Minimum-Impact-House is a holistic approach for the reduction of the overall-impact of residential housing by creating a new type of residential house by densifying the city centre. In the design project a prototype mini-house has been developed to explore the potential of so far uninhabitable urban niches. A triangular site of only 29sqm was chosen to built a Mini-house in size comparable to a family house of 150sqm. This strategy avoids the further use of land and the need of building of new infrastructure like streets and public buildings. The city centre is denser an environment so that the inhabitants won’t to travel so often to work, shopping, education, or cultural events.In a research project the prototype was compared to a typical suburban house. A life-cycle-analysis quantified the amounts of energy, material, and investment for the construction, and consumed during an estimated life-span of the buildings of 50 years. The analysis for which a software was developed was also used as a design-tool for optimising the prototype-building in terms of energy-consumption, construction, and materials. For the building construction renewable resources, mainly timbre, had been used which reduces the energy content and emissions.