As requirements regarding energy efficiency are getting tougher, buildings in the arctic, as well as the rest of the world, need to be more energy efficient without compromising a good indoor climate. This paper presents measured moisture supply and occupancy level in a Swedish Arctic multi-family building. Measurements were done during one year with readings every 30 minutes in a building consisting of 51 apartments located in Kiruna at latitude 67.9°. Averages and typical variations on different timescales, year and day are presented for the different parameters as well as correlations between the parameters, for example moisture supply as a function of occupancy level. The results can be used when input data for simulations of energy use, moisture conditions and indoor climate are chosen as well as a reference to compare measurements to during verifications. In energy efficient buildings the occupants’ behavior generally has a high impact on the building performance which means that the characteristics of behavior related parameters are important to know.