BSEE-MAY21-P20 Waterloo_Layout 1 19/04/2021 13:45 Page 20


BSEE


Improving ventilation to tackle airborne viruses and improve the quality of the indoor environment can also have a positive impact on your bottom line, says Waterloo’s Russell Shenton. There are obvious healthcare and social welfare reasons for investing in improvements to the indoor environment quality (IEQ), but there are also strong business reasons for taking this seriously.


O Control


“We don’t yet know how much ventilation we need to get things under control; we might never know that,” said Cath Noakes, Professor of Environmental Engineering for Buildings at the University of Leeds. “We know it [ventilation rate] matters and will be critical for health and wellbeing beyond Covid so we must get this right.”


“We can say 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 regulations that will help, but we may need to go beyond that,’ she added. Professor Noakes said that recent studies suggested some of the larger water droplets that carry the virus can be suspended in the air for longer by air conditioning and cautioned against using it in places with low levels of ventilation. She also said air cleaning was not a reason to ventilate less, but “should be used where you can’t ventilate effectively”.


She has advised the government that 10 l/s is the ideal, but if people are close together and for an extended period that may have to be increased. Similarly, lower ventilation rates may be fine for larger numbers of people if the space is bigger. “The spaces that worry me the most are those that are naturally ventilated as these are temperature and wind dependent…some buildings have no proper ventilation at all,” added Professor Noakes. Our understanding of the role of relative humidity (RH) is also improving because of closer focus during the pandemic. This issue has been widely ignored in the past but is now gaining the recognition it deserves for playing a key role in establishing good IEQ.


AIR CONDITIONING, COOLING & VENTILATION


Ventilate for healthier people, better buildings, and bigger profits


ur understanding of how viruses are transmitted inside buildings has improved rapidly during the pandemic and has led to greater focus – not just on increasing ventilation rates, but


also looking closely at the path taken by the air. However, the lack of mechanical ventilation in many buildings has left facilities managers with no option other than opening windows.


While this offers some protection, it is rarely a complete solution because it does not guarantee the recommended minimum air change rates of eight litres per second per person (8 l/s). It will also leave stagnant unventilated pockets in a room and enable unfiltered air to enter the occupied space potentially carrying harmful outdoor pollutants. Keeping CO2 concentrations below 800 parts per million is a good indicator that the ventilation strategy for the indoor space is working. However the Scientific Advisory Group for Emergencies (SAGE) has warned that simply increasing ventilation rates is not the answer.


Dr Stephanie Taylor from Harvard Medical School believes RH should be measured and addressed to help protect building occupants from future health threats. The ASHRAE Distinguished Lecturer said numerous studies had identified an RH ‘sweet spot’ between 40% and 60% adding that air which was too dry would allow viruses to thrive and be more active. She added that RH should not be sacrificed to reduce energy use. “We need to get that balance right.”


However, current building standards still focus on a simple linear relationship between the outdoor temperature and indoor comfort temperature and there is no mandatory legal requirement to control RH. One positive outcome from the current crisis would be a long overdue change in this area because recommending high ventilation rates without counterbalancing that with RH control can lead to very dry indoor environments, which could have the perverse effect of creating conditions that actually help viruses to thrive.


In the cold, dry winters of northern Europe, indoor RH-levels can drop to 5-15% for extended periods, which is great for viruses, but not so good for people. If the humidity is too low, small particles are also more likely to be inhaled deep into lungs and infectious particles survive longer. If the RH remains below 30%, the skin becomes dry leading to itching, cracking, and chapping.


Allergic


On the other hand, if the humidity is too high, it encourages mould growth and bacteria that can cause respiratory problems and/or allergic reactions, including increasing the risk of asthma attacks. Very moist air will make people feel chilled in cold weather and hot and sticky in summer. Humidity also affects the performance of buildings, the durability of building envelope materials and the longevity of equipment. This has significant business implications and is one of the issues picked up in research carried out by the leading business organisation.


A study carried out by CBI Economics for the Clean Air Fund found that poor air quality reduces the productivity of staff, shortens the operating life of capital equipment and increases maintenance costs. It said that meeting World Health Organisation (WHO) air quality guidelines by 2030 should be part of the country’s plans for rebuilding the economy. “With air pollution hitting the balance sheets of businesses across the country, and cutting the earnings of their employees, cleaning up our air would help us to lead healthier and more productive lives, while delivering a green jobs boost for the economy,” said chief economist Rain Newton-Smith.


Waterloo Case Study – 55 Douglas Street, Glasgow


The transformation of a landmark office building in the centre of Glasgow has provided the city with much-needed grade A office space, using air distribution products by Waterloo Air Products Ltd. Working with M&E design consultants Hulley & Kirkwood, Waterloo became involved at the design concept stage of the development. “Waterloo’s product range always offers the high performance and quality that a project of this scope requires,” said Hulley & Kirkwood’s Technical Director Allan West. “But it is equally important to us to find products that are both adaptable and aesthetically sympathetic to our design plans. Waterloo’s proposed products were a perfect fit with the architect’s ceiling design aspiration, so everything could quite literally slot into place without any need for adaptations.” The primary requirement was for a diffuser to run around the perimeter of the building’s upper floors that would integrate seamlessly in terms of both fit and appearance with the two sizes of perforated steel ceiling tiles. Waterloo’s aluminium continuous linear slot diffuser (CS-F) was selected as the best product for this installation due to its industry- leading aerodynamic and acoustic performance. A further advantage was that Waterloo could supply a variation of this diffuser (CS-M) that would exactly match the smaller tiles.


Precise colour match was also an important consideration. Waterloo was able to provide the diffusers in exactly the same polyester powder coated RAL9003 paint finish as the tiles, which was very slightly different to Waterloo’s normal colour for this product. Virtually anything is possible with Waterloo’s extensive range of products and finishes.


Ceiling system manufacturer SAS International supplied Waterloo with the tiles and the CS-M slot diffusers were easily dropped into place thanks to the precise matching of the tile’s aperture with the diffuser’s dimensions. The combined tiles and diffusers were then delivered to the site, ready for installation.


For the latest Waterloo CIBSE CPD Webinars visit www.waterloo.co.uk/cpd-and-training 20 BUILDING SERVICES & ENVIRONMENTAL ENGINEER MAY 2021 Read the latest at: www.bsee.co.uk


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