Fortifying Building HVAC Systems Against Terrorist Attacks

Years ago, I learned of a technology that not only can protect building occupants from a chemical, biological, or radiological attack, but limit the property owner’s liability, too.

Larry Clark

May 12, 2015

3 min read

How many of us have seen a fresh-air inlet located downwind of a bus stop, where buses routinely idle their engines?

In the past, such design blunders were annoying, but—thanks to dilution—generally not life-threatening. Today, however, that scenario for a high-rise office building could be disastrous. What if, instead of low levels of carbon monoxide from idling buses entering the building, a terrorist (or criminal driven by non-political motives) released chlorine gas or Cesium-137—used in a variety of medical and industrial applications and believed by many experts to be the most likely radioactive element in a dirty bomb—into an outside-air intake or interior return-air intake

Buildings considered by experts to be the most vulnerable to this type of attack include those that are nationally identifiable; have high occupant densities and, thus, would be difficult to evacuate quickly (which includes most urban high-rises); are critical to the local, regional, and/or national economy; or are in close proximity to other high-risk buildings. Facilities close to rail lines or a vehicular tunnel or adjacent to a significant transportation hub or bridge entrance also are particularly at risk, as are buildings located close to critical infrastructure or those that house or use potentially harmful chemical, radiological, and/or biological materials.

Several years ago, I became aware of a technology that not only can protect the occupants of a building from a chemical, biological, or radiological attack, but—as a SAFETY Act (Subtitle G of Title VIII of the Homeland Security Act of 2002) Designated Qualified Anti-Terrorism Technology—limit the property owner’s liability if such an attack were to occur.

Although the technology is relatively sophisticated, the basic theory of operation is not: A sensor array capable of detecting an event in milliseconds strategically located in supply- and return-air ducts automatically directs a building-management system to immediately shut down a building’s air-distribution system in the event of an incident. After isolating the toxin, the system calls first responders and provides real-time substance data and location information.

Today, with counterterrorism experts calling office buildings ideal targets for terrorists and frequently identifying the HVAC system as the most likely distribution point for a toxic attack, why haven’t more building owners/managers availed themselves of this protection?

Although these systems are not inexpensive, the one with which I’m familiar, Building Protection Systems’, is reasonably priced. Compared with the death, serious injury, and enormous property damage that can result from such an attack, it seems to me to be low-cost protection.

Terror attacks are never a pleasant topic of conversation, but in our post-9/11 world, they are a reality that must be addressed. It’s time for owners, designers, and consultants involved with vulnerable buildings to start having some serious dialogue. You can be sure my clients and I are having that conversation.

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About the Author

Larry Clark

A member of HPAC Engineering’s Editorial Advisory Board, Lawrence (Larry) Clark, QCxP, GGP, LEED AP+, is principal of Sustainable Performance Solutions LLC, a South Florida-based engineering firm focused on energy and sustainability consulting. He has more than two dozen published articles on HVAC- and energy-related topics to his credit and frequently lectures on green-building best practices, central-energy-plant optimization, and demand-controlled ventilation.