Building has significant impacts on the environment and natural resources. The emerging world energy and environment challenges demand a substantial revolution of building design philosophies. strategies, technologies, and construction methods. Vernacular architectures, built by people whose design decisions are influenced by traditions in their culture, have been gleaned through a long period of trial and error and the ingenuity of local builders who possess specific knowledge about their place on the planet. and thus are valuable in promoting climate-specific passive building technologies to modern buildings. This study introduced an approach to categorizing distinct vernacular regions and evaluating energy performance of ancient vernacular homes as well as identifying optimal constructions using vernacular building techniques. The research conducted an extensive Computer energy modeling for a number of representative ancient vernacular architectural characteristics observed for different climatic regions. The vernacular test subjects were compared against those established according to the International Energy Conservation Code and those generated by the optimization software. The simulation results of the energy models suggest that considering traditions seen in ancient vernacular architecture as an approach to improving building energy performance is a worthwhile endeavor and a scientific guidance can help enhance the performance. The study indicates that, although many vernacular dwells exist in the world, it is challenging (but desired) to package vernacular architecture traditions and quantitative design knowledge to modern building designers. This project is the first part of a much larger project that intends to create a knowledge base of vernacular building traditions that will include information about not only the energy performance of traditional building techniques, but also address areas of cost, material availability and cultural traditions. (C) 2009 Elsevier B.V. All rights reserved.