Natural-ventilation system cools Coventry school

Natural ventilation based on passive stack ventilation is providing energy-efficient comfort throughout a 3-storey school building with 70 classrooms in Coventry. Coventry City Council asked Galliford Try to replace the old and crumbling Caludon Castle School with a new school and community college on the same site as part of a PFI. The first of two phases is the main school, a crescent-shaped block costing £21 million. 24 ventilation terminals on the roof are the only outward sign of the Passivent natural ventilation system which was developed with architect AEDAS. Galliford Try commissioned De Montford University to carry out a computer modelling study to determine the effectiveness of the ventilation scheme and ensure it met the requirements of DfES Building Bulletin 87. This requires 8 l/s of fresh air per person and temperature in occupied teaching spaces not to be above 28°C for more than 80 h a year. This passive stack ventilation relies on a combination of wind and buoyancy forces from rising warm air. Warm air leaving the building through the roof terminals is replaced by air drawn in through windows that can be opened by occupants and through louvres in the ceiling at the back of the classrooms. Motorised louvres control airflow across the classrooms and prevent draughts and excess heat loss through the stacks in cold periods. The builders stacks are segregated to avoid cross-talk acoustic issues.

Related links:

• www.passivent.com