VENTILATION SYSTEMS
Managing indoor air quality ‘themostpowerfulmedicine’
One positive outcome of the COVID-19 crisis has been the increased focus on improving the ventilation of indoor spaces, and the need to measure indoor air quality (IAQ). Steve Tomkins, head of Business Development at the Building Engineering Services Association (BESA), explains how the healthcare sector will benefit.
Ventilation has come blinking into the limelight because of the COVID-19 outbreak. For so long a ‘Cinderella’ service, it is now a topic of urgent discussion. Building managers are facing detailed questions about how they are improving airflows to help dilute airborne viral loads. While this has long been a key preoccupation for the ‘behind the scenes’ Estates and Facilities managers in healthcare properties, never before have these discussions come under such intense scrutiny. There is also a renewed focus on relative humidity (RH), because of growing evidence that viruses thrive when the indoor air is drier. While these issues are concerning Estates and Facilities managers in buildings up and down the country, their implications are markedly more important in healthcare settings, where many of the occupants have supressed immunity. There is also greater recognition that building engineering professionals are key members of the wider healthcare team – and that therefore greater significance should be given to them using all the planned maintenance tools at their disposal.
Vulnerable occupants
The importance of turning buildings into ‘safe havens’ that protect vulnerable occupants – particularly those suffering from respiratory illnesses – from rising air pollution outside, and other airborne threats to their health and wellbeing that thrive indoors, is also a key issue at government level. Professor Cath Noakes from the University of Leeds is a ventilation specialist, and one of only two engineer members of the Scientific Advisory Group for Emergencies (SAGE) that has been helping the Government navigate the pandemic.
She is determined that the industry takes advantage of this increased awareness to ensure that buildings are protected for the long term, so that after the current crisis has subsided, we don’t slip back into accepting poorly ventilated spaces with high levels of indoor contaminants.
One positive outcome of the COVID-19 crisis, BESA points out, has been ‘the increased focus on improving the ventilation of indoor spaces’.
Speaking at a recent webinar hosted by the Building Engineering Services Association (BESA), she said there was still much to learn about how ventilation can protect building occupants from viruses and other airborne threats, but that settling on a ventilation strategy was not straightforward. She said: “This is a very complex issue, and it will take years to build up the amount of data needed to make sure we can do this better. However, as a rule of thumb we should aim for [air change rates of] 10 litres per second (L/s) per person, and CO2 800 parts per million.”
concentrations below
Household transmission ‘a particular concern’
Professor Noakes confirmed that studies had shown the risk was higher indoors when ventilation provided less than 3 L/s
per person, and that household transmission was a particular concern. She also explained that the virus thrived in cool, dry, and dark conditions – making RH control a priority. However, this does not just mean ‘turn up the ventilation and let it rip’, but it does support the case for investing in some form of controlled mechanical system and maintaining it properly.
“We know that ventilation matters, and will be critical for health and wellbeing (including mental health) beyond COVID, so we must get this right,” Prof. Noakes told the BESA webinar. “We can say that we have not seen any evidence of high transmission in well-ventilated spaces – so if we are designing and delivering to the standards set in current building standards that will help, but we may need to go beyond that.”
September 2021 Health Estate Journal 17
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