The design and operation of buildings is a multi-criterion decision making process, there always being a trade-off of to be made between conflicting design goals (typically, capital cost, operating cost, and occupant satisfaction). Conventionally, the trade-off is ignored, since its identification requires the evaluation of multiple design and operating scenarios. The process is further complicated by the interaction between the building, its environmental control systems, and their control strategies.This seminar describes the application of Genetic Algorithm search methods in identifying the trade-off between conflicting design objectives. As well as indicating the sensitivity of one design objective to the other(s), the trade-off characteristic also indicates the inherent range of each objective for the building (this being useful for benchmarking building performance). The approach has the potential to be applied to the large-scale integrated design of all building systems, including thermal, lighting, and architectural systems. Results will be presented in the seminar for the thermal design of a cellular office.