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folder Ventilation

Let’s talk about ‘fresh’ air?

Building managers should urgently review the way their ventilation systems are operating in light of the new restrictions announced by the government, according to BESA chief executive David Frise

BESA chief executive David Frise

The issue of air quality in commercial buildings has received widespread media coverage including a feature on BBC News, which advocated workers refusing to enter “stuffy” offices as these were most likely to pose a risk of a second spike in COVID-19 infections.

The work of building engineering services firms will continue to be crucial as we move into the colder months and continue to grapple with the virus. BESA has been advising members of the public, contractors and end users throughout the pandemic period with a consistent message to maximise the amount of outside air being introduced to buildings to dilute the airborne viral load.

Ventilation systems should be correctly set to maximise the amount of air being brought into the occupied spaces and should be regularly maintained.

The Association recommends that systems are run for longer and at higher speeds than normal – starting two hours before occupation and kept running at lower speeds overnight and at weekends to purge the building.

Of course, this will increase the amount of electricity consumed, but health is more important than energy efficiency right now. The key task of the HVAC system is to keep up air change rates – even in partially occupied buildings – to minimise the risk of transmission of the airborne virus.

Eventually, we will be able to return systems to their low energy modes, but for now some of our sustainability concerns must be on hold.


For now, systems that recirculate the air to improve energy efficiency should be switched to ‘full fresh air’ mode to minimise the risk of contaminated air re-entering the building. Recirculation dampers can usually be switched off manually or by using electronic controls. Return air from air handling units should be minimised and ‘purging’ carried out to avoid air moving from the extract side to the supply side of these units.

The lowest carbon emitting ventilation method is the ‘natural’ approach i.e. opening windows.

However, it is not a good idea to rely on that despite the fact that is what the BBC recommended. If there is little or no wind, the air will not naturally flow into a building from outside particularly if the temperature outside is colder than inside. In that case the air will flow out rather than in; so even less supply air is available to the occupants.

Another problem with opening windows is the risk of increasing the amount of polluted air entering the building, particularly in urban areas. There is a big difference between outside air and ‘fresh’ air. Bringing in outside air may create other risks to health if it is full of pollutants. It needs to be filtered and air purification technologies could be used in some circumstances. The latter have been proving their worth in healthcare settings.

Another issue to consider is when offices have been re-configured to allow for social distancing with desks moved and partitions erected. This will change the way air moves around the space and, therefore, needs to be taken into account when reviewing whether the ventilation is still fit for purpose.

For all of these reasons it is, therefore, important to ensure mechanical ventilation and air conditioning systems are working as intended and are well maintained. Filters should be regularly checked and cleaned or replaced and maintenance staff should wear full protective clothing, gloves, respirators and goggles when carrying out this work.

Well maintained ventilation systems will play a critical role in reducing any future spread of the virus, but some news channels have also tried to imply that air conditioning is a source of contamination.

Some referred to a study that examined a COVID-19 outbreak at a restaurant in China that was blamed on an air conditioning unit. However, it is simplistic to suggest this means mechanical building services systems pose a risk to occupants.

On the day in question, that particular restaurant was packed and its extract system used to remove stale or contaminated air was out of use. The only extractor was a small toilet fan at the opposite end of the room from where the diners were seated. The unit blamed for the spread was one of four units in operation and nobody close to the other three picked up the virus.

This was a flawed study that raised more questions than answers and the truth is that properly maintained air conditioning and ventilation systems can reduce the risk of a second wave by avoiding stale or stagnant air building up indoors.

However, if systems are not well looked after and/or there is no overall strategy for maintaining good indoor air quality, then there could be problems.

BESA Conference goes ‘virtual’

The crucial nature of the sector’s work will also be the main focus of next month’s BESA National Conference, which has moved to an online platform this year and will take place on November 4 and 5.

As well as topics linked to the health and wellbeing of building occupants, the Conference will look at most aspects of interest to building services professionals.

The free to attend event aims to build on the success of BESA’s series of daily webinars that kept the industry updated on commercial, business and health & safety developments throughout the COVID-19 crisis. These were a huge success reaching an audience of more than 20,000 between March and August.

With discussion topics spread across a main digital auditorium and a series of smaller virtual seminars, there will be content to suit all building engineering interests. Delegates will even be able to ‘network’ in specially designated areas and there will be a virtual exhibition hall to showcase the latest products.

BESA is gathering an impressive line-up of highprofile speakers including the return of World Health Organisation advocate Rosamund Adoo Kissi-Debrah.

Last year her inspirational session on the links between air quality and child health was heavily oversubscribed; and she is returning to update the industry on legal and political developments – and to exhort it to step up its efforts to turn buildings into ‘safe havens’ from air pollution.

There will be a series of plenary presentations covering topics from the impact of government rebuilding plans to new building safety legislation.

The Future of Cities, training and skills linked to the need for improved diversity in the building engineering workforce will also be under scrutiny.

These will be complemented by a series of technical sessions drilling down into the detail of developments in heating, ventilation, air conditioning,

refrigeration, indoor air quality, fire safety and smoke control, digital systems, off-site manufacture, ductwork and pipework – including updates on industry standards and best practice guidance.

There will also be tailored business seminars to help firms capitalise on the economic recovery and ‘BESA Clinics’ providing support and advice for members from the Association’s technical, legal, commercial, employment and health & safety teams.

“The availability of so much information online has made it harder to attract people to physical conferences in recent years,” said BESA President Neil Brackenridge. “However, BESA members and our industry partners have always seen the value of being ‘in the room’ to catch that important discussion and secure that nugget of information you wouldn’t have known about without actually being there.

“This year we have the chance to trial a ‘hybrid’ version using a highly sophisticated virtual platform that will replicate many aspects of a real life conference online,” added Brackenridge. “It promises to be an amazing experience and a vital couple of days for the immediate and long-term future of our industry.”

Although the conference is free to attend, BESA is asking attendees to make a contribution to its recently established IT poverty fund. This seeks to address the problem many young people have in

accessing laptops and tablets so they can learn the skills and competencies needed to join the building engineering industry.

BESA has found that the COVID-19 lockdown and the need to learn from home exposed the scale and complexity of this issue. Therefore, all conference donations will go towards a project to collect, refurbish and distribute IT equipment to young people in the industry who are in need.


8 October 2020


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