Utilizing VAV Technology to Minimize Laboratory Exhaust Energy Consumption While Maintaining a Safe Laboratory Environment: Case Study of the Genentech Site Laboratory Exhaust Optimization Project
Brad Cochran, CPP, Inc.
Jerry Meek, Genentech, Inc.
Both Genentech and its parent company, Roche, take sustainability very seriously. Reducing the environmental impacts and costs of its products and operations is a key element in its sustainability plan. This can be difficult in a laboratory environment, where energy usage demands can be 10 to 100 times greater than in a typical office building. On its South San Francisco campus alone, Genentech has upwards of 20 laboratory buildings with nearly 3,000,000 cubic feet per minute (cfm) of exhaust fan capacity using approximately 20,000 megawatt-hours (MW-hrs) of electricity annually.
A majority of this capacity is focused within 14 of the laboratory buildings that are responsible for approximately 2,635,000 cfm of exhaust capacity using more than 18,000 MW-hrs of electricity annually.
To enhance its sustainability, Genentech has undergone a campus-wide laboratory optimization project on its South San Francisco Campus, with the goal of minimizing energy usage within the HVAC systems without compromising employee safety (another main element of its sustainability plan). The project includes reducing HVAC supply air requirements by minimizing air change rates where applicable, installing proximity sensors on fume hoods, and rebalancing and commissioning the HVAC supply system. However, the biggest energy savings are associated with implementing wind-responsive variable air volume (VAV) exhaust controls on its various laboratory exhaust fans.
A wind-responsive VAV exhaust system operates by connecting the building automation system to nearby wind speed/direction sensors. Because the performance of an exhaust stack is impacted by the wind speed at the top of the stack, there is a direct relationship between downwind concentrations of the exhaust plume and the local wind speed. As the wind speed decreases, the plume rise increases, reducing downwind concentrations. By knowing the current wind speed, the exhaust fan can be set to an optimum flow rate that minimizes energy consumption while maintaining a safe environment. Similarly, when the wind is blowing from directions where there are no sensitive receptor locations nearby, the volume flow rates through the system can be reduced.
This presentation will describe the techniques used to implement the campus-wide laboratory optimization project on the Genentech South San Francisco campus that utilizes wind-responsive VAV exhaust controls to save upwards of $1 million per year in energy consumption.
Biographies:
Brad Cochran is a registered professional engineer in the state of Colorado and has nearly 20 years of experience conducting wind-tunnel and mathematical modeling studies related to laboratory exhaust design. Mr. Cochran is active in ASHRAE and is currently serving as the lead author of Chapter 9, Exhaust Stack Design, in the upcoming latest edition of the ASHRAE Laboratory Design Guide. He is a voting member of TC9.10 Laboratory Systems. During the past decade, Mr. Cochran has focused on defining new design techniques to minimize the energy requirements for laboratory exhaust stacks. In 2005, Mr. Cochran developed the first laboratory exhaust system that utilized local wind data to minimize exhaust fan horsepower requirements. He has authored and presented several papers on the subject of energy-efficient laboratory exhaust design for ASHRAE, Labs21, R&D Magazine, Lab Manager Magazine, LabWize, the International Facility Management Association, the Air Movement and Control Association, and the Air and Waste Management Association.
Jerry Meek has worked for Roche Pharmaceuticals for 20 years as the utility operations energy manager. During this period, his Utility Operations Department has successfully reduced energy and water consumption, waste, and chemical use. Mr. Meek was honored as the 2002 Association of Energy Engineers Energy Manager of the year for Region 5, which includes seven western states. Mr. Meek was the co-chair for the Silicon Valley Leadership Group's energy committee for two years. Mr. Meek transferred to the Genentech South San Francisco campus in January 2010 to create and implement an energy efficiency and energy management program. Mr. Meek received a bachelor's degree in Industrial Technology from Cal Poly San Luis Obispo, certified energy manager status in 2004 and certified plant maintenance manager status in 2008.