Laboratory buildings and healthcare facilities with poorly designed ventilation systems can potentially be harmful to research staff, students, visitors, physicians, patients, and research animals in the building as well as in neighboring areas. In classic cases, toxic plumes for a laboratory exhaust stack have found their way to fresh air intakes for the buildings, exposing occupants to high concentrations of harmful substances. In other cases, people on the grounds around a lab or in nearby buildings can be exposed. In the case of healthcare facilities, the exposure is often to people with compromised conditions including children and the elderly.

Sometimes the exposure only results in odors. Odors, in and of themselves, do not pose a serious health threat, but may reveal other problems and are frequently themselves undesirable. Odors in and around a laboratory environment or a healthcare facility may draw unwanted attention from the workers in the lab as well as people walking, working, or living nearby.

Overly conservative designs which may include tall exhaust stacks, high volume exhaust flow, high stack exit velocity, and/or air pollution control equipment can almost certainly prevent these issues. However, any of these solutions can involve considerable costs and/or aesthestic drawbacks. It then becomes very useful to be able to accurately predict the behavior of the plume from the laboratory exhaust stack and this is where the wind tunnel provides the most accurate technology available today. If the designer knows where the plume will go and what concentrations will occur for each set of design choices, he/she can select the most economical and aesthetically pleasing design that will ensure safety for the building's occupants and visitors as well as help optimize the design saving both first costs and operational costs. AAT's wind tunnel study provides this quantitative information about the plumes from each set of design choices.

It is worth noting that Computational Fluid Dynamics (CFD) or other numerical evaluations are not suitable for modeling airflow around the exterior of a building. ASHRAE states that CFD models can "both over- and underpredict concentration levels by orders of magnitude, leading to potentially unsafe designs." (2011 ASHRAE Handbook -- HVAC Applications, Section 45.10)

For those projects targeting LEED or other sustainability goals, the wind tunnel testing may be selected by the design team to satisfy sustainability goals such as the elective Innovation in Design credit from LEED.

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Last updated 1/25/2014

High winds can cause uncomfortable or unsafe conditions for pedestrians and occupants of outside venues such as balconies or seating areas. The introduction of a new building in a site that was previously used for pedestrian activities can become uncomfortable or unsafe after the new addition is completed. Such windy environments can be inadvertently created by seemingly innocuous design features -- funneling and accelerating ambient winds or bringing high winds from above the site down to the ground level. Often, reasonable design changes can effectively mitigate these potentially windy situations.

By measuring the winds around the scale model in AAT's wind tunnel, potentially uncomfortable or unsafe situations can be discovered. Possible mitigation strategies can be tested to determine their effectiveness in reducing the problems.

With the current concern about rising costs of energy and overall sustainability efforts, the potential for decreasing energy consumption from laboratory exhaust fans is receiving increased attention. AAT has developed new and advanced techniques using the wind tunnel to evaluate energy efficient design on both new and existing laboratories while still maintaining a safe environment.
Conservative designs utilized on many existing laboratories built 10 or more years ago provide low hanging fruit for significant exhaust fan energy savings through modifications that are often simple and provide rapid payback periods. More advanced techniques developed by AAT such as wind-responsive design can often provide even greater savings. Implmenting such strategies to modify an existing lab exhaust system and in the design of several new laboratories have been employed throughout the country and have already produced significant energy savings. The University of California recently awarded a "Best Practices" award to UC Irvine for the use of AAT's wind tunnel services on their campus-wide energy reduction studies. Read more at: