To save money, designers connected select light switches to a power source for life safety purposes
SmithGroup was tasked with designing the lighting for a laboratory renovation for a major university system located in the Midwest. Because it was a laboratory, target illuminance within the laboratory space was designed around a 50 footcandle (fc) average at the work plane.
Rather than designing separate egress lighting, it was more cost-effective to connect select light fixtures to a life safety power source than to provide separate dedicated emergency lighting fixtures.
Paired alongside the egress lighting circuit was the use of a UL 924, which allows the egress lighting fixtures to be controlled together with the normal lighting fixtures under normal power operations. Upon loss of normal power, the UL 924 devices trigger and override the on/off or dimmed controls that were in effect during the normal power operation.
In addition, the averaged maintained illuminance and the minimum illuminance along the egress pathways during emergency operation exceeded the requirements of International Building Code and NFPA 101: Life Safety Code requirement of 1 fc average and 0.1 fc minimum. The uniformity ratio between the maximum and minimum illuminance values also exceeded the requirement of 40:1.
