Improving Laboratory Energy Efficiency Through Modified Exhaust Systems

Jeremy Lebowitz, PE

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Sep 23, 2021

The rapid expansion of biotech, pharma and gene therapy industries has resulted in a greater demand for laboratories. Laboratories, however, pose a challenge to energy efficiency and sustainability. They are among the highest energy-usage buildings and consume more than two to three times more energy than most other commercial buildings.

More than half of a laboratory’s energy load stems from maintaining the required level of ventilation needed to protect occupants’ health and comply with applicable codes and standards. It can be a challenging task to achieve energy reduction and personnel safety, two goals that seem mutually exclusive. Fortunately, there are design solutions available that can achieve reductions in laboratory energy usage without sacrificing safety. One strategy is to install or retrofit a manifolded exhaust system.

Jensen Hughes in collaboration with Arup recently completed a substantial overhaul of the International Institute for Sustainable Laboratories (I²SL) Best Practices Guide for Manifolding Laboratory Exhaust Systems. As the first major update in 14 years, this revision highlights the significant benefits of manifolded exhaust systems along with numerous enhancements geared toward advances in available technology and model codes. Moreover, since the “floor” of basic laboratory design has been raised considerably in the last decade, the guide includes updates to the baseline laboratory exhaust configuration as well as what constitutes better design principles.

Manifolded exhaust systems combine the exhaust streams from multiple laboratory areas prior to leaving the building. This approach can help decrease both first-cost and operational expenses while allowing for additional benefits including increased contaminant dilution, enhanced personnel safety and a reduction in the overall amount of equipment and floor space required for the exhaust system.

Equally important, manifolded exhaust systems provide substantial energy savings by reducing the amount of energy consumed by ventilation. A basic manifolded laboratory exhaust system utilizing a large centralized exhaust duct with one or more primary fans is much more energy-efficient than a separately ducted exhaust system employing multiple fans working independently. As discussed in the guide, the adjustable airflow system, increased energy recovery opportunities and reduction in both fan power and amount of energy required to disperse exhaust plumes all help to improve energy efficiency.

The guide also recommends several design practice enhancements that, when applied to the basic manifolded system, can produce even greater energy efficiency without extra additional expense or complications. Suggested strategies include using air volume (VAV) systems and variable speed drives (VSDs), lowering manifold duct static pressure during off-hours, performing dispersion analyses and monitoring wind speed/direction and exhaust plume chemical concentration levels to allow for reduction in plume height and bypass volumes.

Unfortunately, the codes and standards have not adapted as quickly as technology to address this specific opportunity to improve laboratory efficiency. Both mechanical and building codes recognize the need for manifolded exhaust systems but they are still largely configured to offer prescriptive guidance on how to design laboratory exhaust. While this approach is a convenient shortcut, it often overlooks opportunities for optimization which require more up-front engineering. Instead, it encourages features that are especially attractive to developers such as right-sized systems that offer greater flexibility and reduced operating costs over the life of the building.

When installing or retrofitting an exhaust system, it is important to employ professional engineers with expertise in managing the code approval and design process. Click here to learn more about how Jensen Hughes can help ensure your laboratory building’s exhaust and other protection systems are optimized for your needs.