Effectiveness of building stock sustainability measures in a low-carbon energy system: A scenario analysis for Finland until 2050

Highlights: • Building sector demand-side measures are analysed in broader energy system context. • CO₂ emission reduction potential depends on the carbon intensity of marginal unit. • Marginal emission factor can change during the lifetime of demand-side measure. • System boundaries can significantly affect the results in a low carbon energy system. Energy systems are in a state of transition due to national energy and climate policies. The Finnish Government has declared a national target of achieving carbon neutrality by 2035. This will require further reductions in carbon intensity of the Finnish energy generation mix. Some of the energy related emission reductions could simultaneously be achieved through effective energy efficiency measures in the buildings sector. In this paper, the effectiveness of these measures is studied in alternative long-term energy system scenarios with varying CO₂ reduction targets for the energy supply sector until 2050. The results show that initial carbon intensity of energy mix has a significant effect on the achievable CO₂ emission reductions of demand-side measures. Moreover, assigned system boundaries can significantly affect the results, especially in a low-carbon energy system, where energy savings mostly reduce the use of wood-based biomass in the energy production. Furthermore, long-term perspective for identifying the environmental effects of an energy efficiency measure is recommended, since they often have a long economic lifetime and due to structural changes in the energy system, the marginal energy production unit changes over its lifetime. Consequently, the CO₂ emission reduction potential of an energy efficiency measure can vary over its lifetime.