Enhancing learning in K-12 schools with energy-efficiency buildings
Students and teachers benefit from many engineering technologies in K-12 schools, including sustainable building systems
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.
What level of performance are you being asked to achieve, such as WELL Building Standards, U.S. Green Building Council LEED certification, net zero energy, Passive House or other guidelines?
Keith Hammelman: This is all over the map for the certification requirements, but we are seeing a focus on providing facilities that can achieve net zero energy. For our projects in California, we use Collaborative for High Performance Schools and design the facilities to provide the infrastructure for photovoltaic arrays to maintain a net zero energy design. We also use energy modeling at the earliest stages of design to inform the design of the facility to meet these goals with the building orientation, building envelope, lighting design and HVAC system performance.
Casimir Zalewski: Many K-12 schools are interested in the concepts associated with WELL, U.S. Green Building Council LEED, embodied carbon and others. The decisions to design around the concepts and demonstrate to the community that the district is being a good steward is typically more important than the actual certification or certain level. The demonstration of sustainability and follow through in actual operation drive the design.
Brian A. Hummel: We have clients who continue to pursue LEED certifications, but others who are adopting WELL standards more focused on health and well-being. We also recently received certification through the International Living Future Institute for the net zero positive energy building on the West-MEC Southwest campus in Buckeye, Ariz. This certification used 12 months of verified data confirming the building goes beyond the zero-energy level by producing 108% of what it consumes.
Doug Everhart: The main certification system for any districts is LEED. This is a system many understand and may have experience from previous projects of what to expect and how best to achieve their desired performance goals. In California districts are looking for a percentage above code or a CALGreen Tier to help push for more efficient project performance.
What unusual systems or features are being requested to make such projects more energy efficient?
Doug Everhart: Flexible use and co-learning spaces present a challenge and the space controls (lighting and mechanical systems) have to respond to inconsistence or transient use. Lighting systems can turn on when occupants enter, but it is important the lights don’t remain on once all occupants have left. The mechanical systems face an opposite issue where if a space needs to recover from setback there can be a delay in the space’s comfort, but again the system needs to shut off (or standby) when the occupants leave. That inherently makes these spaces difficult to predict and control.
Describe a recent project in which the building envelope was complex or unique.
Richard Sparozic: Our team is currently working on a new high school that is located near the Long Island Sound. The flood plain is relatively low and the salt content in the air from the water is high. With this in mind, we needed to locate equipment at elevations above the proposed 100-year-flood and specify equipment with corrosive coatings.
Doug Everhart: High performance envelope components aren’t just for thermal comfort but also durability. An example is a high school project used insulated concrete sandwich panels, with 4 inches of continuous insulation and not through concrete. This provided a well-insulated envelope with high durability and long life of the structure.
What types of sustainable features or concerns might you encounter for these buildings that you wouldn’t on other projects?
Doug Everhart: The use schedule of many K-12 buildings is different from what one would see in an office building or retail store. The summers are lower occupancy or unoccupied and the days tend to end earlier than either of those other occupancy types. This directly impacts how the mechanical systems operate and even the systems selected for use in schools.
What types of renewable or alternative energy systems have you recently specified to provide power?
Keith Hammelman: We are seeing a focus on the use of photovoltaic arrays to provide renewable energy systems on K-12 buildings. The challenge we are often seeing is providing adequate infrastructure in a new construction project to allow for the future installation as a part of an alternative financing method. This often involves providing structural supports and electrical conduits to predetermined locations within the project site which a future contractor may connect to as a part of power purchase agreement or ESCO project.
Doug Everhart: Photovoltaic is the most common as the systems can be roof or ground mounted and tied to the school’s power systems. In some instances, these also serve as a teaching tool to help students understand renewable energy or even larger full-scale building energy performance.
Casimir Zalewski: It is becoming more common to be requested to study adding photovoltaics to K-12 projects to offset energy usage. The typical challenge is that the roof was not designed to support the array and the roof still requires access for maintenance. The typically solution involves a structural engineer, electrical engineer and architect to develop potential arrays while preserving roof stability, access for maintenance and visual sightlines. Non penetrating mounting details and ballasts are typically developed to prevent the panels from taking flight or damaging the roof.
Richard Sparozic: Kohler Ronan has seen an increase in the number of clients requesting photovoltaic arrays. When thinking about photovoltaic systems, it is always important to consider their orientation to ensure that the maximum solar exposure is achieved. Our engineers recently worked on a project in Greenwich, Conn., in which mechanical equipment mounted on the roof, as well as architectural building features, were creating shadows during the course of the day. A cost benefit analysis for photovoltaic panels located near the equipment needed to be conducted to ensure that the system remained as cost effective as possible.
Have you designed a combined heat and power system for a school campus?
Richard Sparozic: Our team designed a project which included cogeneration in Guilford, Conn. The system was selected due to the anticipated heating loads throughout the year. Further, it would be capable of generating waste heat when used to generate electricity. Implementing this system required incorporating energy metering metrics that would allow the client to consider equipment operation costs versus utility costs.
What value-add items are you adding these kinds of facilities to make the buildings perform at a higher and more efficient level?
Keith Hammelman: We are seeing a desire to continue the integration of multiple building systems together into a single platform to allow for increased energy efficiency of these systems. This includes the integration of the lighting and building management systems to determine occupancy of spaces and allow the spaces to adjust based on this real time measure of occupancy.
Doug Everhart: High-performance envelope to mitigate envelope heating and cooling loads while providing daylight via high-performance glazing is a balancing challenge for many projects. These efforts can lead to a better indoor environment for both students and staff. Smart controls are another area where the occupancy patterns are critical to follow. System setbacks or smart precool/preheat sequences control the HVAC systems to provide comfort when occupied and save energy when not.
How have energy recovery products evolved to better assist in designing these projects?
Casimir Zalewski: The cost of energy recovery, their prevalence as options in equipment and the client’s familiarity with the different technologies have made it easier on the consulting engineer. Often, these energy saving devices were value engineered out of projects. Reduced cost and not requiring custom units to include them has made it more viable for their use. Additionally, engineers do not have to sole source manufacturers to be able to use the technology allowing the devices to be specified since many districts are not allowed to sole source equipment.
Doug Everhart: Decoupled ventilation systems with the ability to maximize energy recovery from exhaust and outside air streams reduces the energy needed to condition ventilation air. In many cases this can be difficult as the exhaust and outdoor air intake streams may not be in close proximity to one another. This further emphasizes the need for high-performance systems to help overcome the physical location complexities while maximizing the useful Btus within the building.