I congratulate Arup on its design input into the John Madejski Academy as reported in the October issue of BSj, and hope that the outcome matches or exceeds the design intent.

I am very concerned, though, to read in the article that the design is based on a fresh air rate of 5 litres/s/p when the article itself notes ASHRAE guidelines of 6.2 litres/s/p, CIBSE recommendations of 10 litres/s/p and DfES BB101 requiring a capability of 8 litres/s/p.

I was also rather surprised to see the design concept being put forward as in some way revolutionary. While working at Whitby & Bird (now Ramboll Whitbybird) in the 1990s, I completed a design with architect Ellis Williams Partnership for an extension to Greycoats School in Westminster, a much more onerous inner-city site, with a natural ventilation scheme practically identical to that shown (except for the rather nice plastic cone), but based upon a more realistic 8 litres/s/p.

And finally, the CFD diagrams shown were somewhat alarming as the winter scenario gave an outdoor temperature of 16ºC and the summer scenario gave a outside temperature of 21ºC. Hardly a rigorous design condition in either case!

Source

Building Sustainable Design

Postscript

Peter Mills, principal, the MEP Consultancy