Passivent just the job for new school

Passivent natural ventilation has been installed by MandE contractor Dunwoody in one of biggest educational natural ventilation projects.

The new Church of England voluntary aided Bishop Justus School has been completed at a cost of GBP25m, to accommodate the growing need for pupil places in the Bromley area, and combines a six-form secondary school with a 6th form college, providing a learning environment for up to 1,200 children.

Built on a greenfield site within the local Green Belt, the brief to architects Barron and Smith was to minimise the environmental impact of the almost 11,000m2 school, including incorporation of sustainable techniques.

As a result, Passivent natural ventilation has been installed by MandE contractor Dunwoody throughout the teaching spaces, main hall and sports hall, to provide efficient ventilation to DfES guidelines during the day, and free night cooling.

Passivent believes the project is one of the largest educational natural ventilation schemes completed to date in the UK, using approximately 100 wall ventilators and 27 roof terminals.

On the ground and first floor, 70 Passivent Aircool ventilators have been fitted into the masonry walls along one side of the school, drawing fresh air into the classrooms.

The 'used' air in the classrooms is ducted up riser stacks by convection and exhausted using venturi principles via 17 Passivent Airstract terminals on the roof.

To optimise the internal environment, boost fans have been included in the food technology rooms.

Faculty rooms and music practice rooms have acoustic Aircools to attentuate noise.

On the second floor, 21 Passivent Aircool ventilators above and below the windows work together to provide low level ventilation with high level outlets, giving a draught-free flow of fresh air into the rooms.

In the main hall, 4 Passivent Airscoop displacement ventilation units are supplemented in lower windspeed conditions by 6 Aircool inlets, with a further 4 Airscoops fitted in the sports hall.

The two music rooms each feature an acoustic Airscoop to maintain a well-ventilated environment whilst minimising noise.

The Passivent Aircools use just 1watt of electricity to modulate the louvres to minutely adjust the flow of air, taking into account the weather outside- the speed and direction of wind, rain, temperature, and the location of the units within the building facade.

The units are set to continue working after school hours, using a night cooling function, to dissipate daytime heat build-up using passive stack principles (whereby warm air rises) to exhaust the warm air up the risers and out of the roof-mounted Airstract terminals.

Passivent Airscoop ventilators use a roof mounted terminal divided diagonally into four chambers.

Wind from any direction is channelled down through the windward chambers into the building, which exhausts warm, "used" air out through the leeward chambers.

John Drewery, architect at Barron and Smith, commented, "The Diocese of Rochester in its brief had a concept of a school which was environmentally friendly".

"We designed the school to fulfil that, including natural ventilation, sedum roofs, timber cladding and a sustainable urban drainage scheme".

"It is DfES requirement to utilise natural ventilation strategies if possible".

Passivent is part of the Building Product Design Group and is the UK's leading designer and supplier of natural ventilation systems for both domestic and commercial applications.

The company is a founder member of the NatVent EC-EU-funded project co-ordinated by the Building Research establishment to develop practical natural ventilation solutions for the commercial sector, and has also contributed to the BISRIA Guide BG2/2005 Wind Driven Natural Ventilation Systems, as well as being a member of the DfES steering committee on natural ventilation guidance for schools, Building Bulletin 101.

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