This step is aimed at defining the technical features of the solar cooling systems thanks to the information of the project. To reach this goal, several tools are to be assembled together for a coherent and optimal process of sizing : a load generator permitting to create load files from a basic description of the targeted building and a simplified sizing tool giving the simulated performances of a proposed system in accordance with the building conditions and the climate. The load generator developed by Fraunhofer ISE in the framework of the PolySMART© [3] E. U project could be used for example thanks to some specific developments. Beside, an internal tool from TECSOL or the SACE tool [4] could permit to make a quantitative design of the solar cooling systems : definition of the main components, energy balance, primary energy savings, presentation of the energy results in a synthetic sheet.