Both the current and future buildings will have very well-insulated building envelopes heated mostly by internal heat gains from occupants and household electricity. The occupant related energy uses, household electricity and domestic hot water heating, will have a large impact on the energy performance. In low-energy buildings the heating of domestic hot water is in the same order of magnitude as the energy for space heating. Knowledge of occupancy levels is critical for prediction and verification as well as optimization of various demand controlled systems. This article presents how household electricity and domestic hot water use varies due to occupancy level. Occupancy level, household electricity and domestic hot water were measured in 79 apartments during 12 days per apartment. Occupancy level was measured by electronic diaries in which those living in and visiting the apartment marked their attendance by pressing buttons when entering and leaving the apartment. Household electricity and domestic hot water were measured hourly while the diaries recorded data every second. The result shows that there are relatively weak correlations between occupancy level and the studied energy uses demonstrated by a large variation in both household electricity and hot water use at the same occupancy level.