52
feature
heating, ventilation & damp proofing
the little things that make a difference
Ian Rogers, Sales Director at Gilberts Blackpool, looks at how care taken with HVAC
It is human nature to focus on the big picture. We can forget the impact the small things can make to the overall objective. Yet, especially in today’s drive towards energy efficiency and low/ zero carbon, they can make a difference. Ventilation grilles and diffusers are a perfect example.
How they move air – and therefore heat – within the building can impact significantly. It affects not just the demand made on the HVAC system but occupant comfort, after all, it’s normal that if someone is feeling cold, they turn the thermostat up. Yet, that cold could be because the grilles and diffusers have not been appropriately or correctly specified or positioned across the floor plan. It helps to understand how different strategies work. Traditionally,
we position our HVAC at high level, where we can conceal ducting etc behind/above ceilings. In recent years, there has been a trend towards exposed ceilings, which has impacted on the choice of air distribution units to maintain a comfortable and energy efficient internal environment. Physics dictates that air needs a surface to cling to i.e. the ceiling. Remove that surface and the air ‘dumps’
onto the occupants below. Most recently, there is a move towards under floor heating, in theory to address energy efficiency. The warmth is instantly deployed within the bottom 4-6ft of the interior – where the occupants are. Wherever the HVAC system is sited, the choice of air distribution unit affects the air delivery. At high level, swirl diffusers swirl the air supply, circling it in every
direction to mix quickly and thoroughly with the air already in the space. As mentioned earlier, the throw of the supply air is affected by surrounding surfaces: air flows along ceilings before gravity takes effect; if there is no ceiling, that incoming air has nothing to cling to so can ‘dump’ onto the occupants below. If too closely positioned, the incoming air buffets, causing turbulence and draughts.
Not only does that make the occupants uncomfortable, the air is not mixing effectively, making greater demand on the heating/ cooling system to maintain the preset ambient temperature. This is easily remedied by adding a Coanda plate to the diffuser.
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