Enhancing learning in K-12 schools: Electrical systems
Students and teachers benefit from many electrical engineering technologies in K-12 schools
Doug Everhart, PE, LEEP AP, K-12 education practice director|principal, Henderson Engineers, Lenexa, Kansas
Keith Hammelman, PE, principal, CannonDesign, Chicago
Brian A. Hummel, PE, LEED AP BD+C, mechanical engineer, senior associate, DLR Group, Phoenix
Richard Sparozic, PE, mechanical engineer, Kohler Ronan Consulting Engineers, Danbury, Conn.
Casimir Zalewski, PE, LEED AP, CPD, principal, Stantec, Berkley, Mich.
Are there any issues unique to designing electrical/power systems for these types of facilities?
Doug Everhart: Many of our electrical systems are designed with the architecture of the power distribution system setup to isolate and submeter HVAC, lighting and kitchen loads in schools. This allows for better information when trending energy within a school and can help pinpoint where controls optimization and better performance is needed. These submeters can tie to the building automation system for trending and control. Oftentimes we will use this data to display for a building dashboard or to become part of engineering or building system technology curriculum so that students are seeing and participating in the overall performance.
Richard Sparozic: Net zero energy buildings are becoming more common. Because of this, the mechanical, electrical and plumbing equipment is all electric and increases the size of the electric service. Photovoltaic arrays are provided to offset the purchasing of electricity from the utility company. This analysis is performed on an annual basis so, during the winter months, the PV array may not be offsetting the electrical consumption, but, in the summertime, this will be made up or exceeded such that over the entire year there is net-zero consumption from the utility company. Space proofing for the PV inverters must be accounted for and the disconnect switch located near the front entrance where first responders can disconnect the PV array from the building for safety purposes.
What types of unusual standby, emergency or backup power systems have you specified for K-12 school buildings?
Richard Sparozic: Often schools are used as cooling or warming centers when there are large power outages and the population is looking for a hot meal, shower and charging area for their electronic devices. Therefore, in addition to the traditional emergency lighting, life safety loads and the kitchen refrigeration standby loads, other electrical loads must be considered.
Generally, the owner will program the gymnasium, cafeteria and locker rooms for areas to be occupied as a shelter for the community. The HVAC and domestic hot water equipment that serves these areas will need to be connected to a dedicated standby automatic transfer switch for showering and food preparation. The ability for the gymnasium and cafeteria to be flexible regarding the use of program space so that they can accommodates both school functions/activities as well as emergency shelter occupancy is very important.
What are some of the challenges when designing high-voltage power systems in K-12 school projects?
Doug Everhart: Distributing medium-voltage systems such as 5 and 12 kilovolts on large K-12 campuses can be beneficial as it can allow for smaller duct banks, smaller distribution cabling (and thus less copper), lower voltage drop and power loss and future expandability. However, it can also come with many challenges such as:
- Medium-voltage substations, switchgear and transformers that demand larger outdoor electrical enclosures, larger indoor electrical rooms, higher enclosure fire ratings and larger clearances that 480- or 208-volt equipment.
- K-12 district maintenance staff is not always trained or provided the proper personal protective equipment to work on switchgear above 480 volts. This requires the district to hire specialty electricians certified to work on medium-voltage equipment.
- Cost of medium-voltage equipment tends to be more expensive due to additional level of relays, switches and protection within the equipment.
Richard Sparozic: Traditionally, there are not many high-voltage systems in a K-12 school. The utility company will provide a single step-down transformer and the building will use 480- or 208-volt systems.
What kind of maintenance guidelines are involved to ensure the project is running efficiently after the project is finished?
Richard Sparozic: Provisions can be included in the design documents requiring that the different vendors provide recalibrating services and record any operation issues the owner may have had throughout the year. Retraining is also included in the design documents to help facility personnel become familiar with technologies that they may have never used before.
Keith Hammelman: This ultimately comes down to working with the client during the specification of the new equipment to ensure that they fully understand the design intent and have input into the design. Also, during the installation and commissioning it is important to have the client’s maintenance staff there to ask questions so that they are can better understand the functionality of the systems. After the installation is complete of the systems, we do like to see an owner employ a continuous commissioning system to alert them to operational issues, which may decrease the efficiency of the facility.
Doug Everhart: There are a multitude of factors that are involved with ensuring a building is maintained properly and operating efficiently through its life. Simple things like periodic filter and belt changes, verifying proper operating schedules and temperature setpoints, are some of biggest opportunities for energy reduction and should be continuously monitored. For buildings that are experiencing diminishing energy performance we recommend existing building commissioning to thoroughly investigate the root cause of the problems and identify cost effective solutions. Commissioning agents can also assist with cataloging equipment and developing operation and maintenance plans to be carried out by facility maintenance staff or hired service contractors.
