Cleanrooms and High Performance Labs – Understanding the Dispersion and Potential Impact of Chemical Emissions to Explore Energy Savings

Aimee Smith, RWDI

Cleanrooms and other high performance research labs are unique facilities geared toward research at the nanoscale in a wide range of areas including microelectronics, molecular engineering, medical technologies, nanofabrication, energy efficiency and storage. Many of the processes necessary for this research involve the use of hazardous chemicals and toxic gases. The emissions from these processes result in a specialized laboratory exhaust that can be challenging to address from both design and operational energy savings perspectives.

The emissions from these unique processes are often treated with point-of-use abatement and discharged using significant air quantities. In some cases - such as in the use of large quantities of solvents in wet bench activities for microelectronics research - there may also be a need for additional abatement at the point of discharge to further reduce these emissions. A thorough understanding of the chemical emissions profile and the dispersion levels from these exhausts can be a useful tool for designers and owners to determine the required efficiency level for any abatement equipment, and opportunity for fan energy savings.

The expected chemical emissions profile can often be provided by a Cleanroom consultant. For existing Cleanroom retrofits or expansions, it may be necessary to estimate the emissions based on the activities and equipment in the existing labs. This information can then be used in tandem with exhaust dispersion modeling to predict the chemical concentration levels expected at sensitive receptors following stack discharge. Predicting the behavior of the exhaust from the chemical processes can be accomplished using either numerical or physical (i.e., wind tunnel) dispersion modeling techniques. Ultimately, the selection of the most appropriate model will depend on the site, the building and roof geometry and the equipment specifications. In many cases, the use of wind tunnel modeling can be advantageous as it allows for the combination of detailed dispersion data with local historical meteorology to quantify the level of risk.

This presentation will draw on experience with several Cleanroom projects to illustrate how dispersion modeling can be used effectively to understand the dispersion and potential risk from these chemical emissions, to optimize the required efficiency of the abatement equipment, and to identify opportunities for fan energy savings.

Learning Objectives

• Through the design aspects identified and discussed in the presentation, participants will gain an understanding of the potential challenges associated with the chemical emissions from Cleanroom and other High Performance Lab exhausts.
• Through a detailed discussion of specialized modeling concepts, participants will be able to recognize the relationship between building design, use of abatement controls, and exhaust dispersion levels
• Participants will be equipped with a tangible methodology for evaluating the risk from these chemical emissions and solution strategies and design concepts to address safety without overdesigning and allowing for fan energy savings.

Biography:

Aimée Smith is a Principal of Rowan Williams Davies & Irwin Inc. (RWDI) in Guelph, Ontario, Canada and a Project Director in RWDI's Building Science division. She is a registered Professional Engineer in the province of Ontario, an I²SL member and a member of Sustainable Labs Canada. Aimée specializes in exhaust dispersion and re-entrainment studies for the design of building exhaust and air intake systems for laboratory, health care and other related facilities.

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