The heat transfer performance of fenestration products is routinely determined using computer simulations combined with physical testing. Initial efforts to develop simulation and test procedures for the fenestration products in the 1980’s focused on simple planar windows since they are the dominant share of the market. However, once these procedures were developed (with resulting ISO standards and national rating and labeling requirements), manufacturers of more physically complex fenestration products (skylights, green house windows, tubular skylights) demanded procedures for simulating and testing their products. Dr Curcija has performed much of the R&D effort needed to evaluate the energy-related performance of these thermally and optically complex glazings over the past fifteen years. In this talk Dr. Curcija focuses more specifically on the research work that he has performed to develop testing and modeling procedures for skylights and projecting products (such as greenhouse windows). For both these product classes, 3-D computational fluid dynamics and heat transfer simulations were carried out. These results, along with detailed research level experimental data were used to develop sets of heat transfer correlations that are now being used by the window industry. Dr. Curcija will explain why CFD modeling is too involved for routine use by industry for these purposes and why physical testing is too expensive. The overall methods developed here are now being used by Dr. Curcija and others to develop procedures for additional classes of products, including popular retrofit products such as insulating shades and other solar control devices. Dr. Curcija is president of DesignBuilder Software USA, consulting company in Millers Falls, Massachusetts, dedicated to the development of models and software tools for building energy assessment. The company grew out of his consulting business while he was working as a senior research fellow at University of Massachusetts’ Center for Energy Efficiency and Renewable Energy. He is actively involved with ISO and NFRC standard development and has provided major contribution to the fenestration standards in simulation and testing. He has been a consultant on the development of LBNL’s THERM and WINDOW programs over the past 15 years, as the developer of thermal simulation engine for both programs. His company has developed several major software products, including a new commercial fenestration certification information system for NFRC as well as building energy simulation programs based on EnergyPlus. He is working with number of private companies on research and development of new products, where much of the work is proprietary and confidential.