Schools and education facilities supplement Classroom ventilation
> be properly commissioned and work in tandem with be removed from the building fabric, further reducing
fi nely tuned control systems, enabling the contra fl ow the cooling load and running times.
“Energy
of the supply and extract air streams through a heat ‘Proper time scheduling, restricted temperature
recovery in
exchanger to achieve a high temperature-exchange settings and effi cient zone management are also areas
the ventilation
effi ciency, offsetting much of the additional energy where additional savings can be made – or lost.’
needed to drive a mechanical system. Paul Price, So, is the answer mechanical systems with clever
cycle is often
technical director at Gallant Air Conditioning, believes technologies used to recover the extra energy, or
overlooked” –
energy recovery in the ventilation cycle is often fully automated demand-led natural ventilation – or
Paul Price
overlooked. ‘No matter how effi cient the heating and a third way? Building services designers now have a
cooling system is, if heat energy is simply expelled range of options at their disposal and BSF budgets
from the building through ventilation extraction, the to spend. However, the jury is still out on whether
design is fundamentally fl awed. this will mean that future generations of school
‘Engineers can also design in night-time cooling children will be learning in better ventilated spaces. ●
for the summer months by using a bypass mode,’
explains Price. ‘Night-time cooling cycles allow heat to Download Building Bulletins from www.dcsf.gov.uk
Case study Community centre needs continuous ventilation
The £70m Hadley Learning Community (HLC), than 100 zones – all linked to a central control
above, completed in 2007, was the fi rst of its kind system. The system was developed to exploit
in the UK to bring together primary, secondary the high thermal mass created by the building’s
and special needs school facilities and additional structure to ventilate rooms naturally and maintain a
services for the wider community – including comfortable, fresh internal environment.
facilities for sport, arts, lifelong learning and a public The computer enables accurate interrogation
library. The 30,000 sq m building is a complex of the temperature and carbon dioxide levels.
design, combining single and two-storey spaces WindowMaster says it extracted data in March 2009
which radiate from a central open space hub in to show CO2 levels in two zones to ascertain the
a series of zones. HLC opens between 7am and effectiveness of its NV Advance system over time.
10pm during the week and opens at weekends and Data from a standard classroom and a science block
school holidays for community use. The natural were analysed throughout a typical week in term
ventilation system therefore has to be able to deal time. During peak usage, CO2 concentration levels
with continuous operation. reached around 1,900 parts per million (ppm) on
WindowMaster, the ventilation system supplier, one day and 1,300ppm on another. During the rest
says it used computational fl uid dynamics software of the week CO2 levels were maintained at around
to model and understand the effects of wind around 600ppm. The British Standard recommends that
individual buildings at the HLC. It used 3D computer the maximum CO2 concentration should not exceed
simulations of the building structure and its 5,000ppm during the teaching day.
surroundings, including trees and other buildings, A weather station monitors the external conditions
“Innovative
which affect wind fl ow. It also took into account around HLC, including wind direction and speed,
design of natural factors such as the building’s fabric, its construction, temperature and rain fall and changes in wind
ventilation
size, design and usage. pressure on the facades. This data is fed into the
Using this software, engineers split buildings computer control system where it is analysed along
systems for
into different internal zones and designed systems with readings taken from sensors fi tted internally.
urban schools that enabled building occupiers to create different Windows around the building are then precisely
has an
climates in separate areas. More than 600 motors controlled and positioned to keep air quality
were used for the windows, as well as temperature within rooms fresh and the temperature constant,
enemy: noise” –
sensors and manual override switches in more according to WindowMaster.
Richard Arnott
18 CIBSE Journal February 2010 www.cibsejournal.com
CIBSEfeb10_School_pp12-14,16,18_Ventilation.indd 18 25/1/10 15:41:42
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