HVAC For K-12 Schools in North and South Carolina

School children spend a significant amount of time inside at school. The school environment is really children’s, and teacher’s, second home. Creating a safe and productive learning environment is essential to their success. Students have better performance in an optimized learning environment. Healthy indoor air is a critical part of that peak learning environment. Healthy air improves performance by keeping student healthy and alert and reduces absenteeism. The safe environment helps the teachers too.

Why is Indoor Air Quality Critical for Schools?

The COVID pandemic has brought indoor air quality to the forefront. Multiple organization have published varying guidance on how to control indoor air quality, reduce virus transmission, and keep schools open. To protect students in the school environment from the spread of COVID, ASHRAE and the U.S. Department of Education have recommended optimizing fresh air ventilation through the HVAC systems and settings, as well as enhancing filtration through the use of portable air cleaners, properly sized MERV-13 air filters, and UVGI systems.

Classroom Air Quality, CAQ, consists of the follow segments:

  • Air Filtration
  • Air Neutralization
  • Humidity Control
  • Ventilation
  • Thermal Conditioning

HMI represents HVAC manufacturers with product equipment lines that meet the critical design criteria of schools in every segment of IAQ.

Air Filtration in Schools


There has been guidance to increase the performance rating of filters in School HVAC system. Simply installing a higher-performance air filter can create many challenges with existing systems. Some of these challenges include reduction to total airflow, increased material costs, filter availability, and increased maintenance requirements. HMI can help ask those questions and provide optimal solutions for each individual application.

Portable or local fan filtration unitsair filtration system for schools

Standalone units can be installed in every classroom or critical space. These units typically contain a dedicated fan and higher performance filters. They are mobile, so can easily be located where additional air filtration is required.

Filter Units could also be retrofit above drop ceiling so they are invisible to the occupants. The only visible sign of the units are the standard ceiling supply and returns. Mounting the units this way saves space in the classroom. To provide increased protection against the spread of virus, ultraviolet light system can be mounted inside the unit to utilized to neutralize any contaminants that are contained in the filter.


Another effective air neutralization technology is excitation. Excitation technology controls and minimizes particulate levels while producing no negative side effects and can be classified as a Subtractive technology.

An excitation system provides clean air by increasing the size of the particulates in a given space, allowing them to be transported by the HVAC system to the existing filters. Excitation is considered a subtractive technology, as it does not introduce new contaminants into the space to potentially remove existing ones. Excitation systems improve the performance of the existing filters by returning more particulate back to the filter and do not require the ‘plating out’ of particulate on to items in the occupied space.

Air Neutralization air neutralization in schools

Ultraviolet light, or ultraviolet germicidal irradiation ( UVGI ), technology has been around for a long time. The benefits of air disinfection through ultraviolet light exposure are well proven technology. UVGI in the upper area of occupied space has been proven to eliminate viruses in Hospital and School applications.

Installation of UV systems at evaporator cores has been long proven to keep coils clean and operating at maximum efficiency. These systems are easily installed in existing and new air handler units and give thousands of hours of maintenance free performance.


Air Quality Monitoring

A critical step in maintaining healthy air quality is monitoring the quality of the air. The only true way to determine what the quality of the air is in a space is to measure it. HMI offers a number of solutions to dynamically measure critical air quality parameters, CO2, VOCs, etc., in the space.


ASHRAE guidance for humidity is to maintain the relative humidity in the conditioned space to between 30 and 60%. During the coldest times of the year that can be a challenge in the classroom environment. We can provide humidification solutions for complex systems and individual point-of-use applications.

To learn more about humidification click here

School Ventilation

ASHRAE, the Center for Disease Control and Prevention and the Environmental Protection Agency all agree proper ventilation is a key factor for maintaining healthy indoor environments and reducing the spread of disease. Organizations have recommended increasing the amount of outdoor air brought into schools. However, simply increasing the amount of outside air into the conditioned space can create more issues. Depending on multiple environmental factors, outside air may not be clean or fresh. Additional outside air requires additional demand on all the factors of indoor air quality.

Dedicated Outdoor Air Systems, DOAS

Outdoor air requires additional equipment to meet conditioning requirements to improve indoor air quality. A dedicated outdoor air system ( DOAS ) is a unit supplying cooled, dehumidified outside air during summer and heated outside air in winter. The system can include an energy recovery system to take advantage of the thermal condition of the exhaust air in adding preconditioned of the incoming outside air.

