Building safe, effective health care facilities: Electrical and power systems
It’s hard to think of an engineering project with higher standards than a hospital or health care facility—successfully designed and installed systems can literally be a matter of life and death. Emergency, standby, and backup power systems are key to these mission critical facilities.
- J. Patrick Banse, PE, LEED AP, Senior Mechanical Engineer, Smith Seckman Reid, Houston
- Daniel L. Doyle, PE, LEED AP O+M, Chairman, Grumman/Butkus Associates, Evanston, Ill.
- Robert Jones Jr., PE, LEED AP, Associate Director of Electrical, JBA Consulting Engineers, Las Vegas
- Craig Kos, PE, LEED AP, Vice President, ESD Inc., Chicago
- Essi Najafi, Senior Vice President/Principal, Global Engineering Solutions, Rockville, Md.
- Paul J. Orzewicz, PE, Mechanical Engineer, Project Manager, RMF Engineering Inc., Baltimore
- David A. Smith, PE, EDAC, Principal, National Director of Health Care, KJWW Engineering Consultants, Madison, Wis.
CSE: Describe some recent electrical/power system challenges you encountered when designing a new building or working in an existing building.
Najafi: In general, working in an existing building presents more difficulties than designing new buildings primarily because of many reasons: undocumented pre-existing conditions, lack of utility spaces, and low ceiling heights. When upgrading the electrical systems, we also have to take into consideration the adequacy of the existing system’s spare capacity and ability to support new systems. On a recent project we completed for the University of Maryland Medical Center, we needed a new 400-amp feeder to provide adequate power for new computed tomography (CT) equipment. During construction, we found out that the panel that was originally designated to handle the new feeder was not adequate. Equipment supported by that panel had been temporarily disconnected the day the readings were taken. As a result, we needed to bring in power from a substation located farther away from the actual project. The challenge was to figure out the distribution in the field without single-line or riser diagram drawings of the existing system.
Kos: One of our hospital clients purchased an existing 200,000-sq-ft speculative office building with the intent to move in clinical services. After reviewing the building infrastructure and the clinical program, we determined that the building required a new HVAC system, a new 24/7 supplemental cooling system, a new water service, a new waste connection to the municipal sewer system, and a new electrical service and distribution. The main driver for the additional electrical service was the desire for an immediate care clinic and an imaging suite, which contained fluoroscopy, MRI, CT, C-arm, bone densitometry, mammography, and ultrasound. The challenge of providing new service gear and metering in an existing building that was built to maximize rentable square footage proved very challenging and required careful coordination with the utility and existing building tenants as well reconfiguration of spaces and repositioning of existing building loads.
Smith: Many older facilities or portions thereof were wired with a single emergency distribution system. Any significant remodel will require those to be broken in life safety, critical, and equipment branches. This cost can be significant. We recommend that all of our clients have a campus MEP master plan to make all of those items known prior to renovation of those areas.
Jones: The VA expansion in North Las Vegas has been very challenging. It involves the relocation of the medium-voltage distribution feeders serving the facility to allow for the expansion to take place. Implementing the relocations has been difficult as it involves understanding of structural footings, mechanical systems, keeping the facility operational, and future planning. As with any facility in existing operation, the last thing the personnel operating the facility want to hear is that there will be a power disruption for a number of hours. Many hours of design were spent on the minimization of these disruptions and how to best implement them without going over the project budget. An additional challenge encountered often is selective coordination for the essential electrical system when connecting to existing building systems. Many existing building electrical systems were not designed for selective coordination. Connecting new distribution components to these existing systems creates the challenge of how to comply with code without replacing a large amount of the distribution system. Generally, there is no clear-cut answer to this issue; at a minimum the issue should be addressed with the owner and the authority having jurisdiction (AHJ) during the design phase.
CSE: What low- and medium-voltage power challenges have you overcome?
Jones: As mentioned previously, disruption of medium-voltage systems can have a wide-ranging effect on the facility, especially when those systems are the essential systems. Finding alternate routes to refeed equipment for shorter disruptions was the main concern, but other concerns included keeping the ability to properly allow for testing in the future of all systems, and routine maintenance, with the knowledge of NFPA 70E requirements and minimization of fault currents to keep maintenance personnel safe. This typically involves multiple switching arrangements from alternate sources, bypass transfer switches, maintenance switches for minimization of fault currents, and numerous short circuit and coordination studies. The older the facility, the more difficult it is to come up with solutions for the client that are cost-effective and still comply with the more recent codes involving selective coordination and arc flash minimization.
CSE: What types of renewable energy systems have you recently specified in one of these projects? This may include photovoltaics, geothermal systems, wind turbines, etc.
Jones: I recently worked on a 3-MW photovoltaic (PV) system for a hospital which has yet to be implemented. Some of the difficulties involved with PV design for these facilities are the structural integrity of the building and loading of the PV cells, the collection systems, routing of the dc to combiners, and implementation into an existing distribution system in accordance with the local utility company requirements.
Najafi: We’ve worked on a variety of different renewable energy systems including PV, solar thermal, geothermal, wind, and biosolids, but for health care facilities, we’ve seen more solar-based technologies applied to support various subsystems/equipment.
CSE: What unique lighting and daylighting requests have you fulfilled in recent hospital projects?
Jones: The difficulty I’ve experienced includes working with architects and interior designers that want a specific aesthetic, but it can’t be implemented because of the control requirements, cost restraints, and lighting levels versus Watts/sq ft requirements of the codes. In some jurisdictions daylighting is now required to be an automatic function and is becoming easier to implement with the standard LED drivers and the ability to include photocells and dimming into the lighting fixture specified.