HVAC And Chemical/Biological Threats
Some guidelines already exist, particularly for military structures. Documents are also available from the industry's European counterparts, who have more experience in this area.
The most critical information needed for system designers, most agreed, is risk assessment levels for various types of buildings. Hospitals, schools, and public event facilities (arenas, etc.) are likely high-risk targets in the commercial-industrial sector. How do you help building owners plan for possible events if their structure is down the street from a high-risk target?
According to one consulting engineer, the ASHRAE Presidential Ad Hoc Committee document (at www.ashrae.org) "offers a creditable starting point risk management technique."
"One of the most difficult things is to assess risk, then define the event," stated a member of the military community. The private sector may see regulations in the future regarding response time and risks, like those utilities and the military already have in place.
According to one manufacturer, bioaerosol detection equipment is being developed to lessen false alarm risks. Procedures also are being developed on how to respond in the building to an event (evacuate, change air handlers, close or open dampers, etc.).
A major federal antiterrorist project should help determine how to modify and adapt the HVAC system in case of an event, using real-time detection and response. "There will be a big demonstration this fall," said an engineer.
"What if a local building is attacked?" asked the moderator. What are the strategies for internal or external chemical releases?
"How do we move people from here to there without contaminating everyone in between?" asked an engineer.
"Cleaning levels do exist," replied another. "Hospitals have positive alarm systems and decontamination units outside of the main hospital facility. Transportation can be provided to a prophylactic treatment facility."
"What's going on in antiterrorist protection is virtually nothing except for a few very high-profile buildings," said a mechanical contractor. "If nothing else, find a building and demonstrate what we do already know how to do. Once we do that, we will find acceptance. Incremental improvements will probably add to efficiency and performance."
The largest factor is cost, said an engineer. However, "Most building owners are not going to ask for an assessment because they don't want to know."
How do you get building owners to get an extraordinary event risk assessment without having them run from the potential liability? Most of them don't even want an IAQ assessment, pointed out several participants.
One possibility is to slip it into general operations. Fix underlying problems with the system, including response time and fault notification, and chances are you will help reduce the building's vulnerability. Not having this particular risk management spelled out in the contract isn't necessarily a bad thing for designers and contractors, the forum participants agreed.
Publication date: 02/21/2005