Exhaust Fans

Removing stale, contaminated air from occupied space is a critical component to healthy indoor air quality. Exhaust fans have been recommended to run continuously when schools are occupied and for some period of time before and after.

We offer a full line of bathroom and general exhaust fans for all school applications.


Large diameter ceiling fans can provide airflow for effective air circulation and mixing in large common areas, gyms, and any area with a high ceiling. The improved air movement can benefit student comfort and air quality.

To learn more about HVLS fans click here

Air Distribution

Air distribution plays a significant role in how the conditioned air is mixed into occupied space. We have numerous solutions to improve ventilation efficiencies while maintaining occupant comfort.

To learn more about Air Distribution in Schools click here

Thermal Conditioning in Schools

VRF Systems

Properly designed VRF systems can provide healthy indoor air in Schools. The multiple indoor unit configurations give great flexibility in location and operation. Units can be mounted in ductwork to provide a traditional HVAC system look to the classroom. HMI offers Indoor units capable of meeting ventilation air requirements by introducing ventilation air directly at the unit, or operating alongside a separate, dedicated outdoor air ventilation solution.

To learn more about VRF system click here

Rooftop Equipment

Our packaged rooftop units represent some of the most innovative technology in the market. These units deliver exceptional CAQ while operating at a high level of energy efficiency.

Indoor Environment Quality in Schools

Indoor environment quality is impacted by indoor air quality and other environmental conditions. Excess noise can create a challenging environment for learning. If students can’t hear, or are annoyed by some part of the HVAC System, they can’t learn. We offer many products to eliminate noise and vibration transmission from the HVAC equipment. Some of the noise solutions are from the source and some are from the system.

Equipment mounted in the ceiling or above the classroom must be mounted in a manner that does not transmit noise into the space. This equipment ranges from ducts to pipes to air handlers. Decoupling the equipment and distribution system from the building will eliminate a path that noise could transmit through the building structure and into occupied space.

The properly selected and designed isolation products allow the building owners to install complex HVAC systems without the worry of noise and vibration problems. HMI can provide both the technical assistance in the selection and specification of a tailor-made isolation system and the vibration isolation products to meet the required specifications and applications.

Learn more about Seismic and Vibration Isolation

Airborne noise through the HVAC system ductwork can create another noise problem. If the air distribution system isn’t properly designed, or has high air pressure, airflow noise will be an issue.

HMI offers the design and engineering assistance to integrate our line of duct silencers and sound attenuators into a system solution. As a result, you may choose from a selection of “made-to-order” engineered duct silencers that will satisfy the requirements of each application.

Silencers limit airborne noise in ducts and openings in buildings, enclosures, or equipment rooms. Openings into or out of noisy environments are prime candidates for noise control measures. Integration of noise control measures, such as silencers, into the system design requires careful consideration of space constraints, fan selection, and aerodynamic pressure losses. HMI offers silencers that are custom engineered to satisfy the requirements of each application.

All our silencers are backed by independent testing in a NVLAP accredited laboratory in accordance with ASTM E477-06a and AMCA 1011-03.

How exhaust air exits and ventilation air enters the building presents additional challenges in noise generation. HMI fixed blade acoustic louvers are economical, effective, and attractive solution for maximum sound reduction when space is limited. Used as part of the intake and exhaust air systems of buildings, structures, or equipment, acoustic louvers reduce noise produced by the system’s equipment. Acoustic louvers have a relatively large surface area which compensates for their lack of depth. Models are available in varying depths, material types, percent open area, and blade configurations yielding various pressure loss and noise reduction performance.

HMI offers a complete line of pressurized plenums for heating, ventilating, and air-conditioning systems such as outside air intakes, built-up air handling systems, and ductwork. These systems are constructed with modular panels. These panels are designed to be easily installed in the field and are available in various width, length, and metal gage combinations to withstand various positive and negative internal static pressures. A much more cost-effective installation when compared to field fabricated plenums. They are available in the most common thicknesses of 2-inch and 4-inch offering varied levels of transmission loss and sound absorption with thermal break options.


  • Built-up Air Handling Units
  • Panel Duct Systems
  • Outside and Exhaust Air Plenums
  • Supply and Return Air Handling Systems

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