In this roundtable, engineers share strategies for addressing indoor air quality in schools through advanced ventilation, humidity control and energy-efficient heating and cooling solutions.
HVAC and plumbing insights
- Dedicated outdoor air systems help schools improve ventilation, control humidity and support healthier classrooms.
- High-efficiency heating and cooling systems can reduce energy use while maintaining strong indoor air quality.
Respondents:
- Grady Henrichs, PE, K-12 Education Engineering Leader, DLR Group, Omaha, Nebraska
- Abdullah Khaliqi, PE, MCPPO, CPQ, Principal, Academic, Fitzemeyer & Tocci Associates Inc., Woburn, Massachusetts
- Amber Lang, LEED AP BD+C, Associate Vice President, CannonDesign, Chicago
- John Mongelli, PE, Senior Associate, Kohler Ronan Engineers, Danbury, Connecticut
- Steven Mrak, PE, Vice President, Peter Basso Associates Inc., Troy, Michigan
Describe a recent project in which you addressed indoor air quality (IAQ) issues to account for health concerns.
Grady Henrichs: Research has shown repeatedly that IAQ is a critical component of student learning outcomes, ensuring that students stay alert, healthy and able to learn. A recent project design included the use of air scrubbing products that are shown to clean recirculated air of harmful contaminants that cannot otherwise be mitigated through traditional filtration methods to ensure exceptional air quality for learning environments.
Abdullah Khaliqi: In a recent K-12 school renovation, we addressed IAQ concerns by upgradingto a dedicated outdoor air system (DOAS) with MERV 11 filtration and carbon dioxide sensors. The project aimed to improve IAQ and reduce airborne transmission of viruses and allergens in previously underventilated classrooms. One challenge was retrofitting equipment in tight ceiling spaces. We solved this by using low-profile duct systems and placing ceiling-mounted energy recovery units in strategic areas.
John Mongelli: We worked on a school where mold was an issue. A poor building envelope coupled with incorrectly controlled unit ventilator heating, ventilation and air conditioning (HVAC) systems led to frequent high-humidity conditions and subsequent mold growth within the building. Our firm designed new 100% outside-air dehumidification systems that used desiccant technologies to deliver very dry ventilation air throughout the building. Mold remediation was performed and the new system has prevented its recurrence.
What unique heating or cooling systems have you specified into such projects?
Grady Henrichs: DOAS continues to be proven to be one of the best methods of maintaining excellent IAQ in most climate environments, especially extreme cold or humid climates. DOAS systems incorporate energy recovery devices to precondition outside air but also include additional means to heat or cool depending on the system, allowing them to be applicable in extreme climates. These systems are now designed to provide ventilation air at a low enough dew point to offset latent heat gain in the space, which ensures exceptional IAQ and allows secondary systems to operate efficiently.
Abdullah Khaliqi: In K-12 projects, weโve specified unique HVAC systems such as ground-source heat pumps, variable refrigerant flow (VRF) systems and DOAS with energy recovery to meet energy goals and improve IAQ. In one project located in a hot, humid setting, we designed a decoupled system using DOAS for ventilation and scheduled run times ahead of the school morning. The challenge was controlling humidity without overcooling. We addressed this by incorporating electric reheat coils and dew point-based controls. This approach improved occupant comfort and energy efficiency and helped meet strict IAQ standards for student health and safety.
What types of unique building pressurization have you designed in K-12 schools? Describe the project.
John Mongelli: Spaces such as nursesโ suites are designed with a dedicated exhaust fan, allowing the suite to remain negative relative to the surrounding areas. Additionally, science rooms with fume hoods and art rooms are designed to maintain negative pressure for fume and odor control.
Steven Mrak: Building pressurization control can vary from simple gravity relief hoods to more complex variable speed relief systems that can provide makeup air accommodations for kitchens, general restroom exhaust or process exhaust. As these needs come and go in a school throughout the day, it becomes hard to define a โsteady stateโ condition regarding building pressurization. To help accommodate these different scenarios, differential building pressure control can be used to vary the speed of relief fans. This uses atmospheric pressure and compares it to the pressure inside the building, controlling the speed of the relief fans to provide a consistent, usually slightly positive, differential pressure.
What unusual or infrequently specified products or systems did you use to meet challenging heating or cooling needs?
Grady Henrichs: Geothermal systems are now a proven technology shown to handle challenging climates extremely well. They are especially useful in the Midwest or any climates seeing cold winters and hot and humid summers. These systems allow one to use the ground to store heat extracted from the building in the summer to then heat the building in the winter. When paired with a DOAS, geothermal can be applied to several energy-efficient systems to best meet the buildingโs needs
Abdullah Khaliqi: In K-12 projects with complex thermal or spatial constraints, weโve specified active chilled beams, VRF systems and radiant heating panels to meet comfort and energy goals. In one particularly tight ceiling retrofit, active chilled beams were ideal for providing silent, efficient cooling with limited ductwork. For schools in mixed climates, VRF systems offer zoned control, reduced energy use and better adaptability to changing occupancy. Weโve also used desiccant dehumidification systems in humid regions to control moisture independently from temperature. These less commonly used systems require precise control strategies but offer long-term performance, flexibility and occupant comfort.
John Mongelli: Chilled beams have been specified on several of our projects. It is a system that allows heating and cooling with low fan-energy usage making it desirable for high-performance buildings. It allows for ductwork sized for the ventilation load or primary air load needed to meet the target beam capacities, whichever is greater. The result is reduced ductwork distribution, enabling higher ceilings, smaller shaft footprints and additional space for other trades, as well as pathways for future distribution to support new technologies. One challenge of using chilled beams in schools is maintaining proper dew-point control through the ventilation system. Chilled beam cutoff safeties should be considered to protect against condensation if dew-point control is lost. Examples include monitoring dew point in each space, installing pipe-mounted condensate sensors on chilled water lines and installing window sensors on operable windows.
