When Harvard University completed its Blackstone South building in 2006, the process of improvement was only beginning. In its ensuing seven years of operation as a home for the school’s Campus Services department, the building, which received Platinum certification under LEED for New Construction, has been continuously tinkered with and studied. After all, Blackstone South houses the school’s engineers, sustainability experts, security facilities, and facilities staff. “We run the university-auditing program, so it was obvious we should look at our own building,” says Andrea Trimble, senior program manager for Harvard’s Green Building Services department.
The design by Boston firm Bruner/Cott renovated—and unified as one 42,000-square-foot structure—a trio of brick buildings from a coal-fired electricity plant dating back to the 1890s along the Charles River across from the Harvard Business School. A 100-foot-long glass light slot over the former alleyways, coupled with a central stairway atrium, flood the interiors with natural illumination. Natural ventilation and a ground-source heat pump helped meet aggressive energy-efficiency goals of 40 percent over the ASHRAE 90.1 baseline (in summertime), all supervised by an extensive building automation system that would go so far as to instruct users when to open and close their windows. The surrounding surface parking lot was transformed into a landscaped courtyard using earth excavated during construction; it requires no irrigation. A bio-retention pond helps catch runoff from daily oil-truck deliveries to the university’s steam heating plant next door, and the historic brick walls were insulated with innovative open-cell foam delivering an efficient R-19 value. Potable water consumption was reduced 30 percent compared to a building using code-maximum fixtures.
At the time of its completion (on a budget of $10.5 million), Blackstone South was the highest-scoring LEED-certified renovation in the nation and was the oldest building to achieve Platinum; it was also the first Platinum-certified building in the Ivy League. “It was seen at the time as a laboratory for thinking about how buildings could be retrofitted and what components could be employed,” says Leland Cott, FAIA, of Bruner/Cott.
Yet both architect and client were surprised to learn during a 2008 in-house energy audit that the building was consuming 30 percent more energy than they had expected. The original building modeling, they found, didn’t take account for the continuous, 24/7 air handling that was necessary for the campus security facilities—air handling that did not need to be applied to the rest of the building’s offices. In addition, the air could have been shut down during nights and weekends, but the energy-recovery wheel was malfunctioning, losing the chance to save 50,000 kilowatt-hours per year and necessitating replacement under warranty. The security facilities, with their extensive computer and video systems, could also have been cooled using outside air from November through April. But addressing these measures as part of an ongoing commissioning and management process has improved energy performance so that it’s now performing not 40 percent better than code as had been targeted, but 60 percent better.
In 2011, another audit was performed, which yielded several opportunities for smaller savings and quick payback, such as upgrading lighting and reducing plug-load use. After this process, Blackstone South successfully sought LEED for Existing Buildings: Operations & Maintenance at the Platinum level, and, at the time this article was printed, it is one of only five projects in the world to possess both this and Platinum LEED-NC certification. The project also earned an Energy Star rating of 96.
With scores of LEED-rated buildings and interior projects across the Harvard campus, Blackstone’s initial performance glitches have made its high efficiency all the more of a model today. “This is the next big frontier for us: making sure they perform,” Trimble says of Harvard’s campus-wide plan for ongoing commissioning and auditing. “We’re just starting to ramp up internal capacity to do that more fully.”