Early consideration of both the ventilation strategies within the laboratory space, and the dispersion of laboratory exhausts after discharge is critical to provide a high performance laboratory building that successfully implements energy saving design techniques while protecting the building occupants. Energy reducing design techniques that could influence occupant safety include:
- Laboratory ventilation design strategy (ACHs, local capture, etc.)
- low energy use laboratory exhaust fans (variable volume flow and/or low discharge velocity);
- openings in the building envelope (vents, windows, transitional spaces);
- unique rooftop features (PV panels, wind/solar chimneys); and
- other natural ventilation features (wind scoops/towers).
When these concepts are considered late in the laboratory design process, it can be very challenging to optimize these sustainable strategies while ensuring environmental health and safety objectives are met.
It is a common misconception that a higher number of air change rates within a laboratory will provide occupant safety. This presentation will challenge the concept of using air changes as a measure of occupant safety. In addition, it is common to consider the dispersion performance of the laboratory exhausts and the potential for re-entrainment later in the design process after the mechanical design has been significantly developed. However, waiting to evaluate these aspects at a later stage of design, can limit the ability for changes to the exhaust and intake design, and feasible mitigation strategies are limited. In many cases, the mitigation options available at this stage of design will be in direct conflict with the architectural and sustainable goals for the project. Exhaust dispersion issues should be considered in an iterative and interactive manner throughout the design process, and not just as a modeling exercise near the end of the design process.
Considering these issues early in the design process can be critical to the success of strategies like natural ventilation. There may be existing conditions that could compromise the quality of air drawn into the laboratory, and potentially affect the sustainable features of the building (i.e., if natural ventilation openings will be impacted by an existing neighboring emission source). This is often overlooked at the early stages of design because the team members are typically focused on the design of the building itself.
Specific examples and case studies will be used to demonstrate the benefits of considering the details of the internal laboratory ventilation system and exhaust dispersion and potential emission infiltration during the early stages of laboratory design, and how this approach is critical to ensure a laboratory will meet sustainability and energy use goals while satisfying appropriate safety objectives.
- Demonstrate the ability to use means other than Air Change Rates to improve laboratory ventilation and occupant safety.
- Through a detailed discussion of specialized modeling concepts, recognize relationships between:
- local microclimate conditions;
- factors affecting exhaust dispersion; and
- overall building performance.
- Through the design aspects identified and discussed, gain an understanding of specific details that must be considered to push the limits of potential laboratory fan energy reduction safely.
- Understand the influence of sustainable design strategies on exhaust dispersion and building safety.