By Susan Chaityn Lebovits
From the outside it looks like an ordinary building. But 1,500 feet below the street is the core of Boston University’s first geothermal building: six wells harness the earth’s energy to warm and cool the 95,000 square foot space- without the use of fossil fuels. This ground-source heat pump technology also eliminates the need for a boiler room and cumbersome heating, ventilation and air-conditioning systems, allowing for a 3,500 square foot roof garden in the heart of the city.
While the concept of geothermal energy isn’t new, there are a limited number of buildings in Greater Boston that have taken advantage of this technology. Not relying on energy sources such as oil, gas, and coal, saves dollars and slashes carbon emissions, leaving cleaner air and a lighter environmental footprint.
Since the temperature near the earth’s surface remains at approximately 55 degrees Fahrenheit year-round, the technology works no matter what the season. Water fills the wells that have been created and act as a conductor, transmitting energy from the earth to a heat exchanger, then into the building’s compressor, which disperses it. In the warmer months, heat is absorbed by the heat exchanger, and newly cooled air is blown into the building.
“The heat pumps work like a refrigerator,” says Patrick Watson-Hogan, president of ZVI Construction Co., which managed the project.
Despite the building requiring only five wells to accommodate the calculated tonnage, six were installed “a sort of the belt and suspenders for the system,” says Patrick-Hogan. An additional benefit, he adds, is that pumps can simultaneously cool one quadrant of the building and heat another.
While the initial cost of installing a geothermal system is approximately 30-40 percent higher than a traditional one, Watson-Hogan says the payback is between 7-10 years depending on weather conditions such as extreme winters for heating, or extreme summers for cooling. Since no fossil fuels are being burned, maintenance and operation costs are lower, as is the noise, a common by-product of traditional HVAC systems.
The building, former Fellsway Motor Mart, with its limestone façade and eight arches, is considered one of the most historic on Commonwealth Avenue in the town of Brookline, says Patrick-Hogan. In the 1920’s it was part of “The Automile,” named for the 100-plus dealerships that lined the street.
Part of the commitment made to the city in maintaining its historic look, Patrick-Hogan explains, was leaving a space between the back and front façade, away from the arches, which created a roof that is being landscaped.
“Over the last 25 years we’ve learned that tenants like the roof gardens,” says Patrick Hogan.“ People are looking for external spaces- a place to go and have lunch.” There are approximately eight roof gardens along Commonwealth Avenue.
Additional energy-efficient features in the geothermal building include CO2 sensors, which are tied into the fire alarm system; night setbacks on all the thermostats; energy efficient lighting with motion detectors; low VOC paint; and localized temperature zones. A lease obligation for every tenant in the building requires mandatory recycling.
“It’s just kind of changing people’s way of thinking so I don’t get too fettered by it,” says Patrick-Hogan. “You keep it as a low-key thing and it happens naturally.”