Optimising the design of building envelopes for thermal performance

Computer models for the simulation of the thermal performance of buildings have been in existence for many decades. Although these programs save a great deal of time and effort in computational terms they still rely on designers intuition and experience to achieve optimum solutions for a design problem. This paper presents a computer model which, not only simulates the thermal performance of the building taking into account design variables related to the building's envelope and fabric, but also applies numerical optimization techniques to automatically determine the optimum design variables, which achieve the best thermal comfort conditions. The main optimization program is supported by a graphical model for the design of window shading devices, which uses the numerical coefficients that define the window shading to model shading devices taking into account seasonal variations in solar angles and solar gains. The rationale and methodology used to develop the models is outlined and the resulting programs an described with examples of outputs. Finally, it is concluded that the models offer a valuable decision support system for designers at an early design state for the optimization of the passive thermal performance achieving optimum thermal comfort and savings in heating and cooling energy. (C) 2000 Elsevier Science B.V. All rights reserved.