Low energy buildings have well insulated building enclosures and efficient ventilation heat recovery systems which lead to small transmission and ventilation heat losses. During a large part of the year internal heat gains from people, household electricity and solar heat gains balance the heat losses with zero heating need as a result. All energy uses in a building are part of the buildings energy balance and for example the heat gains from a higher use of household electricity should result in a lower use of heating given that the heating control systems work as intended. Different user characteristics will result in different heating demand in the same building, and in low energy buildings different user characteristics will have a relatively higher impact compared to a less energy efficient buildings. Household electricity and domestic hot water was measured during one year in 520 one bedroom apartments and 462 two bedroom apartments in Sweden. The average annual use of household electricity was 27.7 kWh/m² in one bedroom apartments and 29.1 kWh/m² in two bedroom apartments. The use varied between almost zero and 90 kWh/m2 in the different apartments. Average annual domestic hot water heating was 20.1 kWh/m² in one bedroom apartments and 22.8 kWh/m² in two bedroom apartments. The use varied between zero and 140 kWh/m². The correlation between household electricity and domestic hot water was studied and different user scenarios were defined. The user scenarios were used as input data for simulations of heating demand in order to study different users' impact on the heating demand in buildings with different characteristics. The result shows that the users can have a strong impact on a buildings heating demand and in order to determine the impact that different users will have, it must be analyzed based on the actual building since it is determined not only by the user related energies but also by the building's characteristics.