Due to the increase in demand of energy efficient and durable buildings, design of building envelope sub-system is an important focus area in the building design process, especially in cold climate countries like Canada. The envelope is a major part of the building cost and is expected to last 30, 50, even 100 years.  The objective of this research is to model the building envelope design process and conceptualize a computer tool that could support the designers during the building envelop design process. It develops a concept for an integrated tool through a comprehensive study to understand the available design methods and their knowledge: by defining a generic model that could represent the design methods studied and their corresponding knowledge bases; subsequently, by defining a concept of the design tool with functions suiting the design process; and finally, translating some of the functions into a program to test, resulting in a prototype. (Abstract shortened by UMI.)