DOB Findings and Recommendations for WTC, Feb 2003

NYC 9/11 Public Portal Document

4.4:2 Elevators i 1

Water damage to elevators and elevators with advanced controls were discussed by the Mechanical Working Group.

The predominant reasons elevators are not usable during erhergencies are power failure and damage due to water. Their mechanical systems are often times shut down by water that penetrates elevator shafts. To encourage the development and use of drainage systems to catch H sprinkler and fire hose runoff in elevator shafts and near elevators, the Task Force recommends excluding components of these systems from being counted as "fixture units."

The mechanical group reviewed ways in which elevator controls could be engineered for more effective use in emergency situations. However, much like the evacuation group's discussion of "Phase HI" elevators, the emerging technology is still at the research and development stage. No satisfactory conclusions could be made.

Recommendation 17. Exclude floor drains for elevator vestibule and shafts from being counted I as fixtures in calculating normal waste water pipe capacity. I t

4.4.3 Heating, Ventilation and Air Conditioning (HVAC) Due to heightened security concerns, or the increased likelihood of an attack on building occupants through the use of HVAC systems, the mechanical group decided that even though air intakes for these systems are typically located above grade, that a standard should be set to require this practice. It was determined that air intakes should be located at least 20' above grade t. in all new construction and not in proximity to exhaust discharges of off street loading bays. 1 I HVAC systems can be designed to serve entire buildings or individual tenant spaces. Both design approaches are currently used in New York City and are allowed under current Building Code. The Mechanical Systems Working Group discussed, at the suggestion of FDNY representatives, the issue of fire spreading through a system's ductwork. It was pointed out that individually planned systems rely less heavily on ducts passing through other tenant occupied spaces than do centrally planned systems, theoretically lessening the spread of fire. The group agreed that only allowing the use of individually planned systems, which would not be economically viable, was not appropriate. It did suggest making the inspection of fire dampers a controlled inspection item, to enhance the enforcement of the current code. I \ No recommendations were made regarding the use of HVAC systems to defend against biological-chemical attack due to the lack of practical, cost effective systems at this time. ! ! Recommendation 18. Require air intakes in all new construction to be located at least 20' above grade and away from exhaust discharges or off street loading bays. I 19. Require controlled inspections of HVAC fire dampers in newly constructed I I occupancy group E buildings.

1 I Page 26 WTC Building Code Task Force February 2003 Findings and Recommendations

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