## 2 Literature Review
### Life Cycle Thinking
The findings from the Norwegian ZEB case studies (four new buildings, two concept studies, and one refurbishment building) showed that the embodied impact of ZEBs ranges between 55 and 87% from A1 to A3 and B4, 2 and 15% from A4 to A5, and ca 8% from C1 to C4 [42], whilst the operational impact represented 14-42%. The LCA study from the IEA EBC Annex 57 (Annex 57) on 80 building case studies (where 11 refurbished buildings were included) found that the production phase dominates total GHG emissions, with 64% of GHG emissions, followed by replacements at 22% and end of life at 14% [40]. Existing studies also indicate the potential environmental benefits from refurbishment of existing buildings in the range between 4 and 74% depending on the scenarios considered in the studies. [PERSON] and [PERSON] [45] indicated a 28-33% impact reduction from the selective deconstruction and reuse of a thirteen-story library tower at the University of Calgary, in Western Canada, in seven environmental impact categories assessed (eutrophication potential, smog potential, global warming potential, fossil fuel consumption, human health criteria, acidification potential, and ozone depletion). [PERSON] and [PERSON] also pointed out the importance of comparative assessments for reuse vs. new construction regardless of the challenges due to the uniqueness of different buildings and their locations. [PERSON] et al. [46] showed 36-75% impact reductions across six environmental impact indicators (acidification potential, eutrophication potential, global warming potential, ozone depletion potential, smog formation potential, and non-renewable energy demand) when refurbishment of an office building was compared to new construction. [PERSON] et al. [46] also addressed the challenges related to the lack of a clear system boundary description regarding life cycle modules included in existing buildings and refurbishment projects. The study performed by Preservation Green Lab [47] on six building typologies from four US cities showed about a 4 to 46% environmental impact saving from renovation and reuse of existing building rather than demolishing and constructing new buildings. Preservation Green Lab [47] discussed the potential dependency of impacts from the energy performance of upgrading associated with material choices. [PERSON] [48] discussed the dependency of operational energy use on the sources of energy and the associated emission factors and highlighted the importance of embodied GHG emissions. Even if refurbishment and adaptive reuse of existing buildings have been suggested for reducing embodied impacts [46], only a few LCA studies focus on the evaluation of the environmental performance of refurbishment and adaptive reuse of the existing building stock [49], and even fewer studies consider embodied impacts and evaluate the contribution of cultural and heritage values [16; 22; 46; 50]. For example, from the 80 studies evaluated under Annex 57, only 11 were existing buildings [40]. The results from the first LCA benchmark study conducted in Norway also show similar findings, as from over 120 studies collected, only 13 were for existing buildings, and only 2 of the 13 studies presented the results from a historic building. The results in both Annex 57 and the Norwegian studies indicate the impact from refurbishment projects, which is under half that of new building projects. Developing LCA benchmarking for existing buildings, based on a harmonized methodology, will increase the transparency and repeatability of LCA results and enable different user groups to make informed decisions. Interventions to reduce emissions will often affect heritage values if special considerations are not taken into account [20]. When restoring or preserving legally protectedbuildings in Norway, value assessments always form the basis for measures permitted by the cultural heritage authorities [12]. In Norway, the cultural heritage authorities also want buildings without formal protection to be treated in accordance with their heritage values [51].