Buildings are inherently linked to their usage and surroundings and hence their indoor environment is the result of a range of interactions affected by seasonal and daily changes in climate and by the requirements of occupants varying in time and space. The design of buildings in the mid-late twentieth century has sought to eliminate the effect of outdoor daily and seasonal changes through the use of extensive heating, cooling, lighting and ventilation equipment, resulting in spiraling energy consumption and environmental impact. Energy used in buildings accounts for almost half of the total amount of energy consumed in the European Community today. Almost 85% of the energy used in buildings is for low temperature applications such as space and water heating. Appropriate building designs involving clean and efficient technologies are already available and there use may help to reduce future energy consumption as well as to provide a better quality of life for citizens.