Engineering in K-12 schools: Energy-efficient, high-performance buildings
Engineers offer practical advice and best practices on how to design sustainable, high-performance K-12 schools.
- Keith R. Hammelman, PE, Vice president, CannonDesign, Aurora, Ill.
- Robert V. Hedman, PE, LEED AP BD+C, Senior associate, Kohler Ronan LLC, Danbury, Conn.
- Pete Jefferson, PE, LEED AP, HBDP, Principal/vice president, M.E. Group, Overland Park, Kan.
- Essi Najafi, Principal, Global Engineering Solutions, Rockville, Md.
- Rodney V. Oathout, PE, CEM, LEED AP, Regional engineering leader/principal, DLR Group, Overland Park, Kan.
- Sunondo Roy, PE, LEED AP BD+C, Vice president, CCJM Engineers, Chicago, Il.
CSE: Energy efficiency and sustainability are often the No. 1 request from building owners during new building design. What is your experience in this area?
Oathout: No doubt that sustainability is important; however, many of my K-12 clients are interested in energy efficiency and how costs avoided in building operations can be used for other purposes. DLR Group recently partnered with the Institute for the Built Environment (IBE) at Colorado State University for a research study of elementary school designs. The schools participating in the study were designed with sustainability in mind, but had not been evaluated for design effectiveness or the long-term impact on operations. The findings were interesting. The complete report, titled “Linking Performance & Experience – An Analysis of Green Schools,” can be downloaded from the IBE website.
Jefferson: Some of the earliest adopters of energy efficiency and sustainability were our K-12 clients. They are clients that “build and hold” properties, so they actually do care about long-term operational costs. So we’re really proud to have worked on some really sustainable schools. Just in the past 3 years, we have completed five LEED Gold K-12 projects, including one that achieved net-zero energy its first year, and the first Collaborative for High Performance Schools “Verified Leader” project in the country. We have another six K-12 projects that are in the submittal process for LEED Gold certification this year, so we’re really excited for those districts.
Najafi: High efficiency and sustainability demand has helped the HVAC industry to move technologically to the systems of the 21st century. After almost 50 years of slow progress and limited innovation, the past 10 years gave way to systems such as magnetic chillers, chilled beams, and variable refrigerant volume/flow systems, which push the envelope of efficiency to levels never attained before. LEED requirements, green building, and Energy Star requirements—and the willingness of building owners to meet them—have helped engineering designs to move from the imaginative creations of a few innovative engineers of the past, to today’s practices of mainstream engineering.
Hammelman: Energy efficiency is a primary driving factor for new buildings, but our clients often ask us to balance the energy cost reductions with long-term operability issues, such as the possible cost increases in maintenance or operational complexity of the systems. CannonDesign incorporates energy modeling in the early project stages to focus on optimum designs for the envelope, lighting, and HVAC systems, while balancing the client’s desires to understand the long-term operating costs. We also establish a series of performance goals for clients that can be measured at the project’s completion to determine the project’s success.
Hedman: The request for energy efficiency and sustainability has been universal for all new school projects that we have designed in the past 5 years. Municipalities are realizing while there is an initial capital cost to build a new school, the operating costs are recurring for the life of the building.
CSE: Many aspects of structure sustainability (power, HVAC, maintenance, etc.) require building personnel to follow certain practices in order to be effective. What, if anything, can you as an engineer do to help increase chances of success in this area?
Roy: The commissioning process basis of design (BoD) has to be written clearly and simply to capture specific design features that may be beyond the typical building engineer’s area of knowledge or expertise. Where we are expecting the system to be operated in a nonstandard way, it is imperative that the BoD identify unique systems and operational requirements. Beyond that, these points need to be addressed specifically during the final commissioning training of the staff and explicitly note the implications of not following the correct maintenance or operation procedures. If the training is being videotaped, make a point of including the special considerations and implications. If you surprise the operating staff with unique design solutions, the outcome is typically not good.
Najafi: There is no doubt that as the technology surrounding the MEP and fire protection systems is becoming increasingly more technologically advanced, the need for experienced and computer-savvy building engineers and technicians is also on the rise. Proper and clear control sequences for the operation of the systems, automated processes/controls, and operator-friendly graphic interface for monitoring and controlling the various building systems are a few of the practices followed by the current designs in an effort to simplify the human interface and remove the technological fear from operators with limited knowledge in the computer field. We have consistently advised our clients to retain the services of experienced commissioning agents and have refined our specifications to provide detailed testing and demonstration of the systems as part of delivering the project to the building owners.
