A methodology for integrated daylighting and thermal analysis of buildings

During the conceptual design stage of a building, the design team often has to make critical decisions with significant impact on energy performance and indoor comfort conditions. The design and selection of fenestration systems and their control plays a key role in determining building performance, especially for perimeter spaces of commercial buildings. The domains of heating, cooling and lighting are closely related. An integrated thermal and daylighting approach is required for investigating the interactions between the different building systems. Advanced building simulation software can be used to evaluate overall building performance for specific fenestration schemes. However, these tools cannot provide information on how to select near-optimal design solutions from a large set of alternatives, since they require detailed input data which are not yet available at the early design stage. Therefore the selection of final design solutions concerning fenestration often involves many subjective factors. In this Thesis, a general and systematic simulation-based methodology for integrated daylighting and thermal analysis of facades and perimeter spaces of commercial buildings during the early design stage is presented. Using a systems integration approach, major dynamic links between thermal and daylighting performance are identified and used as design variables in a coupled thermal and daylighting simulation program. Integrated performance-based indices, generated from the continuous interaction between daylighting and thermal simulation, are calculated as a function of key linking parameters for investigating the balance between daylighting benefits and energy performance. The variation of these measures allows extraction of critical information for selection of window-to-wall ratio, shading device properties and control plus electric lighting control strategies. Maximization of daylight utilization, reduction in peak loads and energy demand for heating, cooling and lighting are used as criteria. The methodology is general and can be applied to any type of façade, location, orientation, glazing type and shading options. Results presented for perimeter offices in Montreal provide guidelines for selecting window-to-wall ratio for unobstructed façades, as well as recommendations for choosing shading device properties and control in conjunction with electric lighting operation