This page outlines multiple solutions that are applicable for offices to disinfect the air continuously during hours of operation.
The photographs of Ultraviolet (UVC) devices are included below the breakdown of the costs for each of the solutions. This 5,000 sq ft office is and example of a layout that can be used to scale to any size office based on the costs per sq ft included in the tables.
Upon request, we will review your floor plan and provide a similar breakdown of options as below. For a thorough review, we just need to know some of the dimensions and information on your air handling system, specifically the size of the Coil and plenum. The Action Item for the data follows the notes to the analysis tables.
*Note 1: Focus on Coils. In some cases, the Coil system is sufficient without the added HVAC Duct Devices. The added advantage of the Coil system (with or without the duct devices) is the annual energy savings that comes by keeping the Coils clean. 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 ROI in under 2 years and newer and cleaner systems my generate less annual savings extending the ROI up to 5 years. The larger the plenum the lower the cost per sq ft, which also increases the ROI.
Note 2: Hidden from view. The Coil and Duct solution is the most cost effective, and it is “invisible” to the occupants. It is often overlooked as an option, because of the perception that it is more complicated to install than plugging in floor devices or hanging wall mounted devices. The installation cost is definitely higher per device than other options, but there are far fewer devices to install at the Coil and in the trunk duct than in each room.
Note 3: Technology matching. The plugin floor or wall mounted devices are typically more widely used in areas with “acute” disinfection needs, such as dental operatories more so than in general use office environments.
Note 4: Transition to clean. The reception area is one “acute” transition area in an office, that may warrant a floor or wall mounted UVC device to accelerate the disinfection from the hallway to the interior of the office.
Note 5: Calculation factors. The estimates in the tables above are based on some rules of thumb calculations: Each ton of cooling typically correlates to 400 cubic feet per minute (CFM) of air flow. The average static pressure in the HVAC system is .08. The plenum size at the Coil is based on 1.25 sq ft per ton of cooling. The optimal ratio of the plenum is 1:2 (height to width)
Note 6: Electricity cost to operate. The power consumption of these solutions is less than 500 watts. Running during office hours, for 3,200 hours per year, the annual electricity consumption is 1,560 kWh. At the US average of $.11/kWh, the operating cost is $171.60 for the 5,000 sq ft office. This averages to $.034 (three and half cents) per sq ft per year. For information on the operational maintenance cost see the FAQs page.
KEY SPECIFICATIONS and PRICING – See the Technologies page.
To help us size the UVC Coil system for you and provide a free estimate, please LET US KNOW the following. Click for Data Sheet in excel
UVC TECHNOLOGY corresponding to the analysis on this page, with Learn More links for each.
Sample UVC Floor Devices (small and large) Learn More
Sample UVC Wall Mount Upper Air Devices (multiple sizes): Learn More
Sample UVC Coil & Pan Devices: Learn More
Sample UVC HVAC Duct Devices: Learn More
Market Traction to Date:
To date many types of businesses and property types have undertaken germicidal disinfection with ultraviolet light. Certain applications are relevant today more than ever for the commercial office market sector. 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:
Institutions: Infectious Disease Research Institute
Healthcare: New York State Department of Health, Albert Einstein Medical Center, Burbank Hospital, Children′s Hospital Medical Center of Boston, Methodist Healthcare of San Antonio
Food/Beverage: Safeway Stores, Anheuser-Busch, Campbell Soup, Coca-Cola, Pepsi Cola, Del Monte, Dr. Pepper/7-Up, General Foods, Gerber Products, Guinness, Heinz, Hershey’s, Kraft, M&M/Mars, Minute Maid, Ralston Purina, Pepperidge Farms
Education: Princeton University, Cornell University, Johns Hopkins University, Ohio State University
Pharma: Merck, Bristol-Myers Squibb, Eli Lilly
US Government: US Army, Air Force and Naval Hospitals, US Veterans Administration Hospitals, US Department of Agriculture, US Food & Drug Administration
RELEVANT TRENDS: Germicidal Ultraviolet Irradiation (UVGI) for HVAC integration:
Effect of ultraviolet germicidal lights installed in office ventilation systems on workers’ health and well-being: Double-blind, multiple crossover trial.
“The use of UVGI lights was associated with significant (99%) reduction of microbial and endotoxin concentrations on irradiated cooling coils and drip pans in the HVAC system.”
Source: The Center for Health Design
Workers Won’t Return To The Same Office Space They Left.
“Ultraviolet germicidal lights as part of HVAC systems, which isn’t a new technology, might also catch on in a bigger way.”
LARGE SCALE OFFICES
SAMPLE LARGE SCALE HVAC SOLUTION
Large office building owners and managers increasingly seek clean disinfected air to satisfy the requests of their tenants or employees. 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. 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
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.)
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 = $.023 / 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 of 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 my 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.