How to design electrical systems in government buildings
In this Q&A with multiple experts, learn how to design electrical and power systems in government, state, municipal, federal, correctional and military buildings
- Steve C. Davis, PE, electrical discipline lead, LEO A DALY, Atlanta
- Raymond Krick III, PE, CxA, LEED AP, project manager, RMF Engineering Inc., Baltimore
- Allen Poppe, PE, principal mechanical engineer, Stanley Consultants, Muscatine, Iowa
- Andrew Stanton, PE, mechanical engineer | senior associate, DLR Group, Cleveland.
What types of unusual standby, emergency or backup power systems have you specified for such facilities?
Steve C. Davis: We recently had a project that had two existing generators that were installed at the same time only a few years before the start of our project. Since the generators were fairly new (about five years old) the government wanted to continue using them, if feasible. They were identical generators in that they were made by the same manufacturer and had the same electrical characteristics, but they independently served two separate buildings. The new design relocated the generators and connected them in parallel to new essential main distribution switchgear by using modern independent onboard paralleling controls. This arrangement provided improved reliability and redundancy for serving the full normal power demand of the facility. Each generator had a new factory-fabricated sub-base diesel fuel tank installed under them. Fuel filtration equipment was provided for each sub-base fuel tank to ensure quality fuel requirements were met for serving the generators.
The site for this project was very congested and the topography had extreme ranges in elevation, making it difficult to co-locate the generators. An existing service driveway had a steep embankment to one side that was cut back for the installation of a modular block retaining wall. This enabled the installation of a concrete equipment pad large enough for installation of the two generators.
What are some of the challenges when designing electrical, power and lighting for government, state, federal, correctional and military projects?
Steve C. Davis: Until recently, lighting design in military medical facilities was quite a challenge. The government criteria that addressed lighting design was not up to date, in that it only allowed fluorescent lighting sources. It took some time to update the criteria to allow the use of LED lighting. This is an example of where the technology was growing faster than the criteria that governs the installation could keep up.
“Resilient” or “resiliency” is a buzzword when discussing government buildings. What are owners requesting to make the building meet resiliency goals? How are you these buildings to be more resilient?
Steve C. Davis: This often depends on the type of project and where it is located. If the project is in high seismic zone, the electrical equipment will require proper seismic bracing to maintain operation during a possible event. For a hospital or research laboratory, the normal power system will typically have two diverse primary utility feeds; if one feed fails, the other feed would continue to carry the load. If both normal feeds go offline, then there is an alternate power source that would typically carry the essential load of the facility. In some cases, the alternate power source may carry the entire demand load.
Allen Poppe: Resiliency including energy and water efficiency is regularly included. Renewable energy is a little less common. Solar thermal water heating is evaluated. Solar photovoltaic is occasionally implemented at the building level for our Department of Defense clients.
Describe a government project with a high power load, such as a data center or research facility. What did it include and what best practices did you include for these facilities?
Steve C. Davis: The Armed Forces Radiobiology Research Institute’s is a government lab campus devoted to developing drugs to prevent the life threatening and health degrading effects of ionizing radiation. Buildings 43 and 47 serve as the vivarium for the Institute. Both buildings 43 and 47 are more than 30 years old with failing infrastructure and functional problems. Lab facilities are among the most power-hungry facility types. As part of this renovation, all of the utilities throughout buildings 43 and 47 will be replaced. There will be a new double-ended secondary unit substation with interior network service transformers and normal power distribution switchgear. There are two existing emergency generators that will be relocated so that they are adjacent to each other. The generators will be connected in parallel to new essential main distribution switchgear; this arrangement will provide improved reliability and redundancy for serving the full normal power demand.
Are you seeing more smart- or microgrid aspects on such projects? If so, how have you served these needs?
Steve C. Davis: We recently designed a laboratory facility that used two spot network type transformers, similar to the types the utility companies use. The normal power system modifications included two new medium-voltage service feeders fed from an existing NAVFAC owned and maintained primary unit substation. These feeders served a double-ended secondary unit substation that consisted of two equally sized oil-filled network service transformers. The secondary side of each transformer was connected to a common bus through network protectors and a normally closed tie circuit breaker. This network arrangement provides 100% redundancy of the loads served in the event that if one of the transformers or primary feeders should fail, the other transformer and primary feeder will automatically carry the full demand load without an interruption of power.
What kind of lighting designs have you incorporated into such a project, either for energy efficiency or to increase the occupant’s experience?
Steve C. Davis: Our projects are mostly designed with LED light sources. We had one project that was designed using fluorescent under older UFC guidance. By the time the contract was awarded and under construction this UFC had changed to allow the use of LED. During construction and before release of the fluorescent lighting fixture, the design was changed to LED. The specified fluorescent fixtures were not readily available and it was less expensive to order them as LED. Not only did this bring the facility up to current standards, it allowed for the use of newer technology. We were able to select LED fixtures with the same or better lumen output than the fluorescent fixtures, which allowed for the layout to remain unchanged. The lighting power density decreased approximately 50% to 60% by making this change.
In the same project, lighting in the vivarium areas were designed in accordance with the Guide for the Care and Use of Laboratory Animals published by the Association for Assessment and Accreditation of Laboratory Animal Care International. The animal holding rooms were designed with a central automated lighting control system for monitoring and regulation of diurnal and circadian cycles, as well as control of lighting levels. The lighting had automatic dimming controls to simulate a diurnal cycle for most animal species. Independently controlled red lighting was used in the animal holding rooms, in addition to the general room lighting. Red lighting is used in animal research laboratories so that it does not disrupt the sleep cycle of nocturnal animals, while lab technicians are free to continue their research.