Since crime lab design is one of the focuses of this issue, we saw an opportunity to champion indoor environmental quality. During our years of involvement with new construction projects we have seen complaints and problems surface after occupants have moved in. Even though Environmental Health and Safety was plugged in to the design review and dutifully examined and signed off on construction specifications, important considerations were overlooked. Sometimes it showed up immediately after occupancy, such as excessive room noise from the ventilation system. More often it would be delayed until transient smells or nuisance odors were repeatedly drawn into the building. And a few took much longer, maybe years, until the black particles began pouring from the supply vents. But all of these issues affect indoor environmental quality (IEQ) and thus employee comfort, productivity, and possibly health. The good news is most of these conditions are preventable.
The following recommendations have been culled from years of dealing with IEQ complaints. Often the fix is very simple and costs almost nothing. More often than not, the problem is traced back to poor design and ends up costing lots of money for renovations not to mention the disruption to normal operations. If you can catch any of these during design it can save immense sums down the road.We would strongly recommend that you develop an IEQ design policy and make sure all architects and engineers receive a copy when beginning a project.
First and foremost you want to ensure the ventilation systems are generally consistent with all appropriate recommendations of the latest version of the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) Standard 62, Ventilation for Acceptable Indoor Air Quality.1 Isolate all areas utilized for containment and any odor or contaminate generating activities from the return air system and ensure adequate exhaust air is provided. Examples include laboratories, lavatories, autoclave rooms, chemical storage areas, kitchens, and document printing, copying, and reproduction. Maintain laboratories and other such areas at a slight negative pressure with respect to surrounding office and reception areas. In other words, slightly more air is exhausted from these spaces than is supplied to ensure contaminates or odors do not migrate into surrounding areas. In addition, the overall building pressure differential should remain slightly positive in relation to the outside atmosphere.
If local exhaust ventilation (LEV) systems are used, such as specialized hoods or snorkel systems, their design should follow the most recent version of the American Conference of Governmental Industrial Hygienists (ACGIH) Industrial Ventilation, a Manual of Recommended Practice.2 Pay special attention to the exhaust stack discharge design and proper height when evaluating the LEV system.