Air distribution


www.heatingandventilating.net


Are the winds of change increasing in force in commercial building air distribution? Where once function, performance and price were the over- riding factors in the choice of air terminal devices (ATDs), today there seems to be growing pressure to add form into the mix. That’s the view of Ian Rogers, Gilberts Blackpool sales director


Swirl diffusers are the conventional solution. I


t’s a consequence of our changing working environments and philosophies, in essence, making our offices attractive places to be. It’s not just about companies being considerate employers: happy workers are more productive, and more loyal. Even details like the ventilation grilles and diffusers are now being considered as part of the overall aesthetic, for their impact on maintaining a comfortable atmosphere and on their integration into the interior design: designer preferences are now figuring in the mix. The challenge for building services is one of balance: that the ATDs maintain the indoor environmental quality (IEQ) – air volume, cleanliness and temperature – in a way that is energy efficient, and that compliments rather than detracts from the IEQ. After all, the ventilation is predominantly around where the occupants are. As we become more design- aware, we begin to notice details that previously we overlooked – that includes the ATDs. Form now registers. The trend for exposed ceilings continues and to an


extent has driven the focus on the aesthetics of ATDs: they are now front-of-field when one looks up, not something that blends into the suspended ceiling.


However, the physics of air distribution require a surface for the air to cling to, to avoid draughts and cold dumping, to optimise entrainment and inter- mixing. Exposed ceilings means there is no surface for the air supplied by the swirl diffuser to cling to. Coanda plates are a cost-effective and efficient way


of addressing that. As a rule of thumb, reinforced by physical testing and CFD analysis. providing enough distance for the exiting air to attach to the plate, achieve the coanda effect and move horizontally. Interestingly, the size of the coanda does not directly relate to the throw and extending it can actually makes little or no difference to the throw and overall performance.


With manufacturing technology advancements,


where it is easier and therefore more cost-efficient to produce bespoke options in small runs or one-offs, the coanda can become an integral part of the interior design palette. We’ve had requests to make diffuser coandas that look like records, that are primary colours, metallic, transparent or translucent. No longer are they always metal:


The changing face of air distribution


they can be almost any solid material: acrylic sheet is one option, that can then be back-illuminated. Irrespective of where the ATD is being fitted


– exposed ceiling, suspended ceiling, wall – the end aesthetics matter more than in the past. Manufacturing processes – powder-coating, foiling, punching – enable the aesthetics to be delivered. Form is not confined to colour or type of finish. ATDs are now being designed so that the unit is itself aesthetically pleasing – fineline linear bar grilles, shadowline diffusers where the blades appear to be floating in space, frameless or plaster-in flange ATDs almost disappear into the structure… Faceplates whereby the diffuser


impeller is concealed (without impacting performance) are now popular. The capability to produce small runs means the faceplate can be individually designed, styled to compliment the


overall design of the space, rather than detract from it by a purely functional appearance. The ability to add a faceplate to a swirl diffuser also extends is usage, into almost any ceiling type. Form is not confined to linear. Manufacturing


advancements mean arcs can be cost-efficiently constructed and installed. Where we are all striving to deliver good quality


built environments, we must not lose sight that form is important, as well as function. None of these aesthetic elements make any change of consequence to the overall price of the job. Nor do they impact on the way you normally work in selecting the ATDs for a project, nor particularly on installation. But they take it to a new level, a new dimension. They make a significant change to the overall success of the install in delivering the quality, the desired “look”, “feel” of the internal space, the IEQ.


16 January 2024


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