Heat pumps for space heating and domestic hot water production in residential buildings, an environmental comparison in a present and future scenario

•The use of green hydrogen was explored with a Life Cycle approach.•3 energy systems were compared based on 16 environmental impact categories.•Result uncertainties were investigated via error propagation.•The use phase contributes 91 % of the impact of the three energy systems.•The gas heat pump shows a lower climate profile in the short-term future scenario.