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circulation pump. The combination makes it a highly attractive proposition for schools. Conscious of the wider constraints architects face in designing the school building to modern criteria, as manufacturers we also take into account air leakage and thermal performance in the solutions. However, for a whole raft of factors, natural ventilation or its variations are not always practical or feasible in the diverse environments we find in schools – the open space of sports halls, the high heat level in ICT suites, the possible pollutants in science labs.


Architects and


manufacturers need to work together in order to develop practical, cost- effective solutions


health and wellbeing perspective too. Because you are constantly drawing in fresh air from outside to ventilate the internal space via planned air paths, rather than using reconditioned air, the incidence of sick building syndrome is minimised. Hence we are seeing a growth in the use of hybrid evolutions such as the inclusion of heat recovery (HV-HR) and a move towards zoning, decentralising the ventilation systems to create a number of stand-alone units without a big, central plant room installation. ‘Hybrid’ because, although predominantly using natural ventilation, designers, manufacturers and consultants appreciate that there are times when we need to supplement extraction (purge) beyond what the prevailing weather outside is capable of delivering; a boost is needed, which is provided by the incorporation of a low energy fan. On average, most HV-HR systems can only achieve heat recovery of around 40%. It is possible to achieve more: some systems have been proven to achieve up to 75% heat recovery). If the building includes self- generating power capability (via a PV array for example),the NV-HR system can even become carbon negative.


It is also possible to incorporate an LPHW coil within the NV-HR system. This provides additional heating beyond recirculation of the warmth extracted from the heat recovery process, addressing those colder days. It goes beyond that, eliminating the need for – and therefore the design impact, space allocation, installation costs and embodied carbon of – separate central heating emitters (radiators). And, if the heat source is a ground source heat pump, with addition of a plate heat exchanger it can also provide temperate cooling for just the cost of running a


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Attention to the design details, such as the choice of air distribution diffusers, can also give a positive contribution towards a low/zero carbon strategy, at very least optimisation of energy efficiency. Thermal swirl diffusers monitor the incoming air temperature. When it varies beyond a degree or two above or below the preset, the swirls automatically adjust their omni-rotational diffuser vanes, delivering warm air vertically and cooler air horizontally. This process ensures rapid initial warm up and avoidance of uncomfortable draughts. The change happens within seconds, maintaining the equilibrium without any major fluctuation between cool or warm inside. Thus it potentially has a huge impact on energy demand ‘spikes’ compared to alternatives that can take up to an hour to adjust. No external power source is needed. Pupils are not distracted by feeling too hot nor too cold.


Linear grilles or diffusers adjacent to expanses of glazing can help modulate solar gain and avoid risk of condensation, both of which impact the energy consumption of the internal space. There are, therefore, numerous options to help move towards greener ventilation strategies in our education estate. Today’s architects have the added advantage of computer technology. Software such as BIM and CFD (computational fluid dynamics) mean you have the power to test the theory before a single component is ordered, to make miniscule – or major – adjustments to improve the energy performance and make it as low carbon as possible given the other project constraints.


All we need is a little imagination, to venture beyond the accepted and conventional way of doing things.


Ian Rogers is sales director at Gilberts ADF MAY 2024


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