Canadian Consulting Engineer

ASHRAE issues recommendations following September 11

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has come out with recommenda...

January 18, 2002   Canadian Consulting Engineer

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has come out with recommendations for how to manage building HVAC systems in case they are threatened by biological accidents or terrorist attacks. A packed room of people at ASHRAE’s 2002 Winter Meeting in Atlantic City, New Jersey on January 14 heard from the special Presidential Study Group that had been formed to look at building systems safety following the terrorist attacks in New York and the subsequent Anthrax contamination scares.
The study group has prepared a draft paper called “Risk Management Guidance for Health and Safety under Extraordinary Incidents,” which was handed out at the Atlanta City meeting. It contains a number of recommendations for owners and operators of buildings with large HVAC and life-safety systems, including commercial, institutional, educational buildings and apartment complexes.
Some building owners had reacted to the threats of biological contamination late last year by sealing off outdoor air intakes, which of course had raised alarms in ASHRAE. One of the major thrusts of the report, therefore, is that operators should not make any changes to their building’s air handling systems without getting professional engineering advice and without knowing and understanding what the consequences of any change to the system might be. The report states: “In the event of an incident of chemical, biological or radiological contamination, no action should be taken regarding fan operation unless the effects of the consequential airflow patterns are thoroughly understood.”
Other recommendations include verifying that the air filter efficiency has been upgraded to the highest Minimum Reporting Value (MERV) attainable, and verifying that air intakes are elevated as high as is practical above ground level, out of easy access. At the ASHRAE meeting one of the panelists noted that because of this need to ensure intakes are secure, from now on architects might not be free to locate air intakes in the low-level locations they often prefer.Insofar as fire protection and life safety systems are concerned, the report recommends strategies like shutting down ventilation fans in the affected zones but not in the entire building, and ensuring emergency egress stairwells are pressurized relative to the adjacent fire zone, which could be done by keeping fans running in the remaining zones as people exit into the stairwells, and by having fans in the stairwell that are controlled by the fire detection system.
Some of the most interesting aspects of the report relate to “What Not to Do.” The recommendations in this section suggest that ASHRAE should not upset the apple cart too much in its attempts to respond to September 11. The report says that ASHRAE should not consider changes to building codes to address extraordinary incidents, nor should ASHRAE start recommending any special measures for protecting buildings against extraordinary incidents like terrorism without carefully considering the usual issues of cost, energy consumption, indoor air quality and site adaptability.


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