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HVAC Best Practices

As previously mentioned, HVAC systems and the built environment can play an important role in preventing the spread of viruses. To ensure the proper indoor air purity, a good HVAC system should include some or all of the following:

1. (Demand Controlled) Ventilation: When outside air is not provided via separate devices, the HVAC system should provide outside air based on the size/use of the space. Where possible, the HVAC system should include a sensor for carbon dioxide or other pollutants to calculate and correct in real-time the amount of ventilation needed. It is important to be aware that the increase of the ventilation rate may cause an increase of load, and the HVAC unit, if not properly sized, may not be able to provide sufficient cooling capacity. In such situations, it may be appropriate to consider Direct Outdoor Air Supply (DOAS) units, which are specifically designed for large amounts of outside air.

2. Filtration: Filters are rated on their ability to capture and retain particles of different sizes. The industry standard is a Minimum Efficiency Reporting Value (MERV) rating. Filters with MERV >13 have a significant ability to capture particulate matter (PM) and smaller particles. HEPA filters are even more efficient and are able to capture bacteria and viruses. Note that there are important tradeoffs to consider: the higher the filtration requirements, the greater the air pressure drop and the size of the filter. For this reason, the air management system of the HVAC needs to be carefully sized based on the filtration requirements.

3. Other Indoor Air Quality Devices: Numerous technologies are available to reduce the presence of contaminants. Ultraviolet lights, ultraviolet photocatalytic oxidation, ionization, plasma, electrostatic active, active carbon, and other components can be installed to specifically target volatile organic compounds (VOC), bacteria, and viruses. Some of these options can be available as integral parts of the HVAC system