Schools and education facilities supplement Case study
F
ordham
Max
The cross-ventilation scheme uses acoustically-attenuated openings to allow air to pass from classrooms into the central circulation space.
The light shafts cut through each fl oorplate in the circulation space, allows warm air from the classrooms to rise through the building and
exit through high-level ventilation openings at the top of the circulation area. On the third fl oor, classrooms are cross-ventilated directly to
outside through an opening in the roof plate.
> Education publication states minimum good practice openings at the top – provides rapid daytime and
should be considered to be a fi ve per cent average in any secure night-time ventilation.
teaching space, with a minimum point daylight factor ‘The few spaces that are mechanically ventilated
of two per cent in all of the room, up to 0.5m from have their own local ventilation systems, so the air
the walls. Simple building user guides are provided comes in generally from just outside,’ says Bentham.
to enable occupants to operate the blinds to control ‘So we are not moving large amounts of air around the
natural light. building over long distances – which reduces energy
Designing effective natural ventilation to cool the consumption.’
building was complicated by the fact that the site is In terms of temperature control, the City Academy
fl anked by a busy main road producing very high levels is made of concrete, which provides thermal mass.
of ambient noise. The designers did not want to resort In summer, the concrete absorbs heat by day and is
to energy-intensive mechanical ventilation and cooling, cooled at night by passive ventilation. The thermal
so a combination of a double façade and attenuated mass stores ‘coolth’ from the night to regulate daytime
ventilation openings were used. temperatures.
A glass screen ‘sits off’ the building by around a metre Other features to limit energy consumption include
and this refl ects some of the noise but also allows air demand-led mechanical ventilation linked to CO2 and
to move in behind it, says Bentham. Behind that there presence monitors, push-button timed-fl ow showers
is a louvre window which features acoustic-absorbent and taps to minimise water use, high-efficiency
foam that ‘deadens’ any noise. Behind this louvre, the fl uorescent lighting, and extensive sub-metering to
windows into the classrooms open inwards. allow energy-use monitoring.
“In schools But crucially, to maintain the through airflow, Says Bentham: ‘When we start off on a project one
there is an
the classroom windows on the corridor side have of the fi rst things we do is look at other buildings of
acoustically-attenuated louvres to prevent noise mixing similar type and see where they use their energy, and
equal energy
either way. in schools there is an equal split between heating,
split between The target was to reduce ‘break-in’ from outside lighting and computer use.’ All in all, the greatest
heating, lighting
noise by around 25 decibels. The atrium means that energy savings are achieved through effective passive
a cross-ventilation strategy – where air passes from design, with the building services, controls and on-site
and computer
classrooms into the central space and buoyancy drives energy providing further reductions in energy use at
use” the warm air up and out through large ventilation additional cost. >
6 CIBSE Journal February 2010
www.cibsejournal.com
CIBSEfeb10_School_pp4-6,8_Academy.indd 6 25/1/10 15:38:19
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