Your Toolkit for Good Lab Exhaust Design

Mark Hallman, Rowan Williams Davies & Irwin Inc.

It's no secret that laboratory facilities carry the burden of a large energy demand. Reasons for this high demand include the significant plug loads of specialized laboratory equipment, the high ventilation air change rates that can be implemented in laboratory spaces, and the large volumes of hazardous exhaust air that must be moved out of the building.

Of course, proper equipment and adequate ventilation in laboratories is essential for the success, health and safety of the building and its users. However, no less important is the safe release of hazardous exhaust air from the building such that it does not adversely impinge on nearby air-sensitive locations or the lab building itself via reingestion into air intakes.

Many laboratories have addressed this concern by situating manifolded exhaust fans on the building roof, which is an excellent design step. However, the optimum fan design that harmonizes safety with fan energy and cost is less straightforward, given the many factors that contribute to the best possible dispersion of hazardous exhaust. Such factors include the exhaust plume momentum, the specific fan selection, the discharge location, and the geometry of the buildings in the vicinity.

Wind tunnel dispersion modeling is one means of navigating these many factors to determine the optimal fan design for any laboratory. In particular, this type of modeling is well suited to account for the significant impacts that surrounding buildings and local terrain can have on plume dispersion. These impacts are often more challenging to properly address using numerical analysis methods alone. Wind tunnel dispersion modeling can also be used to quantify fan energy savings by demonstrating what level of fan turndown can be pursued while still meeting applicable health thresholds.

This presentation will provide a prescriptive guide to successful laboratory exhaust fan design for several scenarios that can be encountered at laboratory facilities. The guidance will draw from several wind tunnel dispersion modeling case studies that have evaluated solutions to problematic exhaust situations. The options presented will serve as a useful toolkit for a successful lab exhaust design that satisfies the needs of building users and owners.

Learning Objectives

• Participants will acquire an understanding of the factors that contribute to good laboratory exhaust fan design.
• Participants will acquire an understanding of how wind tunnel dispersion modeling can be a useful tool in the lab design process.
• Participants will acquire an understanding of how energy savings can be achieved with good laboratory exhaust design.

Biography:

Mark is a senior project engineer with RWDI. He has provided consulting services on exhaust and intake designs for a variety of new and existing laboratory facilities in the educational, medical and research sectors. Mark looks to provide advice on designs that can maximize energy efficiency without compromising safety or comfort. Mark is a registered professional engineer in the Province of Ontario and is also a LEED Accredited Professional.

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