With increasing urbanization today, the negative impact it has on its surroundings is prevalent in many cities and urban areas. Coupled with the need to create and develop sustainable urban developments, it is essential to understand how much the environment as well as its surrounding morphology affects the built environment. Greater emphasis should therefore be placed on urban planning which takes into consideration the surrounding environment and any accompanying effects it might have on the built environment. The integration of design tools with microclimate assessment tools therefore attest to be one with a promising future. This paper presents a methodology for evaluating the building performance of offices in Singapore whilst taking into account its surrounding morphology using GIS as a platform for integration with an urban climatic assessment tool. Hourly weather data which accounts for the urban morphology (input to the model) is obtained by morphing maximum, minimum and average temperature (the output of air prediction model STEVE) into a typical 24h profile. Good agreement was found between predicted dry-bulb temperatures and measured data. A total of two indicators of envelope performance were used and they are (1) increase in conduction (wall, window and roof) heat gain and (2) solar heat gain through glazing taking into account shading by surrounding buildings and morphology. The model was shown to have good agreement with building energy simulation programme IES-VE.