Future-proofing of requirements has enabled a new school to employ state-of-the-art ventilation to achieve a BREEAM very good standard.


Manchester City Council engaged the North West Construction Hub as a procurement vehicle to select ISG Construction Ltd as building contractor for a new, £1.6m extension at Benchill Primary School.


Architect Stephenson Studio designed in natural ventilation for the modular two-storey, 900m2 timber frame building comprising 6 x classrooms, a nursery, kitchen, administration area and ‘break out’ area. Building services engineers Ameon and international construction services company ISG met the ventilation brief by using the new Mistrale Fusion, developed and manufactured by leading air movement specialist Gilberts (Blackpool) Ltd.


The Mistrale Fusion 128 units have been fitted into the bulkhead of each of the classrooms and the nursery, with bespoke double direction grilles to provide compliant airflow of 8l/p/s into the room required by current Department of Education Building Bulletin (BB101) and PBSP guidelines.


Installed through the façade, uniquely, Mistrale Fusion mixes internal and external air to ventilate the internal space and deliver optimum internal air control for less than £5.00/room/annum1. The unit focuses on natural ventilation, incorporating a mixing damper within to modulate airflow and allow the new, fresh air to mix with warm exhaust air, thus extracting its heat without the need for an exchanger. An integrated low energy fan energises to blend the internal air, ensuring an even distribution of airflow, with control over temperature and CO2 levels within, and maintenance of internal occupant comfort conditions.


Each unit also achieves relevant acoustic considerations: its operational ‘noise’ is less than 32dbA, and it has been engineered to absorb external noise to keep within the classroom criteria required by BB93.


Mistrale Fusion attains air leakage better than legislative requirements- 5m3/HR/m2, and a U value of 1W/m2/°C. As with all Gilberts’ ventilation solutions, it delivers efficient weather performance via its bespoke louvre system.


Explained a spokesperson for ISG, “Planning and aesthetics of the building meant we needed a ventilation solution that would function as a ‘stand-alone’ system in each classroom that would be simple to expand as/when additional learning space is added in the future.


“Gilberts’ Mistrale Fusion met that requirement, and could be discreetly installed in plasterboard bulkheads; Gilberts’ ability to tailor-make a deflection grille to meet the design and airflow requirements was also an influencing factor.”


Founded 50+ years ago, privately owned Gilberts is unique in having its own, on-site (85,000ft2) manufacturing facility, producing engineered solutions, with an in-house test centre. Technical expertise is supported with full in-house testing addressing air movement andcombining with computational fluid dynamics CFD).


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