• a minimum of 3 l/s per person (litres per second per person), and
• a minimum daily average of 5 l/s per person, and
• the capability of achieving a minimum of 8 l/s per person at any occupied time. Additional ventilators could be used to provide this extra ventilation e.g. supplementing windows with the addition of louvres or stacks. This ventilation may not be required at all times of occupancy, but it should be achievable under the control of the occupant. When fresh air is supplied at a rate of 8 l/s per person, the carbon dioxide concentration will generally remain below 1000 ppm.
These flow rates should be based on the maximum number of occupants likely to occupy the space, and should be achieved under the design conditions indicated in Section 6.
The Department for Education and Skills has provided the ClassVent calculator to be used with Building Bulletin 101 that enables a designer to rapidly calculate areas for airflows into and out of a classroom. Designs using the ClassVent calculator (see Section 6) could be deemed to satisfy the guidance given in this section. Other design tools can also be used, but calculations for these designs would need to be submitted for building control approval.