Improved indoor environment and ventilation in schools. A case study in Vaxjo, Sweden.

During the last decade several surveys in Sweden have indicated that the indoor climate in existing schools is unsatisfactory, therefore a thorough project was carried out in Växjö). The indoor climate was investigated in three schools during 1989. Detailed measurements were made of ventilation (e.g. rates, air exchange efficiency), indoor air quality (e.g. CO2) and thermal comfort (e.g. air velocity). The main results were: high indoor temperatures, low air velocities and high concentration of CO2. Improvements were made in all three schools during 1990. One of the classrooms was rebuilt to have its own separate ventilation system with the possibility to use either ceiling diffusers or floor supply air terminal devices. After the improvements the measurements were repeated. The CO2 concentration and the air temperature were measured at different locations within the classroom, at different air flow rates and at different supply air temperatures. The air exchange efficiency was determined for different air flow rates and different air supply systems. The following recommendations were made for the schools in order to obtain - an optimum indoor air quality: air flow rate 8 l/s and person, supply air temperature 18 OC and four ceiling diffusers - a satisfactory thermal comfort: automatic exterior shading, circulation fan in the classroom, night cooling with outdoor air during fall and spring. The results of this project will be used to produce a manual "Indoor Climate in Schools".