3 Van de Graaff Drive
The facility at 3 Van de Graaff Drive in Burlington, Massachusetts is a 240,847 gross ft2 Class A commercial office space with a four-story tower, a two-story section, and a single story section. The building is a brick veneer and window walls over steel construction and was built in 1998.
The building is 240,847 gross space square feet. This yields an EUI of 186 kBtu/ft2/yr including data and UPS rooms or 116.52 kBtu/ft2/yr for the building excluding the data center use.
Target energy use for this type of building is taken from the US DOE’s Energy Information Administration CBECS energy use table for office buildings located in New England. Their number is 99 kBtu/ft2/year. This comparison indicates that this building has an EUI higher than the average.
EE&D engineers identified 9 Low Cost / No Cost Measures and 6 Capital Improvement Measures. If all of the Energy Conservation Measures identified in Table 1 and Table 2 are implemented, the EUI of the building would be reduced to 145.9 kBtu/sf/year including the server room use or to 78.7 kBtu/sf/year if the server room use is excluded. This would save the facility an estimated $196,813 per year.
Cooling and Ventilation System
The property is equipped with fifteen Trane roof top units (RTU’s) ranging from 30 ton to 130 ton. Each unit has air-cooled compressors with isolation dampers and economizers. Each unit also has a supply fan equipped with a variable frequency drive, which is controlled by a duct static pressure, and a powered exhaust fan.
There are three ring duct loops or zones. There are seven 50-ton units and one 30-ton unit located on the first floor roof, which serve the first floor ring duct zone. The second floor roof houses three 50-ton units, which serve the two story ring duct zone. The fourth floor roof has four 130-ton units, which serve the four-story ring duct zone. These units stage on together and the fans’ speed modulate to maintain the ring duct static pressure and cooling set points. The static pressure set point is controlled by the building management system and is set at 1” static during the cool months and 1.5” static during warm months. All fresh air is provided by these fifteen RTU’s and is set at a minimum of 20% outside air.
Supplemental Data Center Cooling Equipment
The facility has seven uninterrupted power supply systems (UPS) serving tenant data centers. These data centers are conditioned by stand-alone Liebert Data Center HVAC systems, which control the humidification and dehumidification. The data center set points are tenant controlled. The UPS room has three CAC units, the Sungard data center has six CAC units, the Raytheon data center has three CAC units, the Sophos data center has two CAC units, the Sophos first floor lab has two five ton split systems, Open text has two (2) ton split Sanyo units in its LAN room, Health Edge has a five ton split unit in its LAN room, SAP has two (2) ton split Sanyo units in its LAN room, and Sprint has a five ton split unit in its LAN room. The glycol loop has two Leeson 15 HP pumps equipped with variable frequency drives. These pumps run lead-lag when needed and change over on Wednesdays.
Heating System
Hot water is provided by two 9,000,000 BTU Bryan gas fired boilers with a modulating combustion air intake damper and gas valve controlled by the energy management system. These boilers run lead-lag and change over on Wednesdays. There are three heating loops each with a 10 HP pump equipped with a variable frequency drive. There is one loop for the first floor east, one for the first floor west, and one for the high rise. There is also a fourth pump that is used as a spare. Space heating is provided by perimeter hydronic radiant heating units as well as hydronic coils in fan powered boxes and variable air volume (VAV) boxes throughout the facility. Supplemental heat in common areas is provided by unit heaters or perimeter radiant heaters.
Target energy use for this type of building is taken from the US DOE’s Energy Information Administration CBECS energy use table for office buildings located in New England. Their number is 99 kBtu/ft2/year. This comparison indicates that this building has an EUI higher than the average.
As might be expected, the cooling and UPS use for the multiple data centers and UPS room (53%) account for over half of the total energy costs. This is due primarily due to the 24-hour cooling requirements for the computer equipment housed in these spaces. Because these are tenant-controlled spaces, no energy conservation opportunities were evaluated for these spaces.