Page 62 - Studio International - May June 1975

Tate Gallery extension lighting

Daylighting and electric lighting systems for the

Tate Gallery extension
Client — Department of the Environment in association with the Tate Gallery. Architects — Llewelyn Davies Weeks
Forestier-Walker & Bor in association with the Property Services Agency of the Department of the Environment.

Although sun screens have been known in illumination will be pre-set to two ranges, fluorescent sources and will be housed in
one form or another since men crept out between 75-15o lux or between 150-300 the centre of each bay in the base of a
of their caves, the most common form in lux. Within each range, the electronic truncated pyramid. This lighting will
modem architecture has been for screens controls will adjust the louvres to achieve phase in gradually as daylight levels fall.
to keep the sun from the vertical faces of light levels at the mid-point within these The task lighting will be from tungsten
buildings (eg Le Corbusier's 'brise limits, ie 112.5 and 225 lux respectively, filament lamps mounted on two tracks
soleil'). In only fairly recent times has the and unless the light changes to a level and recessed into the edge of the central
principle of sun screens over roofs been above or below the limits, no adjustment pyramid so as to be less obtrusive when
adopted in galleries. There are two will take place. not in use. The use of tracks will provide
notable antecedents to the Tate Gallery, The controls are designed to deal with gallery staff with the maximum scope for
ie the Art Centre at Le Havre, and the excessive variation in illumination levels selecting the type and location of fittings
van Gogh Museum, Amsterdam. from natural sources between winter and to best suit particular displays. One of the
However, both these buildings have fixed summer, but must avoid 'hunting' and two tracks will be used for the task
screens or louvres, whereas the technology preserve minor variations in light levels lighting required when daylight is
has advanced in this country as will be which are characteristic of natural light. inadequate; the other will be available for
seen in the following description. Beyond the predetermined limits controls special lighting where this is required
A primary objective of the design of the will either open or close the louvres. If even when the gallery is otherwise
new extension to the Tate, now under opening the louvres does not provide naturally illuminated.
construction, is that works of art should sufficient illumination the artificial The lighting design was originally
be seen in natural daylight whenever and lighting will switch on automatically. developed using a scale model of a group
wherever possible. In proposing Manual over-rides will be provided to of three gallery bays and the artificial
solutions to this problem the designers enable gallery staff to adjust the lighting lighting design has been further studied
have felt it essential that, while providing to levels outside the two basic limits. For in more detail in a full-size mock-up of a
adequate controls to protect works of art example, the louvres can be closed new gallery bay mounted within the
from damage caused by light, it should completely to produce near blackout existing Tate. The control system for
remain obvious that natural light is the conditions, or alternatively, opened to natural lighting and for the interaction
main source of illumination and that one suit an installation where conservation of between natural and artificial light will be
of the essential characteristics of natural the objects displayed is less critical. The evaluated in one bay of a new extension,
light, its variation, should not be lost opening of the louvres under these which is being completed in advance for
through over sophistication of control. circumstances will be limited so as to this purpose. •
The new extension provides a large maintain the proper temperature and
space free from supporting columns humidity levels. As an additional aid to
divisible in to 21 separate bays, each conservation, the controls will ensure
approximately 3o ft square. The roof of that at all times when the gallery is closed
each bay is designed as a separate unit to the public the louvres will be
containing independent air-conditioning, completely shut. The artificial lighting
daylighting and artificial lighting. Any will be provided by a combination of two
number of bays may be combined to suit components 'building lighting,'
layouts of varying size and character. primarily background lighting and 'task
Each square bay is covered by a pyramid lighting' which will illuminate the works
of clear glazing incorporating an ultra- of art. The building lighting will be from
violet filter to exclude radiation at the
wavelengths most damaging to paintings.
Below the glazed roof the surfaces
enclosing the structure and service
trunking, together with the sides of a
central truncated pyramid are used to
give an even distribution of light on the
wall surfaces. The pyramidal forms of the
roof combined with the square planning
grid ensure equally good lighting on all
four sides of each gallery bay.
Above each glass pyramid a double
layer of aluminium louvres will be used
both to keep natural light within the
limits required for conservation and to
reduce the amount of solar heat reaching
the gallery to manageable levels so that
temperature and humidity limits can be
maintained. One layer of the external
louvres will be used primarily to exclude
excessive heat gain by adjusting the angle
of the louvres on a seasonal basis as solar
radiation varies throughout the year. The
controls of the other layer of louvres will
be activated by a photo-electric cell in
each bay, to maintain the lighting in each
bay at the level appropriate to any
particular paintings. The levels of
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