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Four IAQ Steps to Prepare Schools For Reopening

July 31, 2020
Reflecting new WHO warnings on aerosol transmission, Trane identifies how schools can improve classroom air quality environments with key steps.


(Davidson, NC - July 29, 2020) | To prepare for school re-openings, whether now or in the future, school administrators have been focused on how to accommodate social distancing, equip teachers and students with Personal Protective Equipment (PPE), reduce class size and sanitize surfaces. However, there is another key consideration required for success: indoor air quality.

After receiving a petition from 239 experts, the World Health Organization (WHO) has revised its guidance on COVID-19 modes of transmission. WHO states that “aerosol transmission, particularly in indoor locations where there are crowded and inadequately ventilated spaces where infected persons spend long periods with others, cannot be ruled out.”

As with other airborne transmissions, like measles, there is potential for the virus to spread through particles known as aerosols, which can hover in the air after a person has left the area.

Few spaces have more people moving around in the same area than schools. This input about how COVID-19 may spread propels air quality onto the list of things schools need to evaluate and improve to restore confidence among teachers, families and students about going back to school.

HVAC Strategies Dilute, Exhaust, Contain and Clean Air in Schools

School heating, ventilation and air conditioning systems (HVAC) play a critical role in improving indoor air quality. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE®) indicates that making changes to the operation of HVAC systems can reduce exposure to airborne contaminantshowever, the transmission and mitigation of COVID-19 in buildings is yet to be tested and confirmed.

To help building managers and school administrators evaluate air quality in their schools and navigate how to improve it, Trane® offers the Trane® Indoor Air Quality Assessment. The assessment identifies areas of improvement and provides concrete guidance to optimize indoor air quality, including:

  • A report with actionable, strategic recommendations to improve indoor air quality
  • Guidance on what systems to update or improve to address critical issues
  • Options to implement recommendations and a documented list of completed results

​​​​​The assessment focuses on four critical areas of indoor air quality: dilute, exhaust, contain and clean.

1. DILUTE - Proper ventilation ensures that plenty of fresh, outdoor air enters the building to dilute the build-up of certain contaminants indoors. In the past, the practice was to limit the intake of outdoor air to reduce operating costs. However, with new, indoor air quality priorities, schools should significantly increase the amount of fresh air they are using in their ventilation for air dilution.

Ron Cosby, Thermal Systems and Technology Leader at Trane Technologies, says best practice is to consistently run an HVAC system to remove stagnant air from the room and replace it with fresh, clean air.

  • Change the setpoints on the HVAC system’s fresh air dampers that regulate the intake of outdoor air into a building. Increasing airflow from the outdoors flushes out stale, indoor air to help remove micro-biologicals, which may include certain viruses and other contaminants.
  • Disable demand-controlled ventilation in school buildings originally set up to reduce outdoor airflow to save energy. 

2. CONTAIN - Containment is the ability to control humidity levels inside a building. Controlling indoor humidity levels keep students and teachers comfortable, but it can also reduce the uptake and impact of certain viruses.

  • Incorporate humidity sensors to maintain humidity levels between 40% and 60% relative humidity (RH).
  • If humidity levels drop below 40% relative humidity, seek the input of an HVAC expert to determine how to raise the humidity without generating condensation within the building. 

3. CLEAN - Cleaning air reduces particles, odors, and micro-organisms and micro-biologicals such as mold, bacteria and certain viruses. Air cleaning is advantageous to maintain an optimal environment for students and staff, but now it’s even more critical.

There are a variety of different air cleaning technologies ranging from Ultraviolet Germicidal Irradiation (UVGI) to photocatalytic oxidation. However, the quickest and most cost-effective way to enhance air cleaning is by upgrading HVAC filters to ones that more aggressively capture certain microbiological particles.

  • Upgrade filters to ones with high MERV ratings. The Minimum Efficiency Reporting Value (MERV) range spans eight to 16. The rating system created by ASHRAE indicates how effectively the filter captures contaminants based on contaminate size. The higher the MERV number, the smaller and finer the particles it can potentially capture. ASHRAE recommends building managers use filters rated MERV13 and above.
  • The most effective filters are High Efficiency Particulate Air (HEPA) filters to reduce both larger micro-biologicals and those that adhere to aerosols and small particulates.
  • Consider a long-term air cleaning solution. For example, the Trane Catalytic Air Cleaning System (TCACS) neutralizes and significantly reduces certain contaminants in the air using an advanced photocatalytic oxidation process. 

4. EXHAUST - Expelling exhaust air from a building is also important. Especially in small, closed-off rooms such as bathrooms and kitchens that use exhaust fans to facilitate airflow. Run exhaust fans 24/7 to increase airflow in these spaces.

The Trane Indoor Air Quality Assessment

This work is a science-based, data-driven analysis of how a building’s indoor air quality adheres to current industry recommendations and guidelines. Trane engineers and technicians will examine and provide relevant data in critical areas that influence indoor air quality. Where possible, Trane can conduct the assessment remotely through the building automation system (BAS). Building operators will receive actionable data and insights about the building’s overall air quality to take immediate action and plan for future improvements. The assessment is part of the Ready for Now, Resilient for Tomorrow program from Trane Technology that includes four service offerings – Indoor Air Quality Assessment, System Startup, Energy Checkup and Remote Services.

To learn more about the Ready for Now, Resilient for Tomorrow services, or connect with an HVAC expert visit

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About Trane

Trane – by Trane Technologies (NYSE: TT), a global climate innovator – creates comfortable, energy-efficient indoor environments for commercial and residential applications. For more information, please visit or

About Trane Technologies

Trane Technologies is a global climate innovator. Through our strategic brands Trane® and Thermo King®, and our portfolio of environmentally responsible products and services, we bring efficient and sustainable climate solutions to buildings, homes and transportation. Visit

Media Contacts:

Cole Zerboni, Portavoce PR for Trane Commercial, [email protected]

Kelly Hydeck, Trane Technologies, [email protected]