Robust, rather than revolutionary

The design was not intended to be presented as something revolutionary - we believe it to be a relatively simple, cost-effective and robust solution to the latest requirements of BB93 and BB101 and, as such, worth sharing with a wider audience given the large number of schools being designed.

The reference to 5l/s/p is the minimum ventilation rate prediction under less than optimum wind conditions with the windows shut, and, of course, windows can be opened at any time to increase ventilation rates well above 8l/p/s. That is in compliance with BB101, which specifies a minimum rate of 3l/p/s (we could have an interesting debate as to whether that rate should be revised - personally, I think it should be increased). Also, in any naturally ventilated design it is impossible to accurately control ventilation rates all the time and they will fluctuate with outside conditions, which complicates setting minimum rates.

Peter will be relieved to know that the CFD study was not used to size the heating systems; it was intended to investigate the air distribution within the classroom on "typical" days adn to look at the CO2 concentrations.