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folder Ventilation

A very healthy debate

The public perception of building engineering services has changed dramatically because of the COVID-19 crisis, according to a range of speakers who took part in the 2020 BESA National Conference.

The two-day conference, which was held online for the first time and attracted over 1,000 registrations, was addressed by more than 60 speakers and panellists – many of whom focussed on the growing public awareness of the industry’s efforts to protect the health and wellbeing of building occupants.

For example, BESA members were urged to recognise their potential role as “physicians of the future” by an international authority on virus transmission. A range of other speakers highlighted the importance of mechanical ventilation systems in dealing with the UK’s multiple health and wellbeing problems – not just the immediate virus threat, but in the longer term too.

The safety of people in buildings was another hot topic with keynote speaker Dame Judith Hackitt once again reminding the industry of its responsibilities ahead of the publication of the draft Building Safety Bill.

She also appealed to the industry’s better nature by asking business leaders to reflect on the “shameful legacy of regulatory failure” that had left people “stuck in apartments that have become like prisons” due to poor quality work and safety breaches.


“People choose to live in high-rise blocks because we are a crowded island, and those people deserve to feel safe. We owe it to them,” she said in conversation with BESA chief executive David Frise. “If your elderly mum or granny lived in one of these buildings would you be happy about that? If not, then change.”

She congratulated the sector for the way it had dealt with the COVID pandemic; adding that it proved the industry could change its working practices if it wanted to. “So, if you can do it for one reason you can do it for another,” Hackitt said.

Delegates also heard that the industry had a responsibility to help support the UK’s ‘indoor generation’ of vulnerable children spending 90% of their time inside buildings. Many suggested the current advice to schools and other public buildings that they should open their windows to deal with the coronavirus pandemic was inadequate and likely to be ineffective.

Ventilation systems that manage air change rates, filter outside air and control both temperature and humidity would also be increasingly important as the country learns more about the airborne nature of COVID-19 and other viruses, delegates were told.

“Opening windows will not give you the air movement you need…it will just make you feel cold,” said BESA Health & Wellbeing in Buildings group chair Nathan Wood during a plenary session.

The Government’s SAGE advisory group has called for a national strategy on building ventilation backed up by research from Cambridge University recommending the use of displacement ventilation systems to reduce the concentration of virus particles inside buildings. 

They have also advised that air change rates should be adequate to keep carbon dioxide levels below 800 parts per million, which would not be possible with ‘natural’ ventilation, according to several conference speakers.

BESA Ventilation Group chair Tim Hopkinson said these developments were moving the ventilation industry into “uncharted territory” as its work comes under intense scrutiny. “We are getting belated recognition for the vital role the industry has always played in the health and wellbeing of building occupants – and ventilation is now seen as a key weapon in the battle against COVID-19,” he told the conference.

World Health Organisation (WHO) advocate Rosamund Adoo Kissi-Debrah added that there was still widespread ignorance about indoor air quality (IAQ), but she was more optimistic about the country’s ability to improve conditions inside buildings than she was about efforts to tackle external pollution.

“People would be surprised if they only realised how much control they can have over their indoor conditions. That gives me hope,” she said.

Luke Levens of Aspen Pumps reported growing demand for his company’s services to remove unpleasant odours from air conditioning systems and to tackle the problem of filters becoming breeding grounds for all manner of viruses.

“People are continually shedding skin cells, which end up in the filters. It is really important – particularly now – that we follow a process of clean/kill/protect,” he said.

The importance of controlling relative humidity (RH) was also stressed by Dr Stephanie Taylor from Harvard Medical School, who said it was key to tackling COVID-19 and in preparing buildings for future pandemics. 


She said managing the indoor environment was “the best medicine for treatment and prevention” and dubbed building professionals as the “physicians of the future”.

The ASHRAE Distinguished Lecturer said numerous studies had identified an RH ‘sweet spot’ between 40% and 60%. Air that is too dry will allow viruses to thrive and be more active, she added. 

