While masking, surface cleaning and social distancing can help mitigate potential virus spread, considering other measures can help restauranteurs reduce potential spread of certain airborne virus in a restaurant environment.

Why This Matters: Addressing potentially infectious aerosols can help increase confidence in your restaurant environment while helping you enhance the indoor air quality and ventilation of your space. 

ASHRAE^®, (formerly the American Society of Heating, Refrigerating and Air-Conditioning Engineers), which aligns its recommendations with the Centers for Disease Control (CDC) and the World Health Organization, has published recommendations specific to operating building heating, ventilation and air conditioning (HVAC) systems during these circumstances. Along with upgrading filtration to MERV 13 or better, ASHRAE recommends consideration of increasing outdoor air and adding ultraviolet germicidal irradiation (UVG)) as ideal ways to optimize indoor commercial environments[1]. Drawing on the expertise of ASHRAE can help you enhance your indoor space with confidence.

Increase Outdoor Air Ventilation

When possible, ASHRAE recommends operating your HVAC systems with 100-percent outdoor air to avoid recirculation. This can generate significantly more fresh air than codes require. Over a decade ago, for example, a Fortune 500 multi-brand restaurant operator adopted an approach where volumes of conditioned outdoor air are brought into the dining areas and transferred back to the kitchen as replacement air, giving its restaurants an advantage in higher outdoor air change rates in the dining areas. 

The outside air units pre-treat the dining rooms and kitchens to improve energy use and comfort in most of their restaurants. This design “over ventilates” the spaces as compared to typical restaurants, resulting in more fresh outside air and less recirculated air. The two chains provide an average of 125 percent to 180 percent more fresh air to their dining rooms than required by code while saving energy over more traditional restaurant HVAC designs and achieving a high level of comfort

During moderate weather, your existing HVAC system may be able to more easily maintain desired indoor temperature and humidity conditions by utilizing fresh or outdoor air economizers. Of course, using 100-percent outdoor air will require the ventilation system to have sufficient cooling, dehumidification, heating, and humidification capacity to properly condition this excess outdoor airflow during extreme weather conditions. If additional capacity cannot be provided to achieve this, the controls could be adjusted to maximize ventilation whenever possible, without sacrificing acceptable temperature or humidity control in the building.

Consider UVGI, Properly Implemented

Either because increasing outside air ventilation is not feasible or because they want to add to another layer of protection, some restauranteurs also are finding that what is old is new again: they are turning to UVGI.

UVGI, first demonstrated to disinfect water nearly 150 years ago back in 1877[2], is proving a successful tool in optimizing restaurant environments. Hospital administrators used UVGI to eliminate tuberculosis from hospital exhaust air back in the 1950s.[3] A 2010 Public Health Report on the history of UVGI for air disinfection reports, “The results of these studies confirmed both that TB could readily be spread through droplet nuclei and that UVGI could sufficiently inactivate the infected air (100% in the study).[4] The CDC has since published specific guidelines addressing UVGI for tuberculosis infection reduction.[5]

For an indoor environment such as a restaurant, ASHRAE recommends installing ultraviolet lamps in either the ductwork, air-handling equipment, or the upper region of the room[6]. The effectiveness of UVGI at reducing the presence of microorganisms depends on the intensity of the UV-C wavelength and the duration of exposure.

Just as a novice chef and a world-class chef use the same recipe ingredients with vastly different results, successful UGVI implementation in a restaurant requires a knowledgeable, skilled, approach. It is critical to engineer UVGI use to optimize performance and help ensure safety.

Therefore, it is crucial to identify a skilled partner such as an experienced energy service company to help you identify the appropriate UVGI efficiency rate for your restaurant and determine the number and type of lamps needed. Lamps installed will require a higher intensity than is used to clean cooling coils and drain pans (often called surface treatment). This is because surface treatment applications benefit from continuous exposure to the UV-C.

When trying to reduce the presence of microorganisms in a passing airstream, the duration of exposure is shorter, so a higher intensity of UV-C is needed. The UV-C wavelength can be damaging to some materials, particularly plastics and gaskets used in air-handling equipment, so proper shielding is needed to prevent direct exposure. Also, UV-C can be damaging to eyes and skin, so the application requires careful attention to protect service personnel.

Ideally, the energy service company’s system design engineer can calculate the Wells-Riley rate — used to identify infection probabilities in an occupied space — to determine how you can most effectively use UVGI.

For example, the Wells-Riley equation successfully predicted a measles outbreak in a suburban school in the United States[7]. The equation and its improvements also have been widely used to predict outbreaks of airborne infections and even to study the association between sick leave and ventilation system[8]

Take a Full IAQ Approach

Along with enhanced filtration, increasing outdoor air and adding UVGI technology, properly implemented for your space, are two steps to consider as part of an overall approach to optimizing your restaurant environment.

Learn how you can undertake a complete process to optimizing your indoor air quality in our recent Engineering Newsletter highlighting ASHRAE recommendations for COVID 19.

Learn more about UVGI solutions for your restaurant.

DISCLAIMER: The transmission of the SARS-CoV-2 virus, which causes the COVID-19 disease, may occur in a variety of ways and circumstances, many of the aspects of which are currently not known. HVAC systems, products, services and other offerings have not been tested for their effectiveness in reducing the spread of the SARS-CoV-2 virus, including through the air in closed environments.

[1] ASHRAE Epidemic Task Force Building Readiness, Updated 5-5-2020, file:///C:/Users/iicih/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/RYBU39U4/ashrae-building-readiness.pdf

[2] Reed, Nicholas G., Public Health Reports, “The History of Ultraviolet Germicidal Irradiation for Air Disinfection,” 2010 Jan-Feb; 125(1): 15–27.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789813/

[3] Reed, Nicholas G., Public Health Reports, “The History of Ultraviolet Germicidal Irradiation for Air Disinfection,” 2010 Jan-Feb; 125(1): 15–27.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789813/

[4]Reed, Nicholas G., Public Health Reports, “The History of Ultraviolet Germicidal Irradiation for Air Disinfection,” 2010 Jan-Feb; 125(1): 15–27.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789813/

[5] Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, “Environmental Control for Tuberculosis: Basic Upper-Room Ultraviolet Germacidal Irridation Guidelines for Healthcare Settings,” June 2009

[6] ASHRAE Position Document on Infectious Aerosols, updated 14 April 2020, www.ashrae.org/covid19

[7] Riley EC, Murphy G, Riley RL. Airborne spread of measles in a suburban elementary school. Am J Epidemiol. 1978;107(5):421-432. doi:10.1093/oxfordjournals.aje.a112560

[8] Qian, Hua; Zheng, Xiaohong. Journal of Thoracic Disease, Volume 10, Supplement 13, “Ventilation control for airborne transmission of human exhaled bio-aerosols in buildings,” School of Energy and Environment, Southeast University, Nanjing 210096, China, July 2018,

http://jtd.amegroups.com/article/view/18723/html_1