adaptable.”
Michael Grimm
The retrofitted home uses extensive daylighting and natural ventilation, augmented by an sophisticated window actuation system, that uses software and sensors to adjust, open, and close windows continuously.
Michael Grimm

Unlike other strict building standards, such as passive house construction, which seeks to seal off the environment to achieve energy efficiency, HouseZero rejects the conventional “sealed box” approach in favor of a building that reacts to its environment. The retrofitted home uses extensive daylighting and natural ventilation, augmented by a sophisticated window actuation system that uses software and sensors to adjust, open, and close windows continuously. By working with, instead of fighting, the environment, the CGBC’s project shows how more reactive architecture can sharply cut energy use while increasing comfort.

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

By developing better and financially viable frameworks for transforming old structures into energy efficient homes or commercial space, developers or homeowners can capture significant energy savings without investing in the materials and resources needed to create an entirely new structure.

There’s still much to learn from the remodel, and an initial energy audit will show eventually show how the retrofitted structure performs over time. Built with an extensive network of hundreds of sensors, HouseZero will provide detailed information about the home’s environment, including minute temperatures fluctuations. The information can then create computational simulations that can be used to develop even more efficient and sustainable structures. It’s not just an office, it’s a lab.