With the increasing capabilities of computer modeling and simulation technology, the analysis of options for maximizing gains in energy efficiency for buildings can be realized more efficiently and cost effectively. Conducting building performance simulations allows for the analysis of the environmental impacts of buildings and the economic vitality of green building techniques. Commercial buildings consume nearly one-fifth of all the energy used in the United States, costing more than $200 billion each year. The building envelope plays a key role in determining how much energy is required for the operation of a building. Individual thermal and solar properties of glazing and shading systems only provide information based on static evaluations, but it is very important to assess the efficiency of these systems as a whole assembly under site-specific conditions. This paper presents a case study that was conducted using computer simulation tools to evaluate the environmental and economic impacts of using different types of glazing-sunshade systems on the overall performance of an office building in Florida. The case study results show how early stage building performance studies using computer simulation tools help practitioners in achieving the goals of reduced energy consumption and increased indoor comfort in an economical manner. (C) 2016 American Society of Civil Engineers.