AIR CONDITIONING & AIR QUALITY Come clean and improve indoor air quality
Buildings need to breathe just as humans do, cue ventilation strategies, in particular the role of diffusers and grilles, according to Ian Rogers, sales director at Gilberts of Blackpool
T
he Government plans to build 1.5m homes over the next five years1
.
With limited land availability, we are increasingly building tall - now, almost 22% of home are flats2
data available, 44% of new homes are apartments3
almost 600 buildings over 20 storeys high currently under construction4
. According to the latest . In London alone, there are .
It’s therefore an area we as an industry need to address, to ensure everyone living there has suitable air to breathe. Air that is clean, and properly supplied throughout the building, in every dwelling, in every common part, communal area, and every stairwell. We think about the method of HVAC- MVHR,
PIV, air conditioning, fan coil, CAV, VAV etc. It’s all very well to ‘tick the box’ in getting fresh air into the home. To minimise the risk of damp and condensation – especially as homes are built to today’s high standards of insulation and airtightness with no fortuitous airgaps – we also need to consider air paths, and air flow. We need to be sure we get the air where it is needed, in the volumes it is needed – all without draughts and without wasting heat and energy. It is becoming more crucial, as rising energy costs lead people to keep windows shut, thinking that opening them lets the heat out. Your average Joe does not appreciate that a building needs to breathe just as much as a human does. That’s where ventilation diffusers and grilles come into play…. So often, they are not included on the specification: when did you last see an architect’s CGI showing grilles and diffusers? Or a detail drawing with specific types of grilles beyond ‘supply’ or ‘extract/exhaust’ annotated? It comes down to us as building services specialists- consultants, engineers, installers and manufacturers- to devise a solution to whatever challenge is before us.
Each space within the apartment block has its own diverse requirements which will influence the choice. Just by our daily living in our homes, we generate litres of water vapour- from breathing, cooking, washing etc. Figures vary from 400g (l) to 2.5l/person, but even taking the conservative estimate, that’s a lot of moisture that needs to be controlled and extracted to maintain indoor air quality. In communal areas, the air quality is massively
influenced by the activities occurring within the space- whether a café area, gym, reception, stairwell. In the café there is the risk of cooking odours, the gym will have high moisture levels from the sweat of exercise, reception could be exposed to draughts through opening doors, stairwells are in effect a chimney stack…. The grilles and diffusers need to be chosen to effectively deal with the specific issues in each zone, to maintain the determined indoor ambient temperature, velocities and acceptable C02 and noise levels. Building Regulations Approved Document F determines the number of air changes per hour. It is wise to cross reference with CIBSE Guide B2 Ventilation and Ductwork. Whilst that will address the amount of clean air within the space, you then need to consider the use of the space and positioning of the grilles and diffusers to maintain comfort conditions, not just across the space but in relation to each other, bearing in mind the air velocity will decay over the length of the air throw. It does help in these calculations that with many diffusers, the vanes can be adjusted to affect the air direction. There is an added consideration that there may well be an interior design architectural theme. Depending on client requirements, the grilles and diffusers can be selected to either be virtually invisible, or to enhance the interior aesthetics. With today’s modern manufacturing techniques, it is increasingly possible to personalise the grilles and diffusers beyond the specified colour palette: special finishes- stone and metal effects- can be added, face plates can be reproduced with corporate branding. And there are the day- to- day practicalities- within our range of swirl diffusers for example are options that are ideal for kitchens as they can be wiped clean.
Enhancing the interior goes beyond the décor: strategic slot diffusers in the ceiling in front of expanses of glazing ‘wash’ away any moisture/ condensation allowing full appreciation of the
14 BUILDING SERVICES & ENVIRONMENTAL ENGINEER FEBRUARY 2025
exterior view; they can be used vertically in the walls to form an invisible curtain of air to minimise the impact of cooler external air- and airborne pollutants- entering the building every time the main door is opened- important to maintain the indoor air quality. Often too we have to address idiosyncrasies within the building design- bulkheads are just one example. These can be turned to your advantage, providing a great site for, at high level, linear slot diffusers for supply or return air functions. And in the drive to reduce energy and
promote health & wellbeing (in which air quality plays a vital role), diffusers are being developed that are thermally adjustable, that rely on temperature sensitivity to automatically adjust the airflow up or down to maintain the preset ambient temperature without stratification or ‘cold dumping’- all without any electrical connection or energy use and whilst ensuring the occupants are consistently comfortable. We are all aware from our own lives of the
growing impact of design and form in our enjoyment of a space. With a little thought there is no reason why the style we admire in commercial premises cannot figure within our domestic lives. Grilles and diffusers are functional, but they are also increasingly aesthetic. They improve the IAQ. They also improve the IEQ (indoor environmental quality).
(1)
https://www.bbc.co.uk/news/61407508 (2)
https://www.ons.gov.uk/
peoplepopulationandcommunity/housing/ bulletins/housingenglandandwales/ census2021#:~:text=In%202021%2C%20 21.7%25%20(5.4,(4.9%20million)%20in%202011.
(3)
https://www.planningresource.co.uk/ article/1403328/44-new-homes-flats-survey-finds
(4)
https://www.standard.co.uk/comment/ acton-london-development-tall-
buildings-b1157688.html
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