Laboratory buildings are notorious energy hogs, and organic chemistry research laboratory buildings are particular offenders. Not only do these buildings commonly employ once-through air systems, but they also require a rigorous approach to ventilation to protect researchers from breathing the harmful vapors of the volatile organic solvents omnipresent in organic chemistry research.
“Many research activities that just 10 years ago would have been performed on the benchtop are nowadays performed under exhaust ventilation via chemical fume hoods, snorkel exhaust, or other point exhaust systems,” says Jim Blount, associate principal at Perkins+Will.
In addition, organic chemistry research, and scientific research in general, is using more equipment that requires direct exhaust, such as rotary evaporators, solvent purification systems, and high-throughput samplers. Understandably, researchers with a voice in laboratory design are increasingly requesting the widest fume hoods possible, abandoning the once-standard four-foot-wide fume hoods in favor of eight-foot or larger models that can accommodate equipment and provide adequate preparation and work-up space.
With 160 eight-foot chemical fume hoods as well as 74 point exhaust systems, 74 vented chemical storage cabinets, and 37 equipment exhaust locations in addition to a once-through air system, Yale University’s Chemistry Research Building promised to be a severe energy guzzler unless measures were taken to reduce energy costs. To address this problem, the design team focused on rethinking several aspects of fume hood design and reducing overall ventilation to laboratory spaces, as well as implementing other energy-saving strategies such as daylighting.
Throughout the project, the team concentrated on implementing as many energy-saving measures as possible, while ensuring adequate health and safety protections for students and faculty.
“From the very beginning, we did life cycle cost analyses on some of these measures to see how much they would benefit the University and the users,” says Lee Schofer, senior associate and project manager at Vanderweil Engineers.
Two of those analyses—of constant versus variable air volume fume hoods, and of two different types of fume hood sashes—revealed ways to save millions of dollars in energy costs over the building’s life cycle.
“The real success of the project wasn’t just saving energy,” says Schofer. “It was the fact that we were able to save energy with the buy-in of the users, the maintenance staff, and the University’s environmental health and safety officers, as well as the local code authority. We went to a great deal of effort and expense to make this a truly collaborative endeavor.”
Fume Hood Design Innovations
“Most of the time, researchers aren’t going to be that excited about saving energy,” says Schofer. “They just want to do their work safely and efficiently.”
The researchers’ natural desire for an unencumbered workspace—which in the lab would translate to the widest possible chemical fume hood, with a wide-open sash—clearly was not an option from an energy standpoint. However, it was also true that no individual researcher would need to use the entire eight-foot width of the hood at one time. An effective compromise was struck in the implementation of a combination sash, with a custom-designed aerodynamic airfoil. In addition to sliding up and down like a normal fume hood sash, the combination sash contains glass panels that slide horizontally within it. With a maximum 28″ x 34″ horizontal sash opening, the combination sash provided openings sufficient to accommodate the full spectrum of research activities conducted at the Chemistry Research Building.
The combination sash was shown in a life cycle cost analysis to yield a 25 percent energy savings compared to a standard sash with a vertical opening of 14″. Additionally, as it turned out, the researchers actually preferred the combination sash to the conventional model.
“This is the first instance on campus where we have used a large number of these types of sash configurations,” says Rob Klein, associate director at Yale’s Office of Environmental Health and Safety, “and we were worried that individuals would find them too confining. Instead, people have indicated that they do like them.”
“They found they could have a higher opening in the hood,” says Schofer.
The researchers especially appreciated the added safety they could achieve by using a horizontal sliding panel as a body shield, reaching around the sides of the panel to perform particularly hazardous work.
Another significant savings was achieved by employing variable-air-volume (VAV) chemical fume hoods equipped with zone presence sensors. A life cycle cost study of the devices showed that they could reduce energy use by an additional 40 percent by reducing exhaust through the hood when the floor area in front of the hood was unoccupied.
This exhaust-rate reduction enabled by the zone presence sensors combined with the 25 percent reduction provided by the combination sash resulted in a total exhaust-rate reduction that exceeded that permitted by NFPA guidelines. To justify this reduction, Klein and several of his safety colleagues spearheaded an investigation into the efficacy of various fume-hood exhaust rates in mitigating explosive environments caused by chemical spills within hoods. The team purposely spilled various common solvents within fume hoods and measured the evaporation and resulting solvent concentrations in exhaust air under different hood operating conditions.
