Two different methodologies, one top-down and one bottom-up, are presented for estimating potential future energy demand for space and water heating in the existing building stock of the residential sector to 2030. Two future price scenarios are used as inputs. The work is tested using data for the existing Swedish residential building stock. Compared to 2005 levels of energy use (74 TWh) the bottom-up model shows reductions to 52 TWh and 50 TWh for the two price scenarios, respectively. Results from the top-down model are 11 % (8 TWh) and 7 % (5 TWh) higher than those of the bottom-up model for the two price scenarios. This suggests that the price mechanism alone will not be sufficient to achieve the full techno-economic potential for energy efficiency.