Oathout: This question is the basis for one of the biggest challenges engineers have when designing K-12 facilities. We do our clients a disservice if the system design is overly complex so they have no chance of operating it successfully. It is important to understand your clients’ experience and capabilities in advance of starting the design. How technologically proficient is their building staff? What kind of staff turnover can we anticipate? It’s essential to design systems that school districts can operate efficiently over the lifecycle of the building.
Hedman: Understanding the intent of how the system was designed to operate, along with training on using the building management system, is critical. We have found it important to include training of the maintenance staff as part of the project specifications.
Jefferson: I think that if there’s one area where my design philosophy has evolved, it’s to work harder to pursue simplicity in the design. That’s a lesson learned from working with woefully understaffed and undertrained districts, helping them understand how their building is supposed to work. I’ve really come to believe that sometimes chasing that last little bit of energy efficiency, if done through adding complexity, can actually set the building back and result in poorer performance. That’s a big reason why we’re all-in on load reduction and passive strategies—there’s no complexity.
CSE: Could you please share a success story in which you were able to deliver a highly sustainable project to a school client?
Hedman: As part of the groundbreaking Kohler Environmental Center (KEC) project, Kohler Ronan designed systems compliant with the utmost in green building standards. Earth duct ventilation is just one such system. By preconditioning the outside air, the earth duct system significantly reduces heating and cooling related energy use and corresponding costs. Together with a combination of active and passive systems, earth ducts help reduce total energy consumption within the facility by more than 50% compared to ASHRAE 90.1-2004. The potable water consumption has been decreased by more than 60%. As the 31,325-sq-ft building was designed to achieve net-zero energy usage, 100% of its annual energy demand is met on-site via a 296 kW photovoltaic array, roof-mounted evacuated solar tubes, and waste oil. This LEED Platinum facility has been equipped with interactive monitoring technology, allowing building occupants to track individual energy use as well as the building’s performance.
Najafi: On a recently completed school project, we specified a Lutron Quantum Total Light Management system, which consists of digital dimmable ballast, automatic dimming, and lighting control and daylight harvesting with integral motorized shade controls. The project was a success, providing occupant comfort and energy savings. All the classrooms of the school have exterior exposure with an ample number of windows, making the project ideal for implementing daylight harvesting. As a result, most classroom light fixtures are dimmed to about 50% throughout the day.
Roy: This question brings up a long-standing issue most designers have with sustainable designs. We very rarely receive long-term measurement and verification data for individual projects. With tight design budgets, there’s very little opportunity to follow up with school administrators who would have the data to determine operational efficiency versus design efficiency. Some school districts are better than others in tracking the information at a high level for the full portfolio of schools and maybe even have some information for individual projects. However, this information rarely makes it back to the designers. Additionally, the operational efficiency of a design is ultimately subject to the experience and budgets of the operating staff to maintain and operate the systems as designed. We designed two similar template schools concurrently with very similar systems. On paper, they both achieved LEED for Schools Gold. Unfortunately, we do not have the long-term data on how energy-efficiently each school is operating.
Jefferson: One of my favorite projects to this day remains the LEED Gold Sangre de Cristo PK-12 in Mosca, Colo. It’s in climate zone 6, and design conditions there require us to design for -24 F in the winter and 83 F in the summer. The thing we realized is that it also had tremendous solar resources, so we take advantage of passive solar heating, and roughed-in equipment for photovoltaic (the utility company doesn’t allow net-metering currently). After 3 years, it’s using 50% less energy than National Renewable Energy Lab/Dept. of Energy reference buildings in that climate.
Hammelman: Champaign Unit 4 School District, Booker T. Washington STEM Academy was the first K-5 STEM magnet school in Illinois. The district sought to reduce electricity costs 30% below ASHRAE 90.1-2007 guidelines. To achieve the 30% energy savings, the fully integrated design team developed a total-building design that included reduction of lighting power density, ample daylighting, high-performance envelope, and a dedicated outside air system with integral energy recovery and geothermal heating and cooling. Challenges included locating the geothermal well field on the school’s limited site, coordinating nonstandard ductwork, and achieving the aggressive acoustic requirements for classrooms specified in LEED for Schools. Our team exceeded the goal with a resulting building performance 40% more efficient than ASHRAE 90.1-2007.
