The definition of sustainable building design is very often connected with energy efficiency. European Union is one of the big drivers behind the concept “Nearly Zero Energy building”, a requirement which all new buildings must meet after the year 2020. There are several other qualification systems that demands figures on noise reduction, indoor climate, sun shading and so on. However, regulations on the material use or diverse ways of construction are seldom mentioned. In this thesis I am reflecting about the popular focus of energy efficiency and going deeper into the understanding of what an ecological sustainable building should be defined as. This is done by interviewing practicing architects within the field and by researching different material properties and building techniques. The findings are visualized through a villa design which is showcased parallel to the research. The design process is influenced by the information gathered in the research process and the final design is the conclusion of my findings. In the end, there is a discussion whether it is necessary to focus mainly on energy efficiency of buildings or if there should be more emphasis on the construction and demolition phase, material usage and maintenance of the building, which are all very critical issues concerning sustainable building design
