Heat, homes and hidden impacts: Life cycle sustainability assessment of low-carbon heating in the built environment

Decarbonising heating in the built environment is one of the most complex challenges in achieving net-zero, yet current research inadequately addresses its full sustainability scope. Existing studies predominantly focus on operational performance while overlooking life cycle impacts, disproportionately emphasise environmental factors, and lack meaningful stakeholder engagement. To address these gaps, this study develops a novel framework integrating Triple Bottom Line sustainability principles, life cycle assessment, and multi-criteria analysis to define what sustainability entails in building heating systems and how it can be evaluated. Applied to eight heating technologies in UK housing, the framework reveals that no single technology dominates across all sustainability dimensions, with significant trade-offs between environmental, economic, and social performance. Heat pumps emerged as the most sustainable option overall, delivering clear environmental and social benefits, though with a challenging economic outlook driven by the unbalanced electricity:gas price ratio. Direct electric systems and biomass boilers ranked poorest, failing to mitigate environmental impacts while inflating life cycle costs and posing broader social burdens, particularly around fuel poverty and public health. This research contributes a practical and transferable assessment framework that integrates life cycle thinking, multidimensional sustainability, and stakeholder priorities into heating system design and decision-making, with broader applicability for informing policy interventions towards a just and sustainable heat transition.