A series of air filled cushions across the main roof structure on a new college building in Glasgow provides high levels of insulation whilst allowing considerable natural lighting through.

The managers of the John Wheatley College gave architects ABK and engineers Buro Happold the brief to design a Breeam excellent building for its new East End Campus complex.

The resulting building uses extensive natural ventilation and lighting and renewable energy sources to achieve what the architects claim is “an exemplar low carbon building and which sets new standards in energy efficiency and sustainable design.” The 6,000sqm building is on a brownfield site in the Hagill District in Glasgow.

The roof over the concourse is triangle in plan and is similar to the one used on the Eden Project in Cornwall. It comprises a triple skin of ethyl tetra fluoro ethylene (ETFE) foils, which is stretched across the roof supports, and air has been pumped into each of the pockets to make a double layer of air cushions. The resulting covering is as strong as glass, it is possible to walk on it, but is very lightweight. A piece of ETFE weighs less than 1% of a piece of glass with the same volume. It is also a better insulator than glass, and is much more resistant to the weathering effects of sunlight. According to David Cruse, the project director at ABK the ETFE covering costs about the same. Solar gain from the roof is reduced by printing black spots on to the lower surface. The roof provides a strong sense of location and identity for the building and it covers the area, which is shared social space for exhibitions and events that is open to the local community.

Mechanical ventilation has been avoided in all the spaces except the IT rooms, with the use of passive systems, which enable a through draught. Most of the external glazing can be opened and ventilation shafts have been put in at the back of all the rooms leading up to wind controlled exhaust chimneys.

The concrete structure provides thermal mass, which is exposed. The concrete cools down at night and can therefore cool down the classrooms during the day. “In many buildings there are suspended ceilings which stop the concrete playing a role in managing heat in the building. We have avoided the use of suspended ceilings in this building to gain the cooling effect,” explained Cruse.

The building is heated by a biomass boiler, which was considered suitable because of the college’s relatively steady heating requirements. Biomass systems do not respond to rapid fluctuations in energy demand. They also generally require more maintenance than gas-fired equivalents, but as the college specialises in technical subjects including construction and building services, there are trained staff available to make daily checks. The boiler uses wood pellets from forests in the Scottish Borders. The boiler is controlled by a building management system, which runs the boiler at the right temperature and duration to respond to demand.

Solar panels are mounted on the roof and are used for heating the water and photovoltaic panels mounted on a section of the ETFE roof which projects over the edge of the building, also provide shade.

The Glasgow city council has strict criteria about drainage on new developments in the East End of the city  because of bad flooding problems in recent years. There is a requirement that new buildings can retain a considerable amount of water runoff in the event of a major flood. The building includes two large underground tanks for these situations. Rainwater is reused for flushing the toilets and landscape watering.

The building was more expensive
because of the sustainability features, but the college identified additional grant aid to pay for it. Cruse is confident that the extra costs were worthwhile, not only in terms of achieving higher environmental performance but to create a quality building. “Sustainability features need to be integrated into the whole design, contributing to the quality of the architecture,” he said. “You must not let environmental issues take over,” he added.