www.heatingandventilating.net
INDOOR AIR QUALITY
I
t is a sad reflection that despite indoor air quality (IAQ) having been talked about for years, there is still no one, over-arching piece of legislation or
guidance as to how we address it. It is similarly concerning that, bearing in mind we spend 15- 20% of our time at work(1) and as a nation work longer hours than the rest of Europe, what research data does exist into the topic focuses on the domestic environments. And if we apply that, then the picture is not good: a government study in 2019 showed that nearly all new build homes measured did not meet the required ventilation rates set out in the Building Regulations Approved Document F(2). On a positive, the drive towards greener energy should have a positive impact on IAQ, in that we are not burning coal, gas. However, climate change is changing our environment(3): we’re getting warmer, wetter winters which means greater incidence of damp. We’re building tight, but we’re not ventilating
right. It matters: we can go without food for up to 3 weeks, without water for up to 3 days but without air- just 3 minutes(4). The key is to balance airflow, air temperature
and pollutant cumulation. But it’s more than that. Poor IAQ affects not just the people, but the building too: damp damages the building fabric, increasing maintenance costs. For us involved in the HVAC industry, we know
how hard it is to put rules of thumb in place. We can generalise about the airflow rates for a particular size of space but there are still the individual building specifics to take into account- its surrounding topography (particularly a consideration with natural ventilation), occupant behaviour, the number of electrical devices being used therein… Achieving good IAQ comes down to the detail: making sure airflow rates are correct, and as importantly, airflow is delivered where it is needed, and how it is needed. That comes down to the air delivery units (ADUs). The choice of ADU can itself impact significantly on the IAQ, on the where and how the air is delivered. For example, fixed swirl diffusers will deliver
high volumes of air with rapid entrainment and intermixing. Yet if they are sited too close together, the swirling air paths will collide and buffet, potentially transferring airborne pollutants. Their performance will be adversely impacted. Occupants
IAQ – it’s down to the detail….
Dave Harding, sales and marketing director at air movement specialist Gilberts Blackpool, explains why achieving good IAQ is all about the detail: ensuring airflow rates are correct, and just as importantly, that air is delivered where it’s needed and in the way it’s needed
air throw and create a more comfortable occupant environment. Multi nozzle diffusers enable more precise delivery
of air, with each nozzle capable of being individually rotated to smoothly supply air precisely where required without draughts. Precision is taken a step further by using a slot diffuser, creating in effect a smooth, accurate curtain of air. Where precise airflow is needed, especially in
large zones, a jet nozzle may be a better choice. Today we are fortunate in that we have a myriad of
will feel uncomfortable. Adjustable swirl diffusers provide extra flexibility in that the air supply can be directed horizontally or vertically. The latest evolution is a temperature- sensitive version which automatically adjusts the airflow direction to help maintain the preset ambient temperature should it vary. If whichever type of swirl is being used in an
exposed ceiling environment, the air can ‘dump’ onto the occupants as it has no surface to cling onto. Something as simple as adding a Coanda plate to the swirl at specification stage will help optimise the
software solutions to help us validate a design before committing. Using computation fluid dynamics (CFD) software, the proposed ventilation/ air movement design can be tested to validate its performance according to air changes, air quality, temperature. Appropriate adjustments can then be made to the strategy if required, and retested, to ensure the target performance criteria will be met once the ventilation is installed and the building occupied. From the IAQ perspective, CFD can be extremely
helpful, demonstrating air projection and drop, temperature and air mixing (heat transfer), and particle distribution. Obviously, ADUs are only a small part of the
overall ventilation/IAQ strategy but they are vital to its effectiveness, being the frontline controls. The choice is constantly changing. Work with manufacturers to make the best decisions and build on the opportunity.
https://standout-cv.com/stats/work-life-balance-statistics-uk
https://researchbriefings.files.parliament.uk/documents/POST-PB-0054/POST-PB-0054.pdf https://www.ukclimateresilience.org/news-events/climate-change-shifting-uks-high-impact-weather https://www.worldventil8day.com
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February 2026
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