Steven Mrak: Like most systems, VRF has its place and applications. While maybe not a solution for all situations, one instance where it brings value is with limited ceiling space. The relatively small refrigerant pipes can be routed in tighter spaces than an insulated supply duct carrying the same cooling capacity. The VRF system can also provide occupants with the level of individual control expected. Using heat recovery type VRF systems (also known as a three-pipe system) can increase overall system energy efficiency by recycling waste heat/cooling around the system.
How have you worked with HVAC system or equipment design to increase a buildingโs energy efficiency?
Abdullah Khaliqi: We improve building energy efficiency through right-sizing equipment, using energy modeling to guide design decisions and integrating high-efficiency HVAC technologies. We specify variable speed drives on pumps and fans, demand-controlled ventilation (DCV) and heat recovery systems to minimize energy waste. In classrooms, decoupling ventilation from thermal loads with DOAS and pairing with VRF or radiant systems enhances control and reduces consumption. Controls are optimized through building automation systems (BAS) to adjust operation based on occupancy and schedules. Early collaboration with the architect and energy consultant helps align HVAC choices with envelope performance and district sustainability goals.
Amber Lang: We work closely on HVAC system and equipment design to maximize energy efficiency in K-12 schools. This includes selecting high-efficiency chillers, boilers and air-handling units as well as implementing variable air volume (VAV) systems and energy recovery strategies. Integration with building automation allows real-time monitoring and optimization of temperature, ventilation and airflow based on occupancy and environmental conditions. Daylight harvesting and coordination with lighting controls further reduce energy use. By combining efficient equipment, smart controls and thoughtful system integration, we create learning environments that are comfortable, sustainable and cost-effective over the buildingโs lifecycle.
Steven Mrak: Implementing energy recovery devices in HVAC units has become a more common practice. Beyond energy code requirements, energy recovery devices like enthalpy wheels, energy cores and plate heat exchangers are being used on smaller systems, really trying to capture as much energy as possible, even down to the individual classroom level. While the energy savings at each unit may not be substantial, multiply that by 30 or 40 classrooms and the savings can become real.
What best practices should be followed to ensure an efficient HVAC system is designed for this kind of building?
Grady Henrichs: The best way to ensure maximum efficiency is by performing an energy analysis early in the project as building footprint and envelope decisions are being made, then continuing to model different HVAC solutions to determine the most efficient system for the project. Once the energy analysis and system design are complete, commissioning of the HVAC system is a critical step to ensure it is operating as intended and as efficiently as the modeling has assumed.
Abdullah Khaliqi: Best practices for designing efficient HVAC systems in K-12 schools include starting with comprehensive load calculations and energy modeling to inform system selection. Prioritize zoned HVAC systems to match occupancy schedules and space types. Incorporate heat recovery ventilators, variable speed drives and DCV for optimal performance. Use open protocol BAS to monitor and control equipment in real time. Coordinate closely with architects for optimal solar orientation and envelope design and involve facility staff early to ensure maintainability. System simplicity, flexibility and integration with lighting and IAQ controls all contribute to long-term operational efficiency.
Amber Lang: Best practices for designing efficient HVAC systems in K-12 buildings start with understanding the unique needs of each space, including classrooms, labs, gyms and common areas. Early coordination with architects and other trades ensures proper space allocation, duct routing and ceiling integration. Systems should incorporate energy-efficient equipment, VAV controls, energy recovery and smart building automation to optimize performance. Daylight harvesting and occupancy-based controls further reduce energy use. Additionally, selecting scalable and maintainable systems, planning for future upgrades and performing load analysis and modeling are essential to deliver HVAC solutions that balance comfort, energy efficiency and long-term operational reliability.
John Mongelli: Kohler Ronan has an in-house energy modeling group that our engineers rely on to support early design decisions. This group often collaborates with architects to model various HVAC systems, envelope performance and passive design elements, helping determine which features make sense to implement for a more efficient building while maintaining the project budget. We believe that every high-performance school should incorporate an energy model so that both engineers and architects can verify that their design meets the project goals.
What type of specialty piping, plumbing or other systems have you specified recently?
Amber Lang: As science, technology, engineering and mathematics programs continue to grow in K-12 environments, plumbing systems are becoming more complex to support evolving instructional needs. Science labs are moving beyond traditional classroom experiments toward more research-based activities, which drives the need for specialty plumbing systems. Recent projects have included additional lab gases, higher water quality requirements, specialized waste piping and more robust drainage and safety provisions. These upgrades require close coordination with educators and safety standards to ensure the systems support hands-on learning while remaining appropriate, safe and maintainable for a K-12 setting.
What are some of the challenges or issues when designing for water use in such facilities?
Abdullah Khaliqi: Designing for water use in K-12 schools presents challenges like peak demand variation, fixture durability and balancing efficiency with performance. Facilities like locker rooms, kitchens and science labs have distinct water quality and pressure requirements. Meeting local conservation goals often requires low-flow fixtures, but careful selection is needed to ensure usability for young students. We also address hot water delivery time to avoid waste and complaints, often using recirculation systems with timers or sensors. Maintenance access, cross-connection protection and future capacity are also critical design considerations in high-use school environments.
Amber Lang: Designing for water use in K-12 facilities presents unique challenges, as enhanced water conservation measures have historically been more common in commercial and higher education projects. While K-12 schools were not always primary targets for aggressive conservation strategies, that is changing. Designers must balance durability, hygiene and maintenance needs with reduced water use. There is also an increasing focus on educating students and staff about water conservation, recognizing that schools play a role in shaping future conservation habits. This shift requires thoughtful fixture selection, system design and coordination with district operations teams.