“We need to start regarding human health as a key measure of success for our buildings,” said Dr Taylor; adding that RH should not be sacrificed to reduce energy use. She also presented compelling research results from around the world that COVID-19 becomes “more prevalent and more virulent” in dry air. 

“As we speak, we expire droplets out of our airway about 100 microns in diameter. When they enter the air in the room, those droplets shrink according to the RH of the ambient air. If humidity is maintained between 40% and 60%, the droplets shrink to a point where studies show the concentration of salts in those droplets inactivates microbes that are being carried in the droplets.”

However, if RH is less than 40%, those droplets shrink even further and the salts preserve the microbes, making them more virulent. “One study at a pre-school showed that humidification decreased flu infections. In fact, it showed that dry air causes infections,” said Dr Taylor. 

Other research has also shown that in low humidity indoor environments, the human body has difficulties fighting off infections – compounding these problems. 

A US study looked at higher flu infections in dry environments. It found that at 50% RH, the human immune responses function well. But at 20% RH the body cannot defend itself from microbes as effectively. 

COVID-19 is not the only illness that thrives in our modern air-tight and heated environment. There are also increases in inflammatory disorders, auto-immune disease, and allergies. Dr Taylor emphasised that there can be no doubt that the indoor environment is in the front line in the fight against future pandemics. 

“As a physician I’ve come to realise that managing our indoor environment is the most powerful medicine both for treatment and prevention. The corollary of that is that building professionals really, in my opinion, are the physicians of the future.”

However, the quality of ventilation installation, particularly in homes, is a growing area of concern, according to several conference delegates. BESA’s head of technical Graeme Fox said mechanical ventilation with heat recovery (MVHR) systems were being more routinely fitted in new homes that were being designed for energy efficiency and, therefore, made more airtight.

Many of these systems were fitted by plumbers and electricians who may not have the right qualifications or technical understanding of how they should work. Often, they were not properly commissioned and rarely maintained leading to serious problems with condensation and stale air. It was agreed that BESA should work with other like-minded industry bodies to address this problem as a matter of urgency.


Growing problems with legionella bacteria was another human health issue under the microscope during the BESA Conference.  Swiftclean’s David Randlesome said there was more legionella found in sampling procedures during the first long lockdown. 

“The symptoms of COVID-19 are very similar to Legionnaire’s Disease, so anyone showing symptoms is more likely to be tested for the virus and not for Legionnaire’s,” he added. “I would say that there’s a good chance that a lot of cases were there, but were not tested for.”

The industry can also be a source of reassurance to people reluctant to return to buildings because of health concerns, the conference agreed. One solution proposed was the creation of a ‘COVID-safe’ certification scheme that would display what measures had been taken to safeguard occupant health and wellbeing.

“This could also act as a reward for the most responsible building owners,” said Fox. “If you are spending more on your properties to make them better and safer, you should be able to tell people.”

It was also agreed that a baseline standard for IAQ was urgently needed so that building managers could assess what contaminants to measure and what action to take. 

BESA’s Health & Wellbeing in Buildings group reported to the conference that work was already underway to produce a ‘Layman’s Guide to IAQ’ that would prove equally useful to both non-technical building managers and highly qualified professionals designing ventilation systems.

BESA President Neil Brackenridge said the decision to go ahead with the conference despite the obvious difficulties had been vindicated. 

“There were plenty of reasons for us not to stage a conference this year. I don’t think anyone would have blamed us if, given the circumstances, we had decided to keep our powder dry until next year,” he said. “However, BESA has a hard-won reputation for providing leadership in times of difficulty and keeping our members – and the wider industry – informed when information is crucial.

“So, we didn’t really hesitate, and that decision was surely vindicated by the attendance and the fact we attracted an incredible range of expert speakers – more than 60 in total.”

He added that the need for business, technical and health & safety advice had never been greater. “However, it is equally important that we are able to come together as an Association and a sector to share our concerns and work together on solutions,” said Brackenridge.

To review the conference sessions, go to:

10 December 2020


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