6.0 Requirements for Sports
6.1 General
Expert judgment, calculations and modelling might
be necessary to assess the effects of daylighting. Flexibility in
design and implementation may also be required. The advice given in
CIBSE publications, such as the Energy Efficiency in Buildings book and
the 1999 version of Guide A does now take into consideration some
daylighting aspects.
The general lighting description by CIBSE suggests
that, for energy efficient lighting the following criteria should be
followed28 :
maximise natural daylight
avoid unnecessarily high illuminance
incorporate the most efficient luminaires, control
gear and lamps
include effective lighting controls.
The generic and specific guidance are however, not
complimentary. The CIBSE Code for Interior Lighting, published in 1994
and the CIBSE Lighting Guide: Sports LG4, published in 1990, are not
up-to-date regarding the use of daylighting in sports halls. The CIBSE
Code does mention daylighting in sports halls briefly, and recommends
that “only high level, north facing glazing be installed. In the
past, rooflights and deep well glazing have been installed but this can
cause maintenance problems.” This seems to indicate that the use
of clerestories at the top of a north facing wall is preferred, but
this would not produce an adequate or even daylit illumination.
If designs are to include daylighting it is
necessary to refer to procedures used in applying daylighting for
offices and other similar interiors. This is not wholly satisfactory,
as criteria to be met in an office differ significantly from those in a
sports hall. For example, computer screens have to be catered for in
offices, whereas in a sports hall, glare from ceiling lights (natural
or artificial) is a particular problem for badminton players. The sizes
of the spaces often differ significantly, with sports halls having high
ceilings of, typically, over 7 metres and offices with ceiling heights
of 3 metres or less. This affects both the artificial and natural
lighting scenarios and light distribution within these spaces.
CIBSE is not the only institution to have either
limited or restrictive advice regarding daylighting, particularly in
sports halls. The existing advice given in Sports Council documents is
unenthusiastic about natural lighting and traditional guidance tends to
follow the principles of designing for windowless halls. For example,
the table tennis advice booklet29 mentions
that “natural light is so difficult to control to give consistent
lighting levels that it should be excluded from the playing hall either
by the use of effective blinds or by design of ‘black box’
halls”. Few halls are designed exclusively for the use of table
tennis but meeting this requirement has evidently been one of the
factors which has driven traditional design.
It is not just table tennis where attitudes to
daylighting are unenthusiastic. The gymnastics advice leaflet from the
Sports Council30 says that “if you choose or need to have
natural lighting in the hall, consider the positions of windows
carefully. There is no need for gymnasts to have a view out; it will do
nothing but distract from the intense concentration required for this
sport”.
It can prove difficult to know quite how to design
a daylight scheme and adhere to the apparently strict rules of CIBSE
and the various sports bodies. Yet, if we wish to encourage energy
efficiency and creative use of internal space then a range of
techniques might be considered prior to the adoption of the
“black box” approach.
6.2 Preferred Lighting:- High v. Low Illuminance
Conflicts with artificial lighting tend to focus on
glare problems, especially when players are looking up to the ceiling,
as in badminton. Modern artificial lighting addresses this issue by
placing lighting to the sides of the playing area. At the same time,
this improved artificial lighting needs to be integrated with natural
lighting from rooflights, or windows in other locations, such as at the
tops of walls (clerestories), as shown in fig 6.2.2. It is this
integration that is the most difficult to achieve satisfactorily,
without creating problems of glare, overheating and uneven lighting,
for example, when the sun comes and goes from behind the clouds.
A new view on lighting of interior spaces has led
to a change in the way that illuminance levels and lighting design vary
significantly from existing advice. Past practice, and existing design
methods, have tended to specify the “low luminance”
lighting method. This is the basis of the CIBSE Lighting Guide LG3,
which is now regarded by some as unhelpful and detrimental to
furthering lighting design.31,32 This method
can be found in most offices and sports halls, where the lights are
mounted in or below the ceiling, shine downwards and provide a set
illuminance level on the working plane (usually at 0.8 m above floor
level for offices and at floor level for sports halls).
The main disadvantage with this is that the
ceilings remain in shadow, compared to the bright, downward pointing
light source; giving a gloomy appearance to a room. There are also
glare problems, due to the contrast between the bright light source and
the dark ceiling behind or next to it. Most luminaires have a distinct
cut-off of illumination outwith a certain lit area. This exaggerates
the above problems.
The latest thinking in lighting design is based
around the “high luminance” method, where light is
“thrown” around a space, both up and down and side to side.
This brings up the background light levels on all surfaces, giving a
bright and spacious feeling to the room. This reduces contrasts and
subsequent glare problems. It also links in well with daylighting,
provided that the two forms of lighting are controlled well and the
progression between natural and artificial lighting is gradual.
Artificial illuminance levels close to the windows
should actually be higher than those deeper in the room, as the main
problem with glare comes from high contrasts between the windows and
the surrounding walls or ceiling. If these surfaces are well lit by
artificial lights, the contrast, and therefore the glare, is reduced.
6.3 Optimising Natural Light
The interaction between daylighting and artificial
lighting is crucial if there are to be energy savings and satisfactory
standards of light levels, without glare. The natural light may be
optimised, in general cases, by following the advice shown in fig. 6.3.33
It is essential to achieve a balance between useful
daylight and unwanted solar gains. Increased daylight may result in
less use of electric lighting and hence reduced cooling loads. However,
increased solar gains during summer could outweigh the benefits.34
The best method of integrating daylighting with the
artificial lighting is to use switching systems that provide the
desired lighting conditions without being too obtrusive or complex.
Most people prefer to be able to over-ride the lighting controls at
some point, to feel that they have control over their environment.
However, should the lighting system sense that energy is being wasted
and the perceived conditions are inadequate or unsuitable, then it
should be capable of switching to an automatic state.
