Carshalton College ASD and Vocational Training Unit
Each of the 11 classrooms, spread over 3 floors, has 44 Velfac AOV (automatic opening vents) windows on the external facade, a damper to a ducted air handling system and under floor heating.
SE Controls’ solution was to provide a fully automated stand alone Natural Ventilation system that could be controlled by a Graphic User Interface (GUI) from any networked PC. A weather station was fitted to the external façade of the building and was connected to a Nat Vent programmable Controller that would take all of the data from the rain, wind and temperature sensors and pass these through the OS2 Type 21 Controllers placed in each classroom to interpret the data and open the AOVs accordingly. Each OS2 is connected to 4 TGCO 24 20 EasyDrive chain motors to automatically open the vents a predetermined distance, via a 0-10v signal, depending on the data received. For example, if the room temperature was warmer than the outside temperature the controllers would tell the vent to open until the room was at a comfortable level and then close. As these are opened the damper, also connected to the OS2, would open and extract air through the air handling system. As there was an inherent finger trap issue, because the vents were below 2.5m from the floor level, these motors have a restricted closing force on the chains so that if any appendage were to be trapped in a closing vent they would stop and reopen, also these motors have the added advantage of being fully programmable to suit any opening stroke up to 350mm and opening/closing speeds and force. A CO2 sensor has also been fitted in each room to also control the vents. Each teacher also has a key to a manual opener in each of the classrooms.
The idea of the GUI was to give the teachers simplistic control of the system so that pupils and themselves were comfortable, well ventilated and not distracted.
Natural Ventilation in Education Buildings
Architect: Tebbot and Wells
Specification: Natural ventilation system