Klein’s findings, which were published in the American Chemical Society journal Chemical Health and Safety (March/April 2004), were very clear and extremely advantageous to the project.
“What we confirmed,” says Klein, “is that solvent evaporation is a function of chemical vapor pressure and exhaust flow rates. With all other fume hood variables held the same, less total exhaust air does increase chemical concentrations, but you can significantly lower flow without creating an explosive atmosphere. In fact, we found that for common lab chemicals, we could lower flows nearly fivefold during non-use times and still maintain a safe fume hood environment”—for a net exhaust-rate reduction of 80 percent.
Armed with these results, the design team appealed to the local and state code authorities for an exception to the NFPA requirements—an exception that was granted.
Room Ventilation Innovations
In addition to making fume hoods more efficient, the project team also sought to optimize ventilation airflow into laboratory areas. The first step was finding out when researchers did their work.
“When we looked at the use patterns of Yale’s graduate-level chemistry research facilities,” says Blount, “we found that they were virtually unoccupied from about 2 a.m. to about 10 a.m. We wanted to develop systems that would respond to these large windows of unoccupied time.”
Laboratories are equipped with dual technology (ultrasonic/infrared) occupancy sensors, and airflow rates as well as lighting switches are keyed to the sensors. To ensure that the sensors could “see” all parts of the room—including the “shadow” areas cast by island benches and other obstacles—laboratories are equipped with three occupancy sensors apiece. In addition, the zone presence sensors on the fume hoods, which raised or lowered varied fume hood exhaust rates depending on whether a user was nearby, are also keyed to room ventilation controls to ensure a sufficient volume of air for the fume hoods to exhaust.
“With the three occupancy sensors, and the zone presence sensors for the fume hoods,” says Schofer, “we were pretty heavily instrumented.”
How much could airflow be reduced when labs were unoccupied? Best-practices standards of the day dictated 12 air changes per hour for all lab spaces, occupied or not. The team, however, proposed reducing the airflow in unoccupied lab spaces from 12 air changes per hour to six.
“At the time, this was almost heresy,” says Schofer. “Everyone assumed that you had to have at least 12 air changes per hour in a lab, especially a chemistry lab.” Yale’s Office of Environmental Health and Safety, reluctant at first, eventually warmed to the idea. “As we got more into the design and they could see that we were providing adequate chemical storage and room pressurization, they were willing to try it,” he says.
The measure, says Schofer, has resulted in big-time energy savings, with no reduction whatsoever in air quality.
Building Design and Layout
The Chemistry Research Building (CRB) is Yale University’s third building on Science Hill, joining the Sterling Chemistry Building and the Kline Chemistry Building. The 100,000-sf new building is dedicated to organic chemistry, with space for 12 PIs and 148 graduate students.
“This building really is based around academic research in the lab,” says Klein.
The building layout consists of a simple and modular rectangle with technical program on one side and non-technical program on the other. Faculty offices are co-located to encourage collaboration among the groups. Graduate student offices are located directly across from the main labs.
The 37 lab modules are each configured for four investigators, with four chemical fume hoods, four bench spaces, one central island bench, four sinks, and an equipment zone. Write-up spaces and lab support spaces are accessible via a corridor within the lab. Breakout and collaboration spaces are situated along the main circulation spine and in central locations.
Daylighting is a simple yet powerful design strategy that the design team employed in abundance throughout the Chemistry Research Building. Besides enabling significant energy savings on electric lighting, the sunlight streaming through the laboratory windows creates a pleasant, vibrant environment in which researchers can do their best work.
Despite the myriad reductions in ventilation and fume hood exhaust rates, users express high levels of satisfaction with the new facility.
“Over the first year of operation,” says Klein, “the volume of complaints related to odors, spills, and smells was 50 percent less than at Yale’s older laboratory buildings. On a daily basis that classic organic chemical odor is essentially imperceptible in the rooms.”
“The big success of this project,” says Schofer, “is that in all aspects, whether it’s fighting fires, paying for energy, health and safety, efficiency of use, everybody just seems satisfied with it.”
In a major triumph, however, the building has achieved LEED certification—thought by many to be impossible for a building of this type. “I had many a heated debate as to whether we could end up with a LEED-certified laboratory,” says Schofer. “But we were able to work within the LEED regulations and get the certification.”
By Deborah Kreuze