To be successful, building design needs sufficient feedback at each decision making step. A large number of alternatives should thereby be produced and analyzed to find the optimal solution(s). In the energy domain, there are two significant limiting factors for the efficient evaluation of such design alternatives: the huge simulation time effort needed, and the difficulties to analyze the extensive amount of output data. This paper presents an approach enabling the handling of both limiting aspects: simulation effort reduction via a multi-step procedure, and results assessment via multi-eKPI (energy-related Key Performance Indicators) analysis. Simulations are performed on three levels, passive evaluation to detect exemplary zones, zone level assessment to detect most influencing parameters and multi-zone (building level) evaluation to identify promising design alternatives for the entire building. Depending on the project aims, results analysis can be done for different indicator values, suitable to rate indoor environment, energy consumption, peak loads and other properties of the building. These eKPIs provide an efficient approach to compare and filter design alternatives. By introducing the new multi-eKPI analysis method and prototype tools the number of analyzed alternatives can increase from 100 up to 10000x compared to the current situation. The decision making process is thereby supported by visual functionalities for filtering, comparing and correlating data.