Facing the challenges of mixed-use buildings: electrical/lighting/power and fire/life safety
Fulfilling the demands of a mixed-use facility can be challenging, considering the structure’s diverse components. Here, professionals with experience on such projects share advice and explain how to end up with positive results for specialty buildings and electrical, lighting, power, and fire/life safety.
Dave Crutchfield, PE, LEED AP Principal, RMF Engineering, Charleston, S.C.
Julianne Laue, PE, LEED AP BD+C, BEMP, Senior Energy Engineer, Center for Energy Performance, M.A. Mortenson Co., Minneapolis
Robert Nixdorf, PE, LEED AP, Vice President, WSP | Parsons Brinckerhoff, San Francisco
Rodney V. Oathout, PE, LEED AP, Energy + Engineering Leader, Principal, DLR Group, Overland Park, Kan.
CSE: Describe a recent electrical/power system challenge you encountered when working on a specialized building.
Nixdorf: In working with a sports facility, the critical function of the electrical system is reliability. The last thing you want is an outage that causes cancellation or postponement of a televised event. In an ideal situation, you are able to get multiple feeds from different utility substations, decreasing the likelihood of an outage. The load profile of the building is very different from an office building or school, in that the day-to-day demand may be very small (for maintenance or staging). But during an event, you are hitting peak loads that sometimes exceed a utility's ability to carry additional load on a feeder or substation. This can drive up the cost to the owner if the utility has to dedicate capacity.
CSE: What types of smart grid or microgrid capabilities are owners demanding, and how have you served these needs? Are there any issues unique to these specialty projects?
Nixdorf: The demand for photovoltaics (PV) in a sports facility has grown considerably. When you look at the peak demand for a large stadium (generally in the 10-15-MW range during an event), the amount of PV required to meet that demand is not feasible. However, when you consider the overall use of the building over the course of the year, the amount of time spent at peak load is very small by comparison. Suddenly, the limited space available—roof canopies, parking structures, etc.—become useful for PV applications and can produce a higher percentage of the annual usage (kWh). In some cases, utility companies have even sponsored such installations as a mutual benefit for both parties.
CSE: Describe any unusual detection, suppression, and notification systems you've specified in such projects. What drove the design?
Nixdorf: The driving factor for the fire/life safety systems for a sports venue is crowd control. You need to be able to safely evacuate a large number of people very quickly. For this to happen, special steps need to be taken. It is very common in a sporting venue to have delayed notification of a fire during an event. NFPA allows up to 3 minutes from the time the system registers an alarm to broadcast an evacuation notice. This 3-minute window allows security staff to investigate the alarm. The idea is to avoid creating unnecessary panic over a false alarm. In the event of a true emergency, this window allows the public-address announcer to provide evacuation instructions to spectators and give any other necessary information. In this scenario, the fire alarm audible notification would be broadcast over the public address (PA) speakers. Close coordination is necessary to ensure that all PA system equipment carries the proper UL listing for the application and that all communication lines can be properly supervised by the fire alarm system. Smoke control systems have to be designed to consider a fire in the seating bowl or on an adjacent concourse. The goal is to pressurize the spaces to prevent smoke from a fire in the bowl to enter the concourses or vice versa. Sometimes this involves automatically opening exterior doors to allow for proper make-up air. Particularly in the seating bowl, the smoke control system is relied upon as the only means of fire protection. Typically, fire sprinkler systems are not provided in the seating bowl due to their ineffectiveness to cover such a large volume of open space, from 100 ft or more above the floor. Implementing all of these strategies involves close coordination with the project code consultant, the engineers and architects, and, most importantly, the fire department to reach an agreement an acceptable solution.