Tor Broström is a Professor in Conservation at Uppsala University, Campus Gotland, Sweden. With a background in engineering, his research focuses on indoor climate and energy conservation in historic buildings. He is coordinator of the Swedish national research programme on energy efficiency in historic buildings. Petra Eriksson, is a lecturer and PhD candidate in conservation at Uppsala University, Campus Gotland, Sweden. Petra has a background in the applied field of conservation and her research is in the field of heritage conservation in relation to energy efficiency. Linn Liu is a PhD candidate in the Division of Energy Systems, Department of Management and Engineering at Linköping University, Sweden. Her research area is within energy efficiency and cost efficiency of multifamily buildings and historic buildings. Patrik Rohdin is Associate Professor in the Division of Energy Systems, Department of Management and Engineering at Linköping University, Sweden. Patrik is conducting research related to energy efficiency in the built environment and building simulation and is active within the national interdisciplinary research programme, program energy systems. Bahram Moshfegh is a Professor and Head of the Division of Energy Systems, Department of Management and Engineering at Linköping University, Sweden. Professor Moshfegh has been active in the following research areas: mathematical modelling and measuring techniques for air and energy flow in buildings, energy-efficient HVAC systems and local and regional energy systems. Fredrik Ståhl is Senior Researcher in the Department of Energy Technology at SP Swedish Technical Research Institute. Currently, his research is focused on energy efficiency in historic buildings. The Swedish research project 'Potential and Policies for Energy Efficiency in Swedish Historic Buildings' aims to investigate the interdependency between political energy targets and effects on the built heritage. The fi rst part of this paper presents an iterative and interactive method to assess the potential for and consequences of improving the energy performance in a stock of historic buildings. Key elements in the method are: categorisation of the building stock, identifying targets, assessment of measures, and life-cycle cost optimisation. In the second part of the paper, the method is applied to a typical Swedish building. The selected case study shows how the method allows for an interaction between the quantitative assessment of the technoeconomic optimisation and the qualitative assessment of vulnerability and other risks. Through a multidisciplinary dialogue and iteration it is possible to arrive at a solution that best balances energy conservation and building conservation in a given decision context.