INNOVATIVE DAYLIGHTING SYSTEMS
In 1998 Paul Littlefair of the BRE wrote a seminal paper on this subject,
listing as its aims: to improve the distribution of daylight in a space and to
control direct sunlight.
Of the various methods none can be said to have achieved a universal
application, but each has a specific use and is worthy of mention.
Mirrors. There are many ways in which the interaction of light or
sunlight with a mirrored surface can be used for reflection. From the use
of a large hand-held mirror to throw light into the dark recesses of a
renaissance church for the delight of visitors, to the fixed mirrored
louvres which may be related to vertical windows, installed to direct light
upwards to a ceiling; alternatively there are those which, when related to
glazed openings in a roof, can project light downwards to the interior
(see Case Study of the Central United Methodist Church in Wisconsin pp.
142–143). These tend to be specialist solutions requiring the mirror to be
controlled by a motorized tracking system or heliostat... not for general
application.
Prismatic glazing. The principle is to use methods of refraction of light,
rather than reflection. Whilst this method can be applied to vertical
windows, they are perhaps more successful when associated with
systems of rooflight, a good example being Richard Rogers’ redevelop-
ment of Billingsgate fish market to a modern computer centre (see
Lighting Historic Buildings, p. 64) where sunlight is refracted away from
the occupants to eliminate glare, whilst allowing daylight to the space
below. As these have only a limited application they are expensive.
Light shelves. It is possible by means of comparatively inexpensive
building construction, to provide light shelves. These have already been
mentioned in terms of solar shading, but they are useful also to provide a
view window below the light shelf, with the light above reflected to the
ceiling to redistribute daylight further into the room. It must be
recognized that light shelves do not increase the daylight factors in a
room, but they alter the distribution, assisting in getting light further
towards the back of the room so that uniformity is improved. Light
shelves are relatively cheap to install, and are less subject to damage than
those used externally, but do require cleaning on a regular basis.
Windows 33Section illustrating the passage of light pipes
through a roof to provide daylight to a top
floor roomCourtesy of Monodraught Ltd