Perhaps the most critical pieces of advice offered by mechanical engineers to building owners and managers fearful of attacks on their properties is what not to do, rather than what to do. Beware of opportunists: "Do not close outdoor air intake dampers or otherwise block ventilation paths; do not change the designed airflow patterns or quantities; and do not modify the fire protection and life safety systems without approval of the local fire marshal."
So says the American Society of Heating, Refrigerating and Air-Conditioning Engineers Inc. in an eight-page "initial" report issued last week. Risk Management Guidance for Health and Safety Under Extraordinary Incidents also offers guidance on steps that can be taken to render buildings somewhat less vulnerable to bioterrorism and other attacks. But for the time being, unless the building is an obvious target, ASHRAE recommends operating buildings normally and, in every case, not making any changes without consulting a professional engineer or system expert. "We have to take time to figure out if [owners] need to do anything different to operate their buildings as safely as possible in the event of another incident," said William J. Coad, ASHRAE president, at the Jan. 12-16 winter meeting in Atlantic City, N.J.
|SMART WALLS Wedge work (above left) includes horizontal walls with all utilities (above) that speed tenant fit-out. (Photos courtesy of the Pentagon Renovation Program)|
"We don't want to tell anyone anything that can be misunderstood and misused and don't want others to do the same," said Coad, senior principal of McClure Engineering Associates, St. Louis. And "we don't want to give people the impression that we can make buildings safe" from attack.
The report, written by a 10-person committee, is not a "definitive piece" and not based on a specific building or HVAC system, said James E. Woods, committee chair and president of HP Woods Research Institute, Herndon, Va. It does advise owners to get to know their buildings before making changes and to develop a preparedness plan in case of an incident. It is important to look at the building operation as a whole and to avoid measures that can backfire, caution the authors. For instance, closing off air intake vents can decrease a system's ability to purge contaminants.
Sensors and other warning devices are not available or are not reliable for many contaminants so they cannot be used as a control strategy, says the report. For protection against aerosol attacks from outside, openings "must be capable of timely closure, located sufficiently remote from any launch site or the building must be equipped with adequate filtration."
|SCHEDULING Trades will work unimpeded by others. (Photo courtesy of the Pentagon Renovation Program)|
Areas of refuge are not economically viable in many buildings. Consequently, HVAC systems can be used to pressurize building egress paths and to isolate significant contamination to "selected building volumes," says the report. Finally, enhanced air filtration alone is not sufficient to reduce airborne contamination. It should be coupled with pressurization of the interior relative to the outdoors.
During a comment period at the Jan. 14 forum held to introduce the report, a lapsed member of the committee issued a protest. "I don't believe it is appropriate to do this in a public forum," said Michael Dillon, a Long Beach, Calif., consulting engineer. "It should be done in executive session. We should not be giving anyone a road map to bring us down."Others disagreed, saying those who want to do harm have better ways to get information they need.
Coad says the next step is to disseminate the report to building owners and managers and to initiate a year-long exercise to produce more specific guidance. ASHRAE also intends to coordinate its efforts with other engineering disciplines engaged in parallel studies.