The result is 90 percent lower energy consumption than comparable buildings — and heating costs below $50 per apartment per year.
In recent years, average rent for a one-bedroom apartment in Brooklyn’s Bushwick neighborhood has skyrocketed to more than $3,000 a month, excluding utilities. That’s why New York City’s Department of Housing Preservation and Development (HPD) and Ridgewood Bushwick Senior Citizens Council (RBSCC) came together to develop Knickerbocker Commons.
For qualifying households, monthly rent for a one-bedroom apartment in the community’s six-story, 24-unit multi-family building at 803 Knickerbocker Avenue is less than $700. RBSCC also wanted to cut tenant utility costs radically without compromising comfort. So, they called upon Chris Benedict, R.A., to design an ultra-low-energy building. Henry Gifford, who works for Chris Benedict, designed the mechanical systems for the building.
The team combined several technologies, such as continuous exterior insulation, energy recovery ventilators, sealed combustion boilers, and individual room thermostat controls, including Danfoss thermostatic radiator valves (TRVs). According to Gifford, the result is 90 percent lower energy consumption than comparable buildings — and heating costs below $50 per apartment per year.
“The 803 Knickerbocker Avenue building was completed in 2014,” says Gifford. “We used proven building-science concepts that could be applied to any high-performance building. No energy-efficiency rebates defrayed the cost of the low-energy technology we used. In fact, we delivered an extreme level of efficiency and comfort without adding to the construction cost.”
TRVs turn in rewarding energy savings
Utilizing room thermostat control into the integrated building design has produced extraordinary energy savings. Despite its 34,581 square feet, the property’s peak heating load is only 127,000 BTU/hour.
“This is an incredibly low heat load for a building of this size,” says Gifford. “But, just because the load for space heating goes down doesn’t mean the domestic hot water load is reduced. We put two small, sealed-combustion gas boilers in a mechanical room on the roof. The boiler capacity is primarily used to make domestic hot water and, secondarily, heat the building — which is opposite from the responsibility of most boilers in other buildings. We have four storage tanks for the domestic hot water, and we use the smallest, most efficient pumps possible to circulate water in the hydronic loop.”
A 1/8-horsepower pump supplies a two-pipe hot water system, which runs whenever the outdoor temperature is lower than 55°F, serving the entire building. The Danfoss valves on each radiator control flow through each radiator.
Certified with the Passive House Standard
The ultra-low energy performance, comfort, and aesthetics of 803 Knickerbocker have been widely recognized. It was the first midsized apartment building in the U.S. to be certified to the Passive House Standard, and was recognized in New York City Mayor Bill de Blasio’s One City Built To Last program as an innovative approach to reducing the city’s carbon footprint.
The building is further proof that an integrated, holistic approach to design is practical. It also has helped spur changes in NYC building code and zoning regulations to enable construction of more ultra-low energy buildings.
However, most important to Gifford is the legacy of comfortable tenants and property owners. Gifford notes, “Danfoss TRVs have been successfully used for decades, especially in Europe, where it seems almost every room has its own radiator control. Since 803 Knickerbocker opened in 2014, there have been zero tenant complaints about heating. When you can make both tenants and property owners happy in Brooklyn, it shows using thermostatic radiator valves for every room really works.”
About Solutions magazine:
Danfoss Solutions is edited by Danfoss in North Amerika and provides relevant, up-to-date industry news and insights to the professionals within the many industries Danfoss serves. Topics include emerging trends, updates on U.S. and global policy and other newsworthy events, as well as information on notable Danfoss solutions and products.
This issue’s theme is Driving the High-Performance Building Transformation and includes two cross-segment case studies - an elementary school in Florida, and a University Lab in North Carolina- and a Heating Segment multi-family residential building in New York.