On Friday 2/12/2021 the CDC released its guidance for reopening schools. Unfortunately, they missed the fact that COVID-19 is a RESPIRATORY disease and cleaning the indoor AIR is key. See this highlight video (4 minutes) that includes the CDC guidance + air disinfection solutions: https://youtu.be/jH-3Jnrri3A

CDC reopening schools

Here is a key graphic from the video that addresses the need for CLEAN AIR at the CENTER of COVID-19 mitigation solutions for schools:

CDC reopen schools

Article: What the CDC Guidelines Don’t Say About Classroom Ventilation and COVID-19 Spread – Source: EducationWeek Excerpt: “Improving indoor air quality may do more than just help schools tamp down on COVID-19 outbreaks, though. One study last year found improving air quality also boosted reading and math achievement, particularly for disadvantaged students living in areas with outdoor pollution.”

CDC GUIDANCE: Schools and Child Care Programs​

Plan, Prepare, and Respond: https://www.cdc.gov/coronavirus/2019-ncov/community/schools-childcare/index.html

Maintain Healthy Environments: https://www.cdc.gov/coronavirus/2019-ncov/community/community-mitigation.html

  • Intensify cleaning and disinfection of frequently touched surfaces
  • Ensure ventilation systems operate properly and increase circulation of outdoor air
  • Ensure all water systems are safe to use
  • Modify layouts to promote social distance of at least 6 feet between people – especially for persons who do not live together
  • Install physical barriers and guides to support social distancing if appropriate
  • Close communal spaces, or stagger use and clean and disinfect between use
  • Limit sharing of objects, or clean and disinfect between use


One of the CDC recommendations is “ventilation”, but increased ventilation of outside air does not disinfect the indoor air. Added outside air ventilation is also costly for facilities, especially in the summer and winter. Purge Virus disinfects indoor air to REDUCE the SPREAD of pathogens like COVID-19, and saves energy along the way that in many cases more than pays for the cost of disinfection.

UVC for K-12 schools

Our Purge Virus team works with our clients to ALIGN the most appropriate disinfection technology to the heating, ventilation, and air conditioning (HVAC) system within any given facility or areas within the buildings. Both Bipolar Ionization and Ultraviolet Light offer proven ways to inactivate COVID-19. See the Disinfection Testing reports.

Bipolar Ionization Disinfection

K-12 SOLUTION for all size Air Handling Units (AHUs)

To learn more see the webinar (36 page file and recording) here: https://purgevirus.com/disinfection-webinar/. Plus, see the Case Studies here: https://purgevirus.com/bipolar-ionization-case-study-highlights/

Ultraviolet Light Disinfection

SAMPLE K-12 SOLUTION for Large Air Handling Units (AHUs)

Market Traction to Date: Since the second half of the 20th century, one of our US production partners has manufactured more than 50,000 germicidal UV light devices. The client list is extensive, and here are just a few examples of major accounts:

Education: Princeton University, Cornell University, Johns Hopkins University, Ohio State University, and the Infectious Disease Research Institute

K-12 Schools increasingly seek clean disinfected air, and one of the most cost-effective solutions is integrating an array of linear Ultraviolet-C (UVC) lamps to both clean the Coil and clean the Air on the Duct supply side. Many grade school and high school facilities have central air conditioning and air handling systems that are appropriate for this type of technology at varying degrees of size.

The sample solution below is for a large size Air Handling Unit (AHU) with the Coil, Plenum, primary Duct, and air flow illustrated in the figures.

Status Quo System: (Pathogens pass through the Coil into the Plenum and Ducts.)

Elevation of Coil (left) Cross Section of Plenum (right) feeding into Ducts

large plenum for HVAC

Upgraded System with (24) high power UVC lamps installed downstream from the Coil (This cleans the COIL for energy savings and cleans the AIR by maximizing pathogen irradiation in the DUCTS.)

uvc  in plenum

This example above is for a property with multiple air handling units. This particular AHU-1 has three rows of two coils that are each 8’ wide x 3.5’ tall. The six coils are stacked three high in the plenum that is 16’ wide x 11.5’ tall. The CFM is 73,600 and the approximate square footage of the conditioned area for this ACH-1 is 60,000 SF.

Coil + Air Disinfection UVC System:

The PV-AUV-CK Series is a modular system (like an Erector Set – known perhaps to many of you who grew up before online games). The modular system is assembled on-site and includes the following:

(3) PV-AUV-CK-8 – $4,200 (Electrical Enclosures with 8 ballasts @ $1,400 each)

(24) PV-AUV-GSL-48 lamps – $3,480 ($145 each)

(24) 30 ft lamp cables – $1,800 ($75 each with SureSeal connections)

(48) lamp clamps – $480 (2 per lamp @ $10 each)

(2) switches – $170 ($85 each)

(2) warning signs $20 ($10 each)

Equipment Cost: $10,150

Highlights: For this air handler each of the (24) UVC lamps are 48” linear “tube” modules. Given the 73,600 CFM and the plenum size of (16′ x 11.5′ = 184 SF), the air velocity is 400 feet per minute in the plenum (73,600 CFM / 184 SF).

