Custom Design For Emergency Communication Systems
November 15, 2013
Unlike the fire alarm systems they might run alongside, emergency communication systems don't have prescriptive requirements for components or features. Each emergency communication system should be a built-to-suit creation that fills the particular needs and overcomes the specific challenges of its unique facility.
The design of the emergency communication system is closely tied to the emergency response plan. The latter will uncover and address the risk factors the emergency communication system will have to accommodate. If a facility does not have an emergency response plan in place, NFPA 1600: Standard on Disaster/Emergency Management and Business Continuity Programs, is a good place to start developing one, says Ray Grill, principal with Arup, in the September 2013 issue of Building Operating Management
Though the particulars of emergency communication systems will differ system to system, in general they will feature a head end to control the system and then an assortment of notification appliances, tailored to suit the end audience. These can include speakers, strobes, text displays, and on. Other systems can be integrated into the emergency communication system, so long as they don't interfere with its operation. These can include phone and computer systems, CCTV systems and other building automation systems.
The whole point of an emergency communication system is to convey a message, so a fair bit of consideration has to be given to how easily and well the message is being received by the facility's population. If there are voice messages, can these be heard and understood? We have all experienced a situation where a voice message is loud enough to be heard but ambient noise completely garbles how well the message can be understood. Grill points to Annex D in NFPA 72 for guidance on quantitative measurements for ensuring intelligibility.
Ensuring an alert tone or voice message can be heard is a little more straightforward. A general rule of thumb is that the sound has to be 15dB above ambient sound pressure levels, Grill says. In very loud spaces (more than 105dB) and/or to accommodate the hearing impaired, text and visual alerts can be incorporated into an emergency communication system. Again, considerations of placement come into play.