Indoor Air Quality in U.k. School Classrooms Ventilated by Natural Ventilation Windcatchers

The provision of good IAQ in schools is important both for the health of students and in maximising educational achievement. It is, however, common for school classrooms to be significantly under-ventilated and this can lead to high levels of CO 2 and other pollutants. Natural ventilation offers the potential to improve IAQ within schools whilst at the same time reducing running and maintenance costs. Accordingly, this article examines a natural ventilation strategy based on the use of a roof mounted split-duct Windcatcher ventilator. Here, 16 U.K. classrooms are studied and CO 2 , temperature, relative humidity and ventilation rates are measured for the summer and winter seasons. Results show that during the summer months the ventilator is capable of significantly improving ventilation rates as well as reducing CO 2 levels, especially when used in combination with open windows; however, in the winter months, the ventilator is seen not to open for a sufficient length of time and so CO 2 levels rise above those required in the standards. Thus, the ventilator is shown to have the potential to improve IAQ within school classrooms, but the operation of the ventilator should be carefully controlled in order to realise these benefits. It is common for ventilation rates in school classrooms to fall below the levels required by relevant standards. The data presented here demonstrates that by using a top-down natural ventilation Windcatcher as part of a well designed natural ventilation strategy, ventilation rates in school classrooms can be significantly improved.