book-2

8STRUCTURE AND LIGHTINTRODUCTIONFollowing the view that architectural space exists when it is experiencedby the senses, particularly sight, Van Meiss considers architecturaldesign to be ‘the art of placing and controlling light sources inspace’. 1 He understands light sources to include actual light sourcessuch as windows as well as illuminated objects like enclosing surfacesor other architectural elements that could include structural members.From this perspective, structure is potentially an important architecturalelement – both as a source of light, where light passes through itor illuminates it, and also as controller of how and where light enters aspace.When stone and masonry load-bearing wall construction dominatedprevious periods of architectural history, openings for light could beconsidered the absence of structure. Millet’s description of the relationshipbetween structure and light is particularly applicable to thatformer era. Focusing more on structure’s potential to control light thanfunction as a source of light itself, she writes: ‘Structure defines theplace where light enters. The structural module provides the rhythm oflight, no light. Where the structure is, there is no light. Between thestructural elements there is light.’ 2 However, since the introduction ofmetal skeletal structural forms during the nineteenth century, it is nolonger a case of either structure or light in architectural space – bothcan co-exist. Slender structural members have a minimal impact uponthe amount of light entering a space. Whereas the former prevalenceof masonry structure, in plan and elevation necessitated its penetrationin order to introduce light, in current architectural practice daylightrequirements frequently determine structural form and detailing. Contemporarystructure with its relative slenderness and small plan ‘footprint’can usually meet these demands.Depending upon its configuration, structure either inhibits or facilitatesthe ingress of light. In a building with perimeter structure that does notexclude natural light, structure relates to light in one of four modes –as a source of light where, for example, light passes through a roof trussto enter a space; to maximize light by minimizing the shadow effect of