IMPACT OF BUILDING REFURBISHMENT STRATEGIES ON THE ENERGETIC PAYBACK

The target of the International Energy Agency (IEA) and the European Commission
(EC) is to achieve a reduction of 80% for global greenhouse gas (GHG) emissions by 2050. Buildings account worldwide for 40% of global energy consumption and 30% of GHG emission. Due to the fact that the building stock plays a key role in achieving these targets, the aim of the paper is to find an optimal refurbishment strategy in terms of lowest environmental impact through life cycle assessment (LCA). Three façade refurbishment scenarios (none, minimum and energetic high quality) and onsite energy generation (solar thermal and photovoltaic panel (PV)) were evaluated. We applied and verified the proposed approach on a residential case study as reference refurbishment project built in the 1960s. The environmental indicators cumulative energy demand, global warming potential and ecological scarcity were evaluated for the LCA covering all life cycle stages over a reference study period of 60 years. The results showed that the optimal refurbishment scenario from an LCA perspective was a high-quality refurbishment of the thermal envelope by the use of prefabricated façade elements, solar thermal collectors as also photovoltaic panels. In terms of the
assessed environmental indicators, this refurbishment scenario will always be
beneficial due to its lowest impact throughout the life cycle. However, the sensitivity analysis on the high-quality refurbishment strategies determined that a surplus of electricity production by increasing the PV area is not always feasible as the operational impact burdens react with great sensitivity to changes in the electricity mix towards more renewable resources, likely to occur in the near future. It is thus necessary to find an optimum balance between diminishing returns over time and financial investment over the entire life cycles of buildings, especially for plus-energy buildings.