DesignBuilder Software Ltd. (DBS) teams up with De Montfort University (DMU) and Zero Energy Design Ltd. (ZED) in the research and development of innovative building performance simulation software that can be used to assist design decision making in all stages of the life cycle of low impact buildings. The most significant innovations include: (1) the concept of “one tool, multiple user interface” to meet the demand of different target audiences; (2) the first commercial software with a robust algorithmic optimisation capability suitable for selecting practical cost-effective energy-saving measures; and (3) a new on-line service-based business model that would help build a user community and provide easy access to design guidance and facilities. The primary output of the project will be a low impact building design/decision tool capable of identifying a range of optimal design configurations. The tool will be accessible and useful for a number of industry user groups from architects through property owners to occupants. The new software will be based on DBS's existing industry-leading product, DesignBuilder v3. The specialities of the academic partner (DMU), i.e. cutting-edge optimisation technologies and knowledge of existing UK building stock, plus ZED's expertise in delivering low impact building design, will be integrated in the new tool. In addition to the new user interfaces and the optimisation engine, a library of components and templates, cost and carbon emission models, as well as a prototype of the on-line service platform, will be researched and developed.