Good facility planning and the proper solutions for Heating, Ventilation, and Air Conditioning (HVAC) systems credit today's successful forensic facilities. Together they support modern forensic laboratories by providing comfort for lab occupants and an environment that supports scientific investigation.

They are also critical in maintaining a safe and healthy place of business. The control of temperature, humidity, directional air flow, and air quality are necessary performance factors of the forensic facility’s HVAC system. Working hand-in-hand with that is modular planning, flexibility, human centered design, and sustainability. These are performance factors for the planning and design of the facility. All of these factors must be considered when selecting and designing the air supply and exhaust systems, fixed and movable casework systems, building and safety controls, building envelope and structural systems, central heating and cooling equipment, and construction methods and materials that will not harm the environment. In this two-part article, Ken Mohr and Lou Hartman explore ideas and solutions for your engineering and architectural questions.

A key challenge: Forensic laboratories have a wider range of laboratory spaces than any other type of science facility
Avoid cookie-cutter solutions. That is to say that a generically applied solution throughout the forensic laboratory is one of the biggest mistakes you can make. The only thing generic about a forensic facility is the planning module (building block) set forth to assist in the design, system distribution, and future flexibility of the environment. Designing several HVAC system solutions are necessary to support the wide range of laboratory types. An example would be to compare the ventilation system for a Drug Chemistry laboratory to the requirements of a Ballistics Unit. In this example the two are significantly different. In a Drug Chemistry lab you want to provide ample room air changes per hour (6 to 8, very sustainable; 8 to 12, odor is a bigger issue), but at very low velocities, as not to create air currents that would disrupt an examination process. On the flip side of that is the above average room air changes per hour (30 to 50, aiding in containment of lead) with a directional air flow away or downstream of the occupants in the space. We can also see the differences in the physical space and material selection. The Drug Chemistry lab is a large, open work environment with individual workstations designed for evidence examination while flooded with natural light. The Ballistics Unit test range is a long, narrow space without windows, focused lights on targets, and ballistic resent materials.

A starting precept: Identify and understand the hazards presented in each of the laboratory areas
Don’t assume that a forensic laboratory contains only small amounts of chemicals, so if you classify the building as business occupancy, you’ve done your job. A number of forensic laboratory operations involve some physical or health hazards with daily activates. Materials are used or analyzed that are toxic, infectious, flammable, or explosive. The first step in the architectural design or selection of the HVAC systems comes early in the planning process. Here you have the opportunity to learn not only what is used, but how it is used. The “how” can be more important than how much.

A critical factor in the Latent Print lab is to know if “ninhydrin” is a wet or aerosolized process. Aerosolizing the chemical may cause you to develop the space as a Class 1 Division 1 environment under the electrical code for non-sparking electrical devises. This activity should be contained in a chemical fume hood with a flammable storage cabinet under the fume hood. Remember that a chemical fume hood is a device that is 100% exhausted.

At the same time in Forensic Biology they are working with blood products and no one really knows what is contained in the blood. The best device to exam or prep this product for analysis is a biological safety cabinet. This ventilated device protects the user with an air curtain designed to separate the interior of the cabinet from the exterior environment. It also protects the product from contamination in the same way, but also introduces HEPA (high efficiency particulate air) filtered air from above. Finally this device also protects the environment by filtering and cleaning the exhaust air of the cabinet before it re-enters the room. The air filters on these units remove both odor and particulates of biological materials, not intended for chemical use.