The appearance of buildings of all periods reflects the nature of the
windows, in some cases such as the mediaeval period, the shape and
location of the windows being functionally related to the role played by
daylighting, whilst in the renaissance period the location and form of
windows became more formalized, often being less well related to the
interior spaces they served... the elevation, the appearance of the
building seen from the outside, became of prime importance, a
consideration which lingers on today.
Windows have always led to innovation, and this can be seen in the
stained glass windows of the great mediaeval cathedrals, telling the
Christian story, where whole walls of glass were made possible by
structures such as the flying buttress.
Windows had to serve military needs in fortifed buildings, leading to
slit windows from which arrows could be fired; with splayed sides
having the desirable effect of reducing the contrast between the bright-
ness of the window and the interior wall surface, a device which has
continuing validity.
A further innovative means of daylighting was that developed for the
lighting of the Baroque churches of southern Germany, where ‘indirect’
daylight onto the ornate decorations and ornaments of the church is
gained from windows concealed from the direct view of the congrega-
tion. Indirect daylighting is equally valid today, as used by Basil Spence at
Coventry Cathedral, or by Jorn Utson at the Bagsvaerd Church in
Denmark^2.
Whilst the vertical windows set into the outside walls of buildings were
clearly of the first importance, and continue to be so today, it was the roof
lights allowing daylight into the central parts of buildings that had an
important influence on the plan form of the stately homes of the
seventeenth and eighteenth centuries. These took several forms, from
domes such as that at Keddleston Hall (1759) where light enters from the
top or Chiswick House (1725) where the dome is surrounded by
windows in the sides, in both cases the method of daylighting allowed
architects to have more flexibility to plan the central areas of their
buildings. It is of interest that this method of introducing daylight to the
centre of buildings has a resonance with the atria which we see in many
buildings today.
The modern movement in England in the 1930s used the new methods
of construction available, to allow an entirely new approach in residential
buildings, with whole walls of glass and wrap-around windows at
corners to express the freedom of the relationship between inside and
outside, a freedom which was ultimately expressed in the walls of glass
now possible in tall commercial structures.
Daylighting remained the primary means of lighting to all types of
building until the early twentieth century, when for various reasons, not
least the greater efficiency in the development of electric sources, the
primary role of daylighting was beginning to be questioned.
The growth of the workplace in the nineteenth century had seen
buildings requiring higher levels of light, and this was achieved by
planning long horizontal windows, where the daylight close to the
window wall would have been sufficient, but with the pressure to reduce
the floor to floor height for economies of structure, even this became
insufficient.
4 Daylighting: Natural Light in Architecture
(^2) Lighting Modern Buildings. Architectural Press.