Published By: Joe Parsons
When most people think of geothermal heating and cooling, they think of single-family homes.
L+M Partners, ZBF Geothermal, and ClimateMaster® paved the way for Beach Green Dunes II in NYC to bring all the cost-saving and carbon-reducing benefits of a water source heat pump system to multi-family, affordable housing units.
“The developer, L+M Development, wanted to do geothermal on a project. They had committed to “passive house standard” construction. That was the first step. In the first phase, their development partner had successfully used air source heat pumps. To further reduce the operating cost of these affordable housing units, geothermal heat pump systems were selected for the second phase.” said Zach Fink, founder of ZBF Geothermal in Long Island.
The eight-story building is situated on 121,000 GSF and includes 127 rental apartments and 50 parking spaces. Because it was designed from the ground up as passive and affordable housing in New York City, the developers invested heavily in advanced power and space conditioning technology to reduce overall operating expenses.
“In a single-family home, you would run a manual J load calculation, enter the results in geothermal software and get approximate energy usage. On multi-family, commercial and industrial buildings, you run an 8760 energy model. You’re predicting what the heating and cooling loads of the building are on an hour-by-hour basis.
“Following this, energy modelers use a data set that reflects the last 15 years to capture a little bit of rising outdoor air temperatures. That feeds into a financial analysis tool to determine what the actual operating cost of the system is. You can then break that down to the fan power on one heat pump. Where residentially, you look at the system as a whole,” said Zach Fink.
The results for Beach Dunes II exceeded the developers’ expectations. Tenants can expect to pay as little as $10 a month for cooling their apartments in the summer.
Because the Beach Dunes II complex is within 200 feet of a subway structure, the New York City Transit Authority (MTA) has jurisdiction, requiring special approval from their Outside Product Division.
Until recently, MTA required steel casings around all underground boreholes to prevent structural footings from crumbling. This would have dramatically increased the cost of the geothermal loop installation.
To circumvent this issue, the MTA was presented a safety plan that included adding seismic meters to the structure, surveyors verifying the building didn’t move after drilling, and the closest boreholes to the building drilled first. Upon review, MTA granted borehole drilling without the need for steel casings.
The geothermal loop for Beach Dunes II is a vertical, closed-loop system. Thirty-six boreholes were drilled at a depth of 500ft under the courtyard of the property. Upon landscaping completion, no one knows they are standing on top of a geothermal loop field.
The result of Beach Green Dunes II's construction with ClimateMaster geothermal heat pumps is nothing short of astonishing. Heating and cooling for this sizable apartment building are an estimated $25,000 a year. That’s 1/4 the cost of conventionally heating and cooling a building.
With Beach Green Dunes II winning New York Geo Exchange top job and setting the new standard for borehole drilling near a subway station without steel casings, the future is bright. In fact, several more multi-family buildings are on the horizon for geothermal heating and cooling in New York City.
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