The aim of the study was to define an energy supply solutions for a low-energy commercial building in cold climates. A new low-energy office building built with high quality building insulation better than the Norwegian passive building standard was analyzed by using EnergyPlus. The results showed that the heat pump solutions could be used to cover the building base load, while the peak load should be covered by additional energy sources. Due to a high indoor temperature caused by the high quality building insulation standard, an increase in ventilation air flow was necessary during the summer. To fully utilize the heat pump technology possibilities and avoid unnecessary use of the electric boiler, the control strategy without night setback was preferable. The techno-economic analysis showed that the best energy supply solution seemed to be an air-to-water heat pump without solar assistance, while a 50% increase in the energy price could make the solution with the solar collector economically attractive. A similar trend might be noticed for other building types under the same economic conditions, because the relative ratio between the savings and the total energy use would be similar.