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Good Terms to Know from ASHRAE'S COVID-19 Guide

Updated: Feb 18, 2022

As coronavirus started its spread, it took a lot of people in the world time to understand the accompanying terminology.

However, our team of expert engineers is paying close attention to the surrounding resources in order to help our clients and community access information, at least within our expertise.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) responded to the pandemic with a task force, one devoted to providing information to help members of our industry with information to help make more informed decisions.

In this article, we're sharing some of the terminologies that can help create a more informed conversation about protecting the spaces in your building. Sure, many of us have spent hours pouring over the news both in print and on television with many of us learning terms that we never would've predicted to become part of our lives so quickly.

We know that everyone is going through a time of great uncertainty right now, so we're trying to help you by clearing up a few terms that simply aren't in everyone's everyday vocabularies.


Building Air Infiltration: When an uncontrolled inward leakage of air cracks and enters in any building element, typically around the doors or windows of a building. This is typically caused by the pressure effects of wind or by the effect of differences in indoor and outdoor air density.

CADR: Clean air delivery rate, which is the combined effect of how much air is actually moved through a filter in addition to the amount of air moved through the filter in an efficient manner.

Contaminant, airborne: An impurity of any material of an extraneous nature, acting as an unwanted airborne component that may reduce the quality or acceptability of the air.

Droplet Transmission: Droplets that carry infectious pathogens that have the ability to transmit infection when they travel from the respiratory tract of an individual, which necessitates the need for facial protection.

Energy Recovery Ventilation (ERV): The process of exchanging energy normally contained in a building’s exhaust system/air space and using it to treat the incoming outdoor ventilation in HVAC systems. This acts as a way to save energy and potentially money based on ASHRAE’s recommendation to continuously run air conditioning systems to help move potentially harmful particles out of the air at a faster rate.

GUV Lighting: Equipment added to a ventilation system, using ultraviolet germicidal irradiation, to remove harmful particles from cycled air before it enters a room/space.

HEPA Filter: High-efficiency particle air filter that removes 99.97% of particulate matter larger than 0.30 microns in size. There are six types of HEPA filters, which are labeled alphabetically from A to F, each with their own distinct characteristics.

MERV Ratings: Minimum Efficiency Reporting Value, which is the amount/fraction of particles that are removed from the air that passes through a given filter. This is how “filter efficiency” can be measured by engineers and individuals looking to change their filters to a higher grade.

Opportunistic Organism: An ordinarily non-infectious agent that becomes infectious when encountered by a person with a compromised immune system. This occurs from a number of novel organisms, especially in aerosolized respiratory viruses that lack a vaccine or immunity within a population.

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