Through a window, brightly : modulating daylight and solar radiation in commercial and institutional buildings through the use of architectural elements

Abstract

Natural lighting serves several important functions in buildings. The visual power of a shaft of sunlight penetrating a dark space or the visual beauty of a stained window has long been recognized by architects and designers. The primary focus of this study is a more pragmatic one. Besides strong concern for the qualitative aspects of daylight design, methods of daylight and solar radiation modulation for commercial structures are explored and evaluated to offset electric lighting load or heat load requirements. An investigation into the energy use patterns of these building types - offices, schools, hospitals, warehouses and other "commercial" structures lead to the conclusion, that artificial lighting represents the most significant portion of total electrical energy consumption. This study considers daylight and solar design in several ways: First, it documents daylight and solar radiation fundamentals and their visual and thermal impact on human comfort. It reviews a series of traditional design tools and architectural elements to modulate and control daylight and solar radiation. Second, it proposes and evaluates an innovative daylight introduction system - a particular "lightshelf" configuration integrated as an architectural element - with careful consideration of the following criteria: - acceptance of the full range of seasonal sun altitude angles through a curved configuration of the reflecting lightshelf-surface to redirect incident radiation onto the same "reference-range" of the interior ceiling without and adjustments - modulation of daylight introduction and radiation diffusion for solar storage in distributed mass - penetration of daylight into a space beyond traditional limits of 15 to 20 feet for daylight utilization - design of the light introducing "component" as an architectural element and its integration into a modular window wall consisting of prefabricated lightweight concrete wall elements - evaluation of qualitative and quantitative performance of proposed system· - illumination and solar heat gain tradeoffs - integration of daylight design with dynamic artificial lighting system Third, analytical and experimental methods for daylight design are explored and an entensive daylight model experiment is executed to enable the qualitative and quantitative assessment of the proposed system. Finally, a number of case studies with innovative daylight introduction methods applied in praxis, are documented.