NATIONAL REPORT—In the hospitality industry, nearly all of the upgraded health and safety protocols created in response to COVID-19 mention some change in the ventilation system. So, has the pandemic changed the future of HVACs?
“People are scared they might get the virus if they visit a hotel,” said Blair Hildahl, principal for Base4, an architecture and engineering design firm.
Michael Driedger, co-founder/CEO of Operto, a provider of property automation software for hotels and vacation rentals, noted that priorities for hoteliers have moved from saving energy—which often means recirculated air—to increased ventilation “while also considering humidity and filter maintenance.”
Chuck Hurchalla, president of energy management, engineering and consulting firm Evolution Energy Partners, noted that the American Society for Heating Refrigeration and Air Conditioning Engineers (ASHRAE) released recommendations applicable to large hotels regarding dilution ventilation—the process of decreasing the concentrations of indoor contaminants by diluting spaces with outside air.
The recommendations include opening outdoor air dampers to 100% (as indoor and outdoor conditions permit); disabling demand control ventilation and energy recovering systems; enabling outside air economizer mode and increasing minimum outside air settings; maintaining relative humidity between 40% and 60%; checking airflow to larger areas; maintaining proper pressurization (both building pressure and toilet exhaust); and air flushing the building two hours in the early morning and late evening every day. This includes operating the exhaust fans and opening the outside air dampers.
Hurchalla said that even though smaller hotels have different kinds of HVAC systems, they can still heed some of ASHRAE’s advice.
As a result of the concerns surrounding COVID-19, many hotels will look to upgrade their filtering systems, adding HEPA (High Efficiency Particulate Arrestance) filters, or using filters with higher MERV (Minimum Efficiency Rating Value) ratings.
“Filter efficiency—a filter’s ability to capture particulate matter—is determined by its MERV rating. Because COVID-19 is 0.125 microns, we will focus on filter efficiency at the 0.03 to 1.0 microns level,” said Hurchalla. “A MERV-8 filter—the minimum standard filter for commercial office buildings—will trap less than 20% of air particles size 0.03 to 1.0 microns, whereas a MERV-16 filter, the common minimum standard used by hospitals, will capture 95% or more.”
A HEPA filter has a MERV-16 rating. According to Driedger, it can likely catch most viruses as indicated from the research thus far. “However, you can’t just put a HEPA filter in rather than a MERV 10 because it will get clogged very quickly with dust,” he said. “It is also very expensive to have to change them often. Usually, there is a lower MERV rating filter in front of the HEPA filter to catch dust.”
Hildahl suggested the use of MERV-17 and MERV-13+ filters, especially in large public spaces and in back-of-house areas, adding that hotels should “provide Ultraviolet Germicidal Irradiation (UVGI) with possible in-room fans in the guestroom or UVGI lights in the HVAC systems (UV-C) in upper rooms. These systems use ultraviolet light to help kill viruses and organic growths.”
Hurchalla noted that the three most prevalent approaches to UVGI are installing them near the primary AC coil or, for smaller hotels, in the air ducts; installing the lamps into fixtures suspended from a ceiling or mounted on a wall (for an upper-room UVGI system in lobbies, conference rooms and back-of-house areas); and using mobile UVGI room sterilization, where multiple lamps are affixed to a mobile unit on wheels or driven by pre-programmed robotics.
“Many hotels are now using mobile UV specially designed to fit on housekeeping carts,” he said. “In this scenario, a housekeeper will have two carts outfitted with UV. When done cleaning a guestroom, the cart is left in the room and the UV lights are turned on. The housekeeper then cleans the next room with the second cart while the first room is being disinfected. The housekeeper then repeats the process in the second room and so on.”
Another piece of equipment that has been used by hotels to stop the spread of viruses is bipolar ionization technology. Architecture and construction firm LMi Designs also provides air-purifying services, which includes AtmosAir’s ionization system.
“The air moving around in a space has positive and negative charges, and what the ionization system does is manipulate that charge,” said Kevin Kouton, visual director for LMi Designs. “If a foreign object like bacteria or a virus is moving through an area when somebody walks through the front door and sneezes, the electric charge wraps around those molecules and brings it down to the floor, killing it. The minute people walk into the space, anything on their clothing and anything they touch, it’s all being sterilized.” HB