CSE: Could you please describe any experience you have using sustainable heating/cooling tech, such as geothermal systems?
Najafi: We have several past projects employing one or two innovative systems such as geothermal, and as an example of the direction the practice is taking, currently on the boards we have two projects which employ energy-effective conditioning and ventilation systems in combination, including ground-coupled (commonly called geothermal) heat pumps using distributed variable refrigerant flow (VRF) terminals and dedicated outside air systems (DOAS), displacement conditioning/ventilation, in-slab radiant heating and cooling, electric/thermal solar renewable energy, and rainwater harvesting. Our firm is continuing to push the limits of sustainability by integrating not just geothermal systems, but also an array of renewable systems and energy-efficient designs.
Hedman: We recently completed a private school project using an earth duct. The earth duct consists of runs of precast concrete duct installed at 4 ft below grade. Fresh air is drawn in and routed through the concrete ducts to an air handling unit. The constant earth temperature preheats or precools the air depending on the season. A temperature difference of approximately 15 F has been achieved using the earth duct. This results in a reduction to the total cooling and heating building load.
Oathout: Battle High School in Columbia, Mo., is one of our newest facilities served by a ground-source heat pump system. There are 267 geothermal wells, each 400 ft below the surface, that form the heat exchanger between the closed loop and the earth. Other sustainable features associated with this facility are energy recovery of the ventilation system and lighting controls system integrated in the building management equipment. The building management system also has a specialized control sequence to limit electricity demand.
Jefferson: Geoexchange systems are pretty common in our K-12 projects. We really believe in de-coupling ventilation air from heating/cooling systems, so almost all of our schools are designed with dedicated outside air systems. In our climate, indirect/direct evaporative cooling makes a lot of sense, especially paired with displacement ventilation, so we’ve done a number of those systems as well.
CSE: Please describe your experience with high-performance building projects in the K-12 arena.
Hedman: The most recent projects we have designed to achieve high performance included ice storage, ground source heat pumps, and cogeneration. Ice storage allowed for a reduced plant size and electric consumption. Ground source heat pumps allowed us to design a system with energy efficiency ratios (EER) and coefficient of performance (COP) not typically achieved with standard refrigeration and heating equipment. Cogeneration provided the opportunity to generate a portion of the electrical building load while producing high-temperature hot water as a byproduct. The high-temperature hot water was used to supplement the building hot water heating plant.
Najafi: We believe that we provide innovative engineering to our sustainable focused projects by using the value of true integrative design. We work with owners to ensure that barriers—such as misplaced expectations or outdated project development practices of the past—are removed by engaging the owners and other stakeholders in the development of the owner’s project requirements (OPR) with feedback on the ramifications of decisions regarding energy performance. We work closely with the architects to ensure that the building is being designed appropriately to support high-performing engineering systems. We work closely with other team players to ensure that we have considered and integrated all sustainable and creative design solutions. We take into consideration the availability of maintenance personnel and their expertise to help ensure that the building will perform well throughout their life. The engineering systems play a large role in overall building performance, but it’s a true integrative design approach that involves input from the complete design team, the owner, the end user, and the current and future maintenance personnel that help to create a truly sustainable and high-performing building. Taking these items into account has allowed us to work on K-12 schools that are achieving LEED Platinum as well as obtaining the sustainable standards for local jurisdictions, such as the Henderson Hopkins School, which is the first school to go through Baltimore’s Green Building Standards certification program.
Roy: Designing a high-performance building is a state of mind first and then a process to follow up. When the architectural team, the engineering team, and the construction team work in concert to contribute to their fullest capability in their areas of responsibility to provide high efficiency systems and then integrate the design into a holistic design and construction process, that is how one can design a high-performance building. We make a point of working with architects who understand this philosophy and work collaboratively to establish realistic design goals and agreed-upon strategies to achieve those goals. Where we have worked in a design-build framework with the construction team in the process from the beginning, the outcomes are typically better. When the delivery process is the traditional design-bid-build framework, the outcome is less predictable—particularly in public projects where typically the low bidder is selected and there is no guarantee the three teams will see eye-to-eye. Of our two concurrent school designs I spoke of, we had extensive coordination with the two different architects on the two projects. We had buy-in from the architects that the design would be a holistic approach to achieve the best outcomes possible. One project had a slightly better contractor than the other in terms of buying in to the integrated design and construction concept. The construction process was definitely smoother with the more cooperative contractor, resulting in fewer construction and commissioning issues.