Schools and education facilities supplement Classroom ventilation
Mechanical ventilation is at
> traditionally designed buildings to achieve modern requirements of their pupils – all 3.3 million of them –
the heart of debates about
fresh air levels thanks to the effect of cross and stack through natural ventilation alone? Not many, according
how to achieve the best
ventilation. However, as the main control technique is to a number of leading design engineers.
environment in schools.
opening or closing windows, pupils and teachers will School designers have a different attitude to windows
regularly complain of draughts, noise and stuffi ness, these days too. They are now seen as a security risk, so
often simultaneously. In many cases, such an inexact are only openable to a degree – usually to a maximum
control mechanism cannot be relied on to adequately of 25cm. They are also a potential source of noise and/
reduce CO2 concentrations. or air pollution, all of which makes it tricky to design
The schools being significantly refurbished or an effective natural ventilation system. Yet, can the
built from scratch under the Building Schools for school afford the running costs and carbon penalty of
the Future (BSF) programme, which is due to spend a mechanical alternative?
£9.3bn between 2008 and 2011, are being designed to
be far more air tight than their predecessors to meet Research
modern energy efficiency standards. This makes Academic research seems to show that many current
controllable ventilation critical. Increased use of IT strategies, even in newly built BSF schools, are failing
has also given designers the additional challenge of to reach the required standards. Derek Clements-
combating overheating, and external ambient noise is Croome, of Reading University, has worked with fellow
an increasing problem on many sites too. academics in this area for many years. His studies
Despite all this, it is noticeable that many of the case show that the ‘complex interaction between thermal
histories championed by Partnership for Schools (PfS) comfort, ventilation and acoustics when providing
– the body charged with delivering the new generation good classroom design presents considerable problems
“Complex of BSF school buildings – make a virtue of natural for designers’, he says.
interaction
ventilation. Bideford College in Devon, which was ‘Overall, it would seem that the basic requirement
crowned Most Sustainable School in the 2008 BSF of 1,500ppm of carbon dioxide is achieved as a
between
Awards, emphasised that natural ventilation was a key consequence of window areas being just suffi cient to
services presents aspect of its bid for BREEAM Excellent rating. The PfS provide the required level of fresh air with low and
considerable
says that it is ‘committed to reducing carbon emissions intermittent occupancies,’ says Clements-Croome,
from schools, with all buildings making the most of who is also chairman of the CIBSE Natural Ventilation
problems for
sustainable features to help protect the environment Group. ‘And, in any case, we would argue that the level
designers” – and reduce overheads’. should be below 1,000ppm.
Derek Clements-
However, how many of the 3,500 state secondary ‘To meet the higher supply rate of 8l/s per person the
schools in England, which are due to be rebuilt window installations frequently provide an inadequate
Croome
or remodelled by the programme, can meet the openable area. Furthermore, we concluded that the >
14 CIBSE Journal February 2010 www.cibsejournal.com
CIBSEfeb10_School_pp12-14,16,18_Ventilation.indd 14 25/1/10 15:39:49
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