The aim of the paper is to investigate the possibilities of combining the current Danish Energy Frame calculation based on the Energy Performance of Buildings Directive with an hourly building energy simulation. The paper will analyze the early phases of the building design process where the first sketches are drawn and the energy frame is calculated. As part of this process there are many possibilities of optimizing the building to achieve low energy use and good thermal indoor climate. However presently, the tools that can be used for this optimization cannot at the same time do the energy frame calculation. Therefore the paper will describe a method for combining these two calculations. In practise the BuildDesk Expert program, which can be used to calculated the Danish Energy Frame, will be used together with the program IDBuild, which a tool for optimization of the energy use and indoor climate, to design an office building. The conclusion of the paper is that the method presented here can be used to ensure that the energy consumption can be kept low at the same time that the building can have good indoor climate.