The attention within the communitymoves from sustainability to a healthy society. The loss of health in our society, as a result of aging, lifestyle as well as a creeping loss of attention to the primary requirement of building (i.e. Health improvement), is a major problem. The real-estate world is able to reverse this loss of health by providing healthy environments as a holistic model for the prevention of building and lifestyle related health problems, as well as to support the well-being and performance of people. The real-estate world in that respect has to offer something to the world of health. A healthy environment is of value to people and organizations. By evaluating buildings in the context of sustainability, health and performance of people is an investment in the quality of the work environment, which will result in a reduced environmental impact, better performance, greater well-being and better health. The result is a win-win situation for all participants in the housing process. Today studies and conferences still show that there is room for improvement and that indoor environmental quality is often still poor, despite policy directives, standards and guidelines. This PhD thesis attempts to support finding improvements needed to create a good indoor environment. Much knowledge is available in the literature, but difficult to access for practioners and is hard to translate this knowledge into comparison of different options. This PhD thesis tries to fill a gap between theory and practice. An attempt is made to model a large part of the knowledge that is available in such a way that it will become accessible for the professional practice.