The aim of this study is to provide a basic introduction to the application of life cycle thinking in building design. This is achieved through the development of a basic MS Excel tool, and applying it to a specific case study. The application of the tool to a new building is intended to illustrate its practical application and its potential as a basis for the choice of energy system and building technology with low environmental impact. The building, Gronskar, referred to in the case study was built by Skanska in Sweden, and is based on the “Moderna hus” concept, with the underlying principle of designing and constructing new efficient residential buildings. The tool is also intended to offer the necessary flexibility in view of the specific circumstances of different countries and available data.  Furthermore the platform chosen allows for potential further development by users.