Natural ventilative cooling during the day can be readily achieved by opening windows and rooflights. However, few schools make use of night ventilation. This method uses cool night air to reduce the temperature of a building’s thermal mass (walls, floors, furniture, etc.), so that on the following day less cooling energy is needed within the building.
Unwillingness to cool buildings at night likely stems from security issues and the possibility of inclement weather occurring when no one is there to close windows and skylights. One solution would be the installation of windows and skylights that can be partially opened to allow the entry of cool air, while preventing the entry of intruders or rain.
In countries where temperatures regularly reach 30°C or higher in the summer months, natural ventilative cooling may not be sufficient to keep classroom temperatures at a comfortable level.
In such cases, additional cooling devices such as ceiling fans and air-conditioning units are advisable.
However, field studies do show that people in naturally ventilated buildings accept higher temperatures (de Dear and Brager, 1998)¹. This is because the body adapts to its surroundings this phenomenon is referred to as adaptive thermal comfort. For this to be effective, it is vital that people can freely adapt their clothing and are able to open windows at will. In this way, thermal comfort can be achieved without air conditioning in even warmer climates, using only natural ventilation, solar shading and intelligent building design.
Whichever way it is achieved, thermal comfort in classrooms is essential to children’s well-being and, ultimately, to successful learning outcomes. Just like the porridge in the classic children’s tale of Goldilocks and the Three Bears, the temperature needs to be not too hot, and not too cold, but just right.
- de Dear and Brager (1998). Developing an Adaptive Model of Thermal Comfort and Preference. ASHRAE Transactions