Determination of office building shapes for the optimization of thermal conditioning and daylighting.

Abstract

By the 1950s, office buildings in the United States had become increasingly dependent on mechanical and lighting systems for environmental control. These systems provided comfort conditions in buildings that are strongly influenced by external and internal factors. Large heating and cooling loads, and large power requirements became common. The environmental control systems were, in general, technically successful, but their application caused large increases in energy consumption. Until the energy crisis of the 1970s, this consequence was a minor concern. More recently, rising energy costs, especially for electricity, have forced designers to rediscover energy-conscious design that passively utilizes building form as an element of environmental control for energy conservation. Significant reductions in consumption are possible when the interrelationships of climate, building geometry and envelope, and internal loads are well understood. A building's energy use is considerably influenced by early decisions on such design issues as site development and building shape, which can rarely be reconsidered close to or at the end of the design process. A building type with rather large energy consumption is office buildings. This study is concerned with decision techniques resulting in optimum energy use in office buildings. Its main concern is linking of daylighting, artificial lighting, and thermal analyses. The prime aim of this research is the development of a computer model which provides quantitative information on resolving the optimization problem between cooling, heating, and lighting energy usages. The model assists designers in determining overall office building aspect ratios, perimeter zone depths, and interior zone size and orientation of parallelepiped open plan office buildings at early stages of the design process. This study produces via computer simulation the balance point locations of perimeter zones; that is, the depth of space from facades toward the inside of the building at which external and internal factors result in the lowest overall energy cost depending on facade orientation, envelope design, indoor thermal and luminous conditions, and climate. Such distances from the facades, together with the energy costs, can serve as information for decisions toward optimum building shapes.