This handbook provides climatological data which can be used as an input for the design of passive solar buildings and solar systems. Solar radiation data are presented for 37 typical European locations, e.g.: -- monthly average global and direct solar irradiation for several surfaces (types of receiver, orientation and inclination), and -- cumulative frequency and utilizability curves of solar irradiance. Ambient temperature data are presented for 186 European locations as monthly average ambient temperatures and monthly degree-days at several base temperatures. A set of methods and algorithms is also given for the reconstitution of these parameters at places where little information is available. Examples of design tools are introduced. The Handbook has been developed within the framework of a European concerted action entitled EUFRAT. Reference is made to a set of computer programmes and data bases which complement the Handbook in a useful way. The Handbook can easily be used by anyone (scientist, engineer, student or even non-specialist) who needs climatic data for the design of systems.