SERVICE AND MAINTENANCE


would by default always ensure the designed ventilation rate is delivered, more so than recirculatory secondary cooling systems that can be run independently from the main ventilation system and so may not deliver adequate air change rates. We need to be careful when increasing


ventilation rates because this could come at a high cost if we simply increase our historic design figures by a given percentage. Larger ductwork and other services may lead to higher capital costs, less usable or lettable space, and of course higher energy usage. For these reasons Demand Controlled Ventilation (DCV) could offer a sensible solution by providing ventilation when and where it is necessary, based on the prevailing demand of occupancy or air quality, and avoid delivering air unnecessarily where there is little or no demand. We also need to be sure that the outdoor air we are bringing into the building is not simply replacing one contaminant with another, so suitable levels of filtration to guard against pollutants such as pollen and NO2 should be a prerequisite. Secondary filtration inside the building on recirculatory cooling or heating devices is a more complicated issue. These can have coarse filters that do not filter smaller particles, but may still collect potentially contaminated particles which may then be released when fans start to operate.


Managing indoor environments At last year’s BESA National Conference, 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 health challenges. 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 Taylor; adding that RH should not be sacrificed to reduce energy use. “We need to get that balance right.” We have also had another stark reminder of why we should be highly motivated to deliver the very best indoor environment: Late last year, Ella Kissi-Debrah became the first person


www.acr-news.com


in the world to have air pollution officially listed as a cause of death following a landmark ruling by the coroner presiding over a second inquest into her case. He ruled that air pollution "made a material


contribution" to the nine-year-old’s death in 2013 following a series of severe asthma attacks. Coroner Philip Barlow said Ella had been exposed to “excessive” levels of air pollution and that levels of nitrogen dioxide (NO2) near her home exceeded World Health Organisation (WHO) guidelines. This historic ruling has prompted a campaign to create ‘Ella’s Law’ that would replace outdated clean air legislation; including the need for more focus on the quality of the air inside buildings to protect children’s health, in particular.


Poor air quality is thought to contribute to


the deaths of up to 36,000 people in the UK every year and over seven million worldwide, but Ella is the first person to have it stated on her death certificate. Research carried out by Professor Stephen Holgate at Southampton University, which showed that indoor air quality (IAQ) can be 13 times worse and more concentrated than the outside pollution, was cited during the inquest. Ella’s mother Rosamund, who led a seven-year campaign to achieve this ruling, is now a powerful advocate for better IAQ control and legislation. As we look to emerge from the current crisis, the role of ventilation in reassuring people that buildings are safe and can, in fact, protect them from some of the worst threats in the outside air could play a crucial role in getting our country moving again and returning society to normal.


May 2021 27


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