HVAC Ventilation and COVID-19

To address the questions, concerns and curiosity of our parishioners and other attendees at our Masses and other liturgies, we are sharing important information about the capabilities of our HVAC (heating, ventilation, and air conditioning) system. Many of us have learned from the CDC and other sources that proper ventilation is an important component of an overall set of guidelines for keeping indoor spaces as safe as possible. The US Environmental Protection Agency (EPA) website states:

“An important approach to lowering the concentrations of indoor air pollutants or contaminants including any viruses that may be in the air is to increase ventilation – the amount of outdoor air coming indoors. Ensuring proper ventilation with outside air can help reduce the concentration of airborne contaminants, including viruses, indoors…

In general, the greater the number of people in an indoor environment, the greater the need for ventilation with outdoor air. In other words, the ventilation rate should be based on the number of people that occupy an indoor space (and a few other factors). In fact, CDC has stated that “Indoor spaces are more risky than outdoor spaces where it might be harder to keep people apart and there’s less ventilation.” Give special consideration to increased ventilation when occupancy is high.”

As you may imagine, a building of our size requires a powerful and high capacity HVAC system. In all, we have five (5) massive units that service the church: two (2) for the Gathering Space and the adjacent corridors and three (3) for the nave (the main seating area)*. Year round, our HVAC system is programmed to operate automatically during our daily and weekend Mass schedule and is activated manually for other liturgies such as weddings and funerals.

Regarding the specific air circulation and ventilation rate of our worship space, the three units that service the nave replace the entire volume of air at a rate of five (5) times per hour, with just over 50% of that being outside air. Even at full occupancy of 1050 people, this rate of air replacement and outside air ventilation far exceeds the requirements of the International Mechanical Code, which is the accepted standard for the safety of HVAC systems in the United States and several other countries. With our significantly reduced occupancy of about 225 people per Mass under COVID guidelines, the air circulation and ventilation rate far exceeds minimum requirements.

Also stated on the EPA website: “However, by itself, increasing ventilation is not enough to protect people from COVID-19. When used along with other best practices recommended by CDC and others, increasing ventilation can be part of a plan to protect people indoors.” With the added implementation of other practices for seating, face coverings, sanitizing and social distancing, we have put in place a comprehensive plan to keep safe those who occupy our space.

* A separate HVAC unit services the Chapel.