Life Cycle Sustainability Assessment of Energy renovations. A case-study of a multi-family building in Sweden

Abstract: Various renovations were applied to the existing post-war building stock of the so called “Swedish Million Program”, that were built during the 1965 and 1974 period. Only 20% of those buildings were renovated and still the rest of them remains in need of vast renovations, to mitigate the climatic impact of the existing building stock. Nowadays, the annual rate of large-scale renovation in EU countries including Sweden is only 0.4% to 1.2% per year. Consequently, there is a great need for large-scale renovations and due to the building’s high energy demand, the EU policies are driving the legislations and regulations towards decreasing the environmental impact towards climate neutrality by 2050 for EU and 2045 for Sweden. A building in South Sweden, from the Swedish Million Program was used as a case-study building, to apply several renovation solutions. The renovations were analysed from the economic but also from the environmental perspective. Three renovation packages were applied: envelope renovation, ventilation with heat recovery, and deep renovation. With Life Cycle Cost analysis, the investment and the operational costs were calculated using the Net Present Value and Life Cycle Profit. Then the Life Cycle Assessment was conducted, by using the shadow cost, i.e. a monetization value associated with the potential environmental impacts caused by the building. In the end the economic and environmental results were combined into one accumulated result into the Life Cycle Sustainability Assessment (LCSA) and to draw conclusions from the results. It was found that the energy renovations were, in most cases, not profitable from the economic point of view. The heat recovery case resulted in a positive Life Cycle Profit and the cases with a negative Life Cycle Profit were the envelope renovation and the deep renovation. On the other hand, from the environmental perspective, all energy renovations were beneficial, due to the lower environmental impact, i.e. shadow cost, compared to the base case building. So, from the Life Cycle Sustainability Assessment, from the combination and the contribution of both the economic and environmental results, it was found that the heat recovery case was a profitable investment from both aspects. The LCSA results of the other cases, were resulted having higher values compared to the base case, since the LCC results dominated the LCA results, due to their high investments. Consequently, the LCC in the present study is determinant in the decision process. This kind of Life Cycle Sustainability Assessment would benefit the countries to the decision-making process on applying sustainable renovations to the existing building stock.