Laboratory buildings are consistently one of the highest energy consumers on any campus; typically costing 3-5x more per square foot than other buildings. Bucknell University’s Rooke Science Center was no exception; requiring over $1.0M per year in operating expenses. Entech was selected to identify strategies to improve efficiency of the building’s HVAC systems and lower costs. Entech identified and recommended projects for the entire building and was selected to design six projects within the biology portion of Rooke. The projects were predicted to reduce energy costs by nearly $300,000 per year with a simple construction payback period of only 3.2 years, saving Bucknell almost $2.0M over the next 10 years after construction costs were recouped.
Biological and chemical hoods and storage cabinets can account for significant HVAC energy inefficiencies in most laboratories. The exhaust systems are necessary to expel harmful or unpleasant fumes, but to do so, they also exhaust conditioned air, typically overtaxing the heating and cooling systems. Furthermore, most laboratory HVAC systems do not recondition any return air drawing 100% outside air as a safety precaution.
Rooke’s Biology rooms were countinuously running their 35+ chemical hoods, exhausting approximately 74,000 cfm. Entech examined the hood usage and space utilization by interviewing Bucknell faculty and, calculated the necessary exhaust rate to be 54,000 cfm. That 20,000 cfm reduction of exhaust accounted for a majority of Bucknell’s energy savings.
Exhaust reductions were primarily realized by the following methods: (1) manual on/off controls on hoods not in use 24/7; (2) addition of traditional exhaust return vents, controlled by variable air volume (VAV) boxes to rooms that open when hoods are off, to make the space function properly when hoods not in use; (3) Variable Frequency Drives (VFDs) to control fan speeds of supply and exhaust automatically based on demand; (4) decommission of hoods that were no longer necessary.
Bucknell’s actual cfm reduction was close to 30,000 cfm, significantly increasing their savings and reducing their payback period. The same methodology and approach was used to upgrade the other half of the science center, which houses the chemistry department, effectively doubling Bucknell’s savings for the entire building, at a similar project cost and payback period.