24 lamps effectively clean the coil and provide the adequate dose of ultraviolet irradiation to also clean the air. Dose is based on time, intensity, and distance. Each of the (24) 48″ high powered UVC lamps is 119 watts, for a total of 2,856 watts. The resulting dosage is 88,250 μW·s/cm2 (micro-Watt seconds per square centimeter), which is also expressed as microjoules per square centimeter or 88.25 joules per square centimeter. The key with this system is to set the lamps on the downstream supply side far enough away from the coils so that they can clean the air on both sides of the lamps. The ideal distance from the coil is 18″ (in this case with the plenum length of 6′ along the path of air flow). The longer the pass through “purge zone” the better, since the air is moving fast, and time is a factor of dosage.

Equipment + Installation Costs: The cost of the equipment $10,150 / 60,000 SF of conditioned space = $0.17 per SF. Installation labor for a system this size could involve two technicians for two days, including commissioning, measurement and verification. Adding an allowance of about $4,000 for installation brings the installed cost to about $14,000 / 60,000 SF = $0.23 / SF.

Annual Electricity Costs: For a 24/7 facility, 2,856 watts / 1,000 x 8,760 annual hours = 25,018kWh. At the US average of $0.11/kWh, the annual operating cost = $2,752. With 60,000 square feet of conditioned space, this translates to 4.5 cents per SF per year to have disinfected air.

Lamp Replacement Costs: The UVC lamps last for 17,000 hours, which is just over 2 years at 24/7. The cost to replace the (24) lamps is $3,480, which is $1,740 / yr. With 60,000 square feet of conditioned space, this translates to an added 3 cents per SF. The combination of electricity and lamp replacements adds up to 7.5 cents per SF per year to have disinfected air.

Operating less than 24/7: For facilities that do not operate around the clock, turning the system off for 12 hours per day cuts the electricity cost in half and extends the life of the lamps. Given the strike voltage factor on the UVC lamps, each time they are turned off or on, they lose an average of 4 hours of life. Turning off/on twice a day is 730 switches per year and a loss of 2,920 hours per year. So, it is definitely not recommended to synchronize the UVC with the fan motor, but a facility only running a single shift for about 3,200 hours per year, will save money on the energy and extend the life of the UVC lamps by turning them off at the end of each shift. 3,200h of use + the switching penalty of 2,920h = 6,120h per year, which translate to 2.7 years of use over the 17,000 hours of the lamp life. With this single shift model, the energy cost per year drops from $2,752 down to (2,856 watts / 1,000 x 3,200 annual hours) 9,139kWh x $0.11 = $1,005, for savings of $1,746 relative to 24/7 operation.

Energy Savings from Coil Cleaning: The energy savings is typically a function of the age and condition of the Coils. Older systems (e.g. 6 to 10 years old) may generate return on investment (ROI) in under 2 years, and newer and cleaner systems may generate less annual savings extending the ROI up to 5 years or longer. The ultraviolet ROI also takes into account the reduction in maintenance time and materials needed to clean the coils. At a US average of $1.34 / SF for commercial electricity and 10% for cooling, $0.134 is a placeholder for cooling costs per SF. Clean coils can save between 5% – 15%. An average of 10% savings on $0.134 = $0.013 (one and a third cents) / SF per year. For a 24/7 facility this number could go up by more than a factor of two, yielding 2.6 cents / SF / yr. The energy savings almost covers the annualized cost of UVC lamp replacements.

Utility Rebates, Incentives, and $0 Upfront Cost Programs: Many utility companies offer Commercial and Industrial (C&I) incentives for energy savings based on annual kWh saved. Given that COVID-19 has cost the US taxpayers multiple trillions of dollars, we expect to see incentives to disinfect air from federal or state agencies to help reduce the risk of another pandemic. Purge Virus works with each account to identify the most relevant incentives and also provide $0 upfront cost programs through strategic financing partners. Our partners have approved the UVC technology for monthly payment plans, subject to credit review on 3, 4, and 5 year terms.

KEY SPECIFICATIONS and PRICING – See the Technologies page.

germicidal UV light

We welcome the opportunity to provide a technology recommendation and budget proposal based on the size of your AHU plenum(s), trunk duct(s) and CFM. The “GET STARTED” link to the data sheet is a fast and easy way to let us help show you different disinfection options.