Commercial Building Facade Design: Improving the Consistency of Early Design Tool Predictions and Detailed Design Tool Calculations

Abstract

The focus of this research is the concept of the 'Performance Sketch' tool. This is to use detailed simulation software to calculate (plausible) energy performance of designs quickly. Analogous to the Architectural Sketch the Performance Sketch uses high quality tools (detailed simulation) to create an accurate, but simple representation of the essential properties of a building, as opposed to a detailed representation. The aim of this research is to assess the consistency between the predictions produced by performance sketch design tools and the calculations produced by detailed design tools. The Lawrence Berkeley National Laboratory’s (LBNL) computer software COMFEN (COMmercial FENestration) is a performance sketch tool. It makes the power of the complex detailed design simulation package EnergyPlus available in the very early stages of the design process. It uses a single zone, single external façade EnergyPlus model to explore the costs and benefits of alternate façade designs. The hypothesis tested is that the COMFEN (single-zone) energy performance calculation method is plausible for early design analyses. It evaluates the performance sketch approach from three different points of view: first, COMFEN was introduced to various practitioners in the building industry to gather use-case feedback on the performance sketch approach. A list of specifications for performance sketch design tools was developed based on these use-cases. Second, it examines whether the optimum façade identified by COMFEN creates the optimum performance complex building when this optimum façade is incorporated into detailed building models. Finally, refinements of the nature of the performance sketch based on this use-case feedback were tested in EnergyPlus. The thesis concludes by drawing together these three threads into an outline of a practitioner-based definition of an ideal performance sketch which has been tested in practical application.