About the Calculation Method “VDI 6040 Schools (09-2015)”

Explains the concept of determining required air volumes for rooms in non-residential buildings based on the calculation method VDI 6040 Schools (09-2015).

The calculation method VDI 6040 Schools (09-2015) is used to determine the required air volumes in classrooms and common rooms in general and vocational schools where pupils are regularly taught or supervised.

The underlying guideline VDI 6040 describes the requirements for indoor conditions with regard to the operative temperature, humidity and material composition of the indoor air. The required outdoor air volume flow results from verification of a time-weighted average CO2 concentration of 1000 ppm in accordance with Sheet 1 of VDI 6040.

Since the CO₂ concentration of 1000 ppm in the Room must not be exceeded at any time during the school day, the individual teaching units and the breaks in between are considered. This is done by defining the teaching units and breaks as individual time intervals in usage profiles. These usage profiles are then assigned to the rooms.

For the volume flow determination of the required outdoor air volume flow rates of the individual rooms, the type of room occupancy and the grade level taught in the room must be determined. Based on these configurations, the hourly person-related CO₂ volume flow rate is set automatically. Furthermore, the CO₂ concentrations in the outdoor air and in the room air are needed at the starting point of the school day. With these entries and the number of people and duration of the individual intervals defined in the usage profiles, the required outdoor air volume flow rates of the rooms are calculated. This is done by estimating a starting volume flow rate when considering the first interval, with which the CO₂ concentration at the end of the interval is calculated. In this process, the program checks whether the CO2 limit value of 1000 ppm is exceeded. If the limit value is exceeded, the start volume flow rate is increased accordingly until the limit value is no longer exceeded. This interval-internal process is carried out iteratively for all intervals, whereby the final CO2 concentration of the previous interval is used as the initial CO2 concentration. The time-weighted average CO2 concentration determined from the individual final concentrations and required for the verification as well as the required result volume flow rate are output in the results at room level.