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Your Building's Immune System 101 — From Anthrax to Ebola

Wayne P. Saya, CPE, CPMM  | Published on Friday, July 24, 2015

When it comes to protecting a building's occupants from airborne dangers within the building and from outside which are attempting to come in, your building has an immune system similar to that of your own. Your building has two lines of defense, yet it is the building owner, manager, or facility engineer that determines the strength of that immunity.

The health of your facility's thermal envelope — its skin — its' ability to keep thermal comfort heating and cooling in, and outside air and contaminates out, is measured by the amount of environmental leakage around doors and windows. The lungs of your building — its air handling units — which introduce the regulatory required amount of outside fresh air, is your building's second line of defense.

Ventilation system recommissioning with an added ventilation safety audit is probably the most obvious approach to learning how your facility is performing and how it currently rates. Building envelope air-tightening with building pressurization (more outside air introduced into your building than exhausted) are common practices that are unfortunately not exercised effectively and in most cases inefficiently. The isolation of vulnerable spaces such as lobbies, in a number of cases, are eliminated by value engineering and renovation projects which turn a blind eye to this extremely important building feature.

Within the DC area there are a number of buildings featuring automated heating, ventilating and air-conditioning (HVAC) operational changes in response to contaminant sensing. These exterior wall and roof-top mounted sensors tie directly into your building's automation system, but at an extremely high cost. However, in the alternative, I am familiar with a number of buildings that feature an emergency panic button type of shutdown of their building's air-handling-units upon the detection or notification of an external chemical or biohazard alert.

A review of a facility's outdoor air intake (how your building breathes) audits the safe location (out of sight out of reach) of your building's air supply and the concern of a potential introduction of contaminated air coming into your building. Conversely, what happens if such airborne contaminate reaches your air-handing-unit?

Enhanced particle filtration is the most popular when you select your filter using the Minimum Efficiency Reporting Value (MERV) rating system, or the High-Efficiency Particulate Air (HEPA) for filter selection. It is MERV or HEPA that will advise you which filter product-rating is most effective in keeping out the chemical or biological bad stuff.

As an example and at the time of this writing, the Ebola virus is not an airborne disease here in the US, but there are a number of airborne viruses and bacterial germs, such as the legionella bacteria, anthrax, and others, that can become airborne by negligence, intentional application, or otherwise. But if there is an upside to this danger, because a virus ranges from 0.005 - 0.3 microns in size, and bacteria from .3 to 60 microns, the HEPA filter product is a great way of stopping bad airborne stuff from entering your building.

Now if you want more of a guarantee, than sorbent-based gaseous air cleaning, ultraviolet germicidal irradiation, or photocatalytic oxidative air cleaning, in conjunction with your HEPA filtration, can keep your building or workplace environment isolated from these airborne dangers, until someone has time to push the wall-mounted emergency stop button for your air-handling units.

The cover article of the next AFE Journal will feature a how-to on retrofit options for your facility against internal and external airborne chemical and biological releases and hazards. Meanwhile, because each building has its own personality, I would suggest you consider speaking with your Certified Air Filtration Specialist (CAFS), certified by the National Air Filtration Association (NAFA), for the best professional advice.