What are some key differences in electrical, lighting and power systems you might incorporate in this kind of facility, compared to other projects?
Keith Hammelman: Dynamic, tunable white lighting is now on the scene, which can assist with circadian entrainment. The premise is well-entrained circadian systems allow occupants to be more alert and focused in learning environments. Natural light is the best lighting for our circadian systems, but electric lighting that can mimic the cycle of blue rich light at the right times of day can similarly mimic the positive effects of daylight.
Doug Everhart: The wide variety of space types found in K-12 projects continues to challenge designers in bringing innovative ideas to bear. Classrooms, STEM labs and maker spaces, athletics, performing arts centers and special needs learning areas all require unique approaches to designing lighting and power systems. Dimming and daylight harvesting are now nearly universal and incorporating audiovisual switched zones of light fixtures is becoming less common due to brighter flat panel displays versus older projector systems.
On recent early child care projects, large 4- by 4-foot recessed LED fixtures with completely uniform light output across the face of the luminaire, coupled with tunable white controls give students with special needs much more flexible and comfortable classroom lighting systems. In maker spaces, overhead track systems are home to cord reel receptacles to give young creators even more flexibility in how they use their STEM classrooms.
Richard Sparozic: To make sure that lighting levels are adequate for all ages and that rooms are very flexible, lighting controls require multiscene controls.
How does your team work with the architect, owner’s rep and other project team members so the electrical/power systems are flexible and sustainable?
Doug Everhart: We find that focused meetings with the specific teachers, administrators and students helps us properly plan the systems that will support equipment and specific uses. Every space is different so we make it a common practice to conduct meetings with the proper stakeholders present early on in any project.
Richard Sparozic: This topic should be heavily discussed in the schematic design phase. Unfortunately, it is often overlooked then since this phase is primarily for determining pricing. The reason it should be discussed early, however, is that the owner may require time to gather input from different end-user departments before finalizing requirements.
Keith Hammelman: We try to talk early about current and future use cases, introduce technologies that support their goals and discuss futureproofing needs. We always try to design with energy efficiency and flexibility in mind and think about what might be coming down the road. Things like innate dimming for the LED fixtures we specify and designing around wireless control systems that make reconfiguration easy are ways we can be thinking about flexibility and sustainability.
What kind of lighting designs have you incorporated into a K-12 school project, either for energy efficiency or to increase the occupant’s experience?
Richard Sparozic: LED lighting is the efficient choice for lighting source. Switching lighting is the key to energy savings, maintenance of proper lighting levels and the creation of the optimal student learning environment. Classrooms are switched such that the lighting fixtures located in the daylight zone are automatically balanced against natural sunlight. In this way, students experience the same light level, but the use of the daylight is optimized so students feel more connected to nature and thus are likely to be more productive. The artificial lighting is also switched such that the first 25% of the room, from the teaching wall, can be switched off for better visibility of a presentation while the remainder of the room remains lit so the students can take notes without straining their eyes.
Keith Hammelman: LEDs have taken over, especially now tunable white is on the scene. We are seeing clients asking more and more for information on these systems and how they can improve education outcomes. Simple controls are needed for these to work — automation is key for circadian systems — and luckily control manufacturers are coming to the table with solutions to these design challenges.
Doug Everhart: In most projects we are designing 100% LED-based systems. LED allows for better efficiency, longer life and enhanced controllability. Additionally, customizing the lighting and flexible power systems specific to these space types and the use of them are a key in proper design. For classrooms, we typically design local manual/dimming control for lighting systems while integrating automatic daylight harvesting and occupancy sensor automatic shut-off for increased energy efficiency. The lighting zones are also programmed with the capability to adapt to the various modes of the classroom — AV mode, energy savings mode, test taking mode, etc.
When designing lighting systems for these types of structures, what design factors are being requested? Are there any particular technical advantages that are or need to be considered?
Keith Hammelman: We try to deliver as much daylight as possible, then coordinate the lighting system to integrate and augment available daylight. Flexibility, ease of use, ease of maintenance and energy efficiency are usually the top client requests.
Richard Sparozic: It is necessary balance the owner’s specific requests regarding lighting operations versus applicable code requirements and maintenance operations. We have incorporated bypass switches to energize site lighting to facilitate repair/maintenance work during normal hours rather than on premium time. Corridor lighting is turned on during business hours by the building management system; outside business hours, it is operated by occupancy sensors whereby lighting is only energized where it is needed. Discussions with the local fire marshal are also suggested to determine how far from the building they require emergency lighting to be provided. Having early discussions on these topics ensures that all the design members are on the same page.