DCAS Bronx Government Building

Fujitsu VRF Retrofit


A 100-year-old building, with a hard to access roof and disjointed heating and cooling systems, causing comfort levels to be far too low and energy expenses far too high. In lock-step with New York’s march toward electrification (Local Law 97 / LL97), NYSERDA (New York State Energy & Research Development Authority) has set an ambitious goal to reduce the 2025 energy-use forecast by 185 trillion BTUs. DCAS has begun a systematic program of installing high efficiency heat pump systems in facilities that will yield the greatest savings.


Beyond hoisting an outdoor rooftop unit through a removed skylight in lieu of a crane, a variety of Fujitsu AIRSTAGE VRF and Halcyon mini-splits were used to replace the steam heating system. The largest room in the building, an expansive conference space, was previously served by a rooftop unit containing a DX coil and semi-hermetic compressor for cooling, and a gas-fired furnace. This did a poor job of responding to the fluctuating human load. “The conference room is now one of nine VRF zones in the building,” Laidlaw says. “We installed three, three-ton ceiling cassettes. We’ve witnessed much better temperature modulation in response to quickly changing loads.”

Other zones in the building are served by a variety of indoor units. Two eight-ton, high-static air handlers are used, one on the first floor and one on the second. Two five-ton vertical air handlers condition various offices. Wall-mount units are used in a storage area and a custodian’s office.

“Standby heat loss from the old steam boiler used to keep the basement hot,” Laidlaw says. “So we installed a three-ton ducted unit to keep the space above freezing.”

In total, eight condensing units and 11 indoor units were used for 46 tons of capacity. Once eight of the 11 VRF systems were running, work on the project was paused. From July through October of 2019, energy use data was collected. Electric and oil bills were compared to the same months of the previous year, showing a 34% savings.

“Because three units serving the first floor weren’t operational during the initial comparison period, we fully expect that the savings will be higher once collection of data includes the entire building—around 50%,” Donovan says. “All the units are now installed, we’re just waiting to connect power to the last few Airstage units.”

Products on the Job

(1) Fujitsu AOUA288RLBVG1 V-II Heat-Pump ODU
(1) Fujitsu ARUH36TLAV High static pressure duct IDU
(2) Fujitsu ARUH48TLAV High static pressure duct IDU
(2) Fujitsu ARUV48TLAV Vertical Air Handler IDU
(1) Fujitsu ARUH96TLAV High static pressure duct
(1) Fujitsu UTY-DTGYZ1 Touch panel controller(Internet access)
(5) Fujitsu UTY-RNRUZ2 Wired RC (Touch)
(3) Fujitsu AOU60RLAVM J-II Heat Pump
(2) Fujitsu ARUV60TLAV Vertical Air Handler
(1) Fujitsu ARUH60TLAV High static pressure duct
(1) Fujitsu AOUA120RLBV1 V-II Heat-Pump ODU
(2) Fujitsu ASUB24TLAV Wall Mount IDU
(3) Fujitsu AUUB36TLAV Ceiling Cassette IDU
(1) Fujitsu UTY-RNRUZ1 Wired Control