Daylight Linking
Daylight alone does not deliver energy
efficiency. Daylit sports halls are only energy efficient if
the artificial lighting can respond to the levels of daylight.
Although there will be amenity benefits, energy and running
cost
Shading Types
An early example of a daylit sports hall
can be seen on the left. The mercury halide lighting and
rooflights are hidden behind a large sailcloth canopy (velarium
). The result is successful in terms of occupant satisfaction,
but the diffusion cuts down on both the efficiency of the
natural and the artificial lighting.
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The Fabric of a Sports Hall
The materials from which a sports hall is
constructed play an important part in its capital cost, running
costs, acoustics, appearance and thermal response. Lightweight
constructions, such as timber; steel frame and cladding,
require less warm-up time, but are more prone to overheating in
the summer. Heavyweight buildings use blockwork or monolithic
construction and provide a more stable thermal response.
Windows themselves create particular problems, especially in
terms of thermal performance and acoustics. For many halls, it
is the roof that provides the acoustic tuning opportunity, and
for daylit halls, this is where windows are often located.
Consideration for both, and the requirement to provide an
unbroken, light coloured appearance mean that the ceiling is
often one of the most critical areas of design, and frequently
the one that suffers due to poor attention to detail.
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Surface finishes can be a source of
problems. Reflections from floors and backboards are common.
Poor selection of window surrounds contributes to problems of
glare. Even standard blockwork finishes can be problematic with
light reflecting off edges giving rise to unwelcome patterns of
light which can disrupt play.
Ventilation
Window design should be an intrinsic part
of the ventilation strategy and the building manageability will
be much reduced if this is not planned at the outset.
In general sports halls do not have to
account for high heat loads or require humidity control and
well designed natural ventilation will often be adequate.
Trickle vents can provide background ventilation. Openable
windows at high level allow excess warm air to be released and
cooler air to be drawn in at lower level.
For the majority of sports facilities
mechanical vent should only be required when the hall is in
continual use or is occupied by a large number of people. It
should be variable volume and effectively controlled.
Interlocking window openings, occupancy and ventilation will
improve efficiency
However conflicts arise with some sports
because of the internal air movement which can be generated by
natural ventilation and for this reason some kind of mechanical
ventilation is often preferred. Dynamic Insulation has been
shown to have benefits in delivering pre-heated
ventilation air at low velocity to a space in combination
with natural ventilation in summer conditions - but air
movement may be unacceptable
Situations may also arise where high level
play requires that daylight is excluded and windows closed to
keep air movement to a minimum. These issues need to be
resolved at the outset and either fully designed solutions
sought or clients and funders need to be made aware of the
design limits. Contingency sums or charges established as part
of any cost model may be identified to provide for occasional
temporary shading for example.
LT Method
The Lighting and Thermal (LT) Method
provides a means of estimating, during the initial design
stages, the optimum amount of glazing needed. Consideration of
efficiency gains from daylighting and thermal losses due to
glazing generates an optimum for a particular set of criteria.
Designed mainly for office and
institutional buildings, it can be applied to sports halls as
general guidance. The principal difference encountered when
using LT for sports halls is that all solar gain should be
excluded from a hall. Therefore, whilst the LT method
indicates the optimum proportion of glazing to wall area is 30%
for a south facing aspect, this is inappropriate for sports
halls. The method is more appropriate for designing the
ancillary spaces of sports facilities but is a useful guide.
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