Share thisThe Safety Guys decided it was a good time to provide our design tips for indoor environmental quality.
In recent years a few new buildings have come back to haunt us 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 being overlooked and conditions for the actual occupants turned out not as we expected or anticipated. In some cases immediately after occupancy, an issue would turn up, such as room noise from the ventilation system. Often a problem wasn’t discovered until sometime later when transient smells or nuisance odors were repeatedly drawn into the building. And a few took problems took much longer, maybe years, to present themselves, as in black particles pouring from the supply vents. But all of these affect indoor environmental quality (IEQ) and thus employee comfort, productivity, and possibly health. Further, 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. However, 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.
Ventilation System
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, animal housing areas, kitchens, and document printing areas. Maintain vivariums, 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 Remember to include the exhaust stack discharge design and proper height when evaluating the LEV system.
Finally, consider the maintenance personnel and require proper roof access provided by adequate openings with stairs and not ladders, not even fixed ladder systems. It is not easy to climb vertically with a heavy tool belt and hands full of spare parts.
Duct Systems
One of the most important (and potentially troublesome) components is the system of ducts that move the ventilation around the facility. Nine times out of ten, the black particles pouring from supply vents mentioned earlier is due to internally insulated duct eroding over time. Therefore, all ductwork associated with the HVAC systems supply and return air distribution as well as outside air intakes (more on these later) must not have internal lining or insulation.We highly recommend only metal ducts in industrial settings, ductboard is just not acceptable. Construct all ducts so that they are effectively sealed.