The aim of this master`s thesis was to study environmentally friendly energy-efficient solutions, which can be utilized in the renovation and construction project of Kymenlaakso Central Hospital. Investment potential was calculated from cost savings due to energy-efficient solutions. The investment potential can be used in a part of the financing of investment project. The thesis is divided into theoretical literature review and empirical part. The empirical part is an action-oriented case study.

Three scenarios based on reduction in energy consumption were formulated to define investment potential. The scenarios based on different methods to reduce energy consumption, results of researches and existing renovation project. The scenarios included the unequal combinations of electricity and heating energy reductions. The investment potential was produced by calculating the net present value of the future cost saving of energy consumption. As the results of study methods for developing energy efficiency were introduced and three variations of investment potential were produced. The results can be utilized in the goal setting and the investment appraisal of the design of renovation project.