In this study, a 6 storey prefabricated concrete building in Sweden is used as reference to explore life cycle primary energy implications of different frame construction systems under various climate scenarios. The building was redesigned as a low-energy building to the Swedish passive house criteria with frame construction systems in cross laminated timber, prefabricated timber modules and concrete. Using a system perspective approach, we account for relevant energy and material flows linked to the production, construction, operation and end-of-life phases of the building alternatives, including thermal mass effects under recent (2013) as reference and future (2090-2099) climate periods based on representative concentration pathways (RCP) 2.6, 4.5 and 8.5 scenarios. Results show that the buildings' heating and cooling demands vary significantly under the climate scenarios. The timber systems give lower production primary energy and higher biomass residues than the concrete alternative. The concrete system requires slightly lower operation energy due to thermal mass benefits but still, the timber systems give overall lower life cycle primary energy balance. This study shows that low-energy timber buildings with efficient energy supply can play an important role in mitigating climate change for a resource-efficient and sustainable built environment under current and future climate scenarios. © 2019 European Council for an Energy Efficient Economy. All rights reserved.