Air purifiers are proven tools to reduce COVID-19 spread in indoor spaces such as churches. But choosing which air purifier is best for a church and how many are needed can seem complicated. In this article, we take you step-by-step on how to choose the best COVID-19 fighting air purifier for churches, mosques, synagogues, or any other large place of worship.
Step 1: Measure Size (Volume) of Church
Before choosing an air purifier for a church, we need to know how much air the purifier needs to clean.
First, measure the area of the church floor in square feet or square meters (L * W). Next, multiply this number by the height of the church to get the total volume. If the number calculated is in cubic feet, divide this number by 35 to get the volume of the church in cubic meters.
Step 2: Calculate the CADR Needed to Clean the Church
Next, we need to calculate how much “power” is needed from an air purifier to clean the volume of air calculated in step 1. The amount of air an air purifier is able to clean is given by its CADR rating. The higher a CADR rating, the more air the air purifier can clean per hour.
To do this, we first need to multiply the volume of the church by 2. The number after multiplying the volume of the church (in meters cubed) by 2 is the CADR needed (cubic meters per hour) from a purifier to clean the church.
The reason we multiply by 2 is churches should aim to have all the air in a church cleaned and replaced with new air at least 2 times per hour. This number is the same as ASHRAE recommends for larger areas such as retail shops. Therefore, we need to find an air purifier that is powerful enough to clean this much air.
Step 3: Find HEPA Air Purifier(s) with a CADR at or Above Number Calculated in Step 2
CADR ratings are given in two measurements, either cubic meters per hour (CMH) or cubic feet per minute (CFM). The CADR needed for the church calculated above is in cubic meters per hour (CMH).
Note: If only the CFM is given for a specific air purifier, this can be converted to CMH by multiplying by 1.7.
The CADR of powerful air purifiers typically ranges from 500-900 m3/hour. Since churches and places of worship typically are quite large, the CADR needed will likely be many times that of even the most powerful air purifiers. Thus, multiple air purifiers will be needed.
Be aware, these ratings are for the purifier’s highest setting. Many air purifiers’ highest settings can be quite loud and could possibly be a disturbance (see step 6).
Step 4: Choose HEPA Filter Air Purifier, Avoid Purifiers With Add-ons
The best type of air purifier for churches to protect churchgoers against COVID-19 is a HEPA filter air purifier. HEPA filter air purifiers are highly effective at filtering out particles the same size as COVID-19.
When choosing a church air purifier, avoid extra add-ons such as UV lights and ionizers. These add-ons increase cost and may pose an additional health risk for those in the church.
Step 5: Consider Cost/Lifespan of Replacement Filters
The cost and lifespan of a HEPA filter should be considered in addition to the upfront cost of the purifier. Many air purifier companies are not transparent with HEPA filter replacement recommendations and how they calculate the numbers. But roughly calculating the yearly cost of HEPA replacements can help you compare the operating costs of different air purifiers.
Step 6: Consider Noise Level
Many air purifiers can get loud on high settings. It is important to choose an air purifier for the church that does not cause a disturbance to church services or concerts. You can find how loud an air purifier is by checking its noise level measured in dB. Anything over 55 dB will likely cause disturbances in the church.
Important tip: Make sure to find the noise level for each air purifier on its highest settings. Some air purifier companies publish the noise levels of their purifiers on the lowest settings, which can be misleading.
Real-World Example: Choosing a Church Air Purifier
Let’s go through the process of finding air purifiers for a 60 by 150 feet (18.3 by 45.7 meter) church with 20-foot (6 meter) ceilings.
Step 1 is to calculate the volume of the church in meters: 18.3 x 45.7 x 6.0=5018 cubed meters.
Step 2 is to multiply the volume by 2: 5,018 cubed meters x 2=10,036. The CADR of the purifier needed for the church should be at least 10,036 m3/hr.
Step 3 is to find enough air purifiers whose CADR adds up to at least 10,036 m3/hr.
Note, if the CADR rating of an air purifier uses CFM like the air purifiers below, multiply this number by 1.7 to get the CADR in m3/hr.
From the Smart Air product line, the Blast air purifier with CADR of 890m3/hr is the best and most powerful air purifier for large spaces. For a large space such as a church with 10,036 CADR needed, the church would need approximately 11 Blast air Purifiers to best clean the church air inside the church.
Steps 4,5,6: Lastly, make sure the air purifier uses HEPA filters without other gimmicky technology, take note of filter replacement costs, and ensure the purifier has acceptable sound levels.
How Smart Air Protects Churches Around the World
Smart Air is a certified B Corp and social enterprise committed to helping people breathe clean air. Hospitals, schools, and businesses all across the globe use Smart Air’s no-nonsense Blast air purifiers to provide pollution-free air and reduce COVID-19 spread.
Smart Air’s Blast industrial air purifier is one of the most powerful air purifiers on the market. It has can clean areas up to 130 sqm (1400 sqft) in size. Some large churches use Smart Air’s Blast to provide their churchgoers with the cleanest air possible.