Abstract Energy monitoring has been performed for two passive houses in Oslo during 2012-2013. One house is heated by a solar heating system, the other with an air-to-water heat pump. The objective has been to investigate the need for additional energy supply in order to provide the required indoor comfort and prepare domestic hot water. If corrected for differences in domestic hot water consumption and indoor temperature the two houses require almost equal amounts of auxiliary energy. The solar energy gain would increase significantly if the solar collectors were placed more appropriate, with less shading due to neighboring buildings and vegetation. Both heating technologies could improve performance with minor system adaptations. It was shown that solar thermal heating can compete with heat pump techology even for locations as far north as Oslo, Norway.