Section 270.100 - General(a) Based on prior NIST experience, NIST expects that the Director will establish and deploy a Team to conduct an investigation at a frequency of approximately once per year or less.(b) For purposes of this part, a building failure may involve one or more of the following: structural system, fire protection (active or passive) system, air-handling system, and building control system. Teams established under the Act and this part will investigate these technical causes of building failures and will also investigate the technical aspects of evacuation and emergency response procedures, including multiple-occupant behavior or evacuation (egress or access) system, emergency response system, and emergency communication system.(c) For purposes of this part, the number of fatalities considered to be "substantial" will depend on the nature of the event, its impact, its unusual or unforeseen character, historical norms, and other pertinent factors. 68 FR 66704 , Nov. 28, 2003, as amended at 69 FR 33571 , June 16, 2004