ERV is short for “Energy Recovery Ventilation System” and we have one in our sanctuary because it is an effective way to reduce the spread of airborne viruses in gatherings of people. Last fall we conducted a carbon dioxide survey and discovered that even with only 50 people in the sanctuary, carbon dioxide levels (which are a good indicator of risk — as CO2 levels rise, the risk of infection rises linearly). We even discovered that the levels of CO2 in the sanctuary toward the end of a concert were so high that some people might have experienced drowsiness. An ERV ventilates the building, pulling out stale air, recovering about 70% of the heat and humidity contained in that stale air and pumps in fresh air that has been heated and humidified with the energy from the old air back into the sanctuary.
You may hear the system running. It sounds just like the furnace. With a regular Sunday morning worship service the ERV will run about 50% of the time. With a full house, it would run continually.
Not only should an ERV make the sanctuary a safer place to gather for worship and concerts, it makes it more pleasant. If you would like to see the system or have any questions, just ask!