Published on June 3, 2020 on LinkedIn by Paul Rigby
I guess we all remember the story about nine diners who contracted the coronavirus at a restaurant in China.
The news broke in January, and since then it’s been widely thought that it was the building’s AC system that boosted the disease’s ability to spread via airborne particles. Some researchers went as far as to recommend to switch off the ventilation systems completely. The war on the pandemic indeed depends greatly on HVAC systems. Public recognition of this fact can be seen in the US, where the Department of Homeland Security included our industry workers in its list of employees critical to the COVID-19 response. This significance is most evident in the case of healthcare facilities as they have become the central battlefield in this war.
The significance of HVAC systems in hospitals
Despite doubts around AC spreading coronavirus, hospitals can’t afford to shut down their HVAC systems. Heating, ventilation, and air conditioning play essential roles in medical facilities. Staff use them to manage climate conditions, such as temperature and humidity. Significantly, some HVAC equipment helps to protect patients and medical staff by providing germ-free environments to prevent the spread of diseases. Hospitals are complex facilities, so their HVAC systems operate zones to ensure that different parts of the building can be used for various purposes.
Circulation zones in healthcare
Medical equipment in healthcare facilities is frequently susceptible to humidity levels and temperature changes. These need set conditions to work accurately. COVID-19 sufferers require a level of isolation. Patients with weakened immune systems also need different rooms–from operating theatres to neonatal facilities and intensive care units. Here it is vital that patients don’t get in contact with the pathogens travelling in the hospitals’ air system and generally in higher amounts than anywhere else. This higher concentration of germs means that HVAC systems may pose a health risk.
Design and standards are key
While almost all HVAC systems will look at humidity and heat control, those in hospitals will also take special care with over- and under-pressure areas to allow zoning. All parts of the system must include the correct water and air tightness and clean elements. Elements that require maintenance must be accessible, and the system must have the right level of external air to operate properly. HVAC designers will look at the building’s classification to work out the correct filtration, using HEPA in the most exposed areas and possibly deploying biocide filters in lower-risk areas.
ASHRAE to the rescue
The industry has been working a long time to develop the correct standards. The most important come in the form of standards set out by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the healthcare sector Facilities Guidelines Institute (FGI). They provide figures for outside and total air changes, as well as the need to exhaust particular rooms fully. These parameters are set out in ASHRAE Standards 62.1 and 170. Standard 62.1 specifies minimum ventilation rates and other measures for new and existing buildings to provide acceptable indoor air quality that minimises adverse health effects.
Standard 170 ANSI/ASHRAE/ASHE offers guidance and mandates to designers of healthcare facilities with a focus on different zones, such as examination rooms, laboratories, and more. It also specifies requirements for higher hazard-exhaust airstreams.
Separating the air streams
Airtightness is a crucial aspect of fighting viruses like COVID-19, so choosing the right equipment should be high on our priorities list. This requirement also applies to heat recovery solutions. According to REHVA, it is usually plate heat exchangers that best accommodate this condition. For instance, a carefully designed, EN308-compliant counterflow heat exchanger can ensure the highest level of airtightness – just as the Swiss Rotors’ one does.
Responding to the new challenges
ASHRAE experts agree that disabling HVAC systems doesn’t stop the transmission of the virus. On the contrary, they state that ventilation and filtration solutions can reduce the airborne concentration of SARS-CoV-2. And in response to the outbreak, ASHRAE has issued guidance for the entire HVAC industry, including the systems used in healthcare. Their comprehensive update discusses a range of working practices and suggested approaches to improving airflow patterns, eliminating recirculation, using HEPA filters, and performing safe HVAC maintenance work. The organization also touches on the issue of heat recovery wheels. Its experts recommend preventing their contamination by utilizing HEPA filtration and discharging patient room exhaust directly outdoors instead of to the ventilator.
ASHRAE also suggests deactivating the wheel if it leaks air. This situation, in general, is less likely in wheels which–just as Swiss Rotors’ air-to-air exchangers–use a twin sealing system and purging sectors. I’m proud that our wheels by default stay well below the leakage level set in ASHRAE 61.2.
What are your thoughts on the ventilation of healthcare facilities amidst the pandemic? Please share your comments in the section below.
About the author: Paul Rigby, accomplished technical sales manager, and commercial director. With over 12 years of experience in the HVAC industry, he is in charge of Swiss Rotor’s business development in the USA and Western Europe.