In this thesis a simulation program originally designed for simulation of heating demand and solar heating potential for buildings (SolDat) is developed to also beused for cooling purposes (SolEC). SolDat is capable of weather simulation. Therefore it is focused on developing statistical weather models, which in a better waycan generate the weather variables.Currently SolDat simulates normalized clearness index, ambient temperature and cold water temperature. For solar heating simulations this is adequate. For simulation of radiative cooling, however, the additional variables cloud cover, cloudbase height and dew point temperature must be introduced. Models for these variables are developed and tested.In addition, the model for clear weather index is enhanced by an addition of datafrom solar radiation measurements from 33 weather stations throughout Norway.Using these data, Norway is divided into ﬁve climatic zones. This means that theweather can be simulated based on local climate of the location in question.A model for cooling demand calculation is implemented in SolEC and currentlyworking. Implementation of radiative heat loss for cooling purposes is attempted,but failed due to lack of time.