• Energy Research

Building renovation is urgently required to decrease the energy consumption of the existing building stock and reduce greenhouse gas emissions coming from the building sector. Selecting an appropriate renovation strategy is challenging due to the long building service life and consequent uncertainties. In this paper, we propose a new framework for the robust assessment of renovation strategies in terms of environmental and economic performance of the building's life cycle. First, we identify the possible renovation strategies and define the probability distributions for 74 uncertain parameters. Second, we create an integrated workflow for Life Cycle Assessment (LCA) and Life Cycle Cost analysis (LCC) and make use of Sobol’ indices to identify a prioritization strategy for the renovation. Finally, the selected renovation scenario is assessed by metamodeling techniques to calculate its robustness. The results of three case studies of residential buildings from different construction periods show that the priority in renovation should be given to the heating system replacement, which is followed by the exterior wall insulation and windows. This result is not in agreement with common renovation practices and this discrepancy is discussed at the end of the paper. Building and Environment, 183 ISSN:0360-1323 ISSN:0360-1323

Life Cycle Assessment (LCA) is increasingly used for decision-making in the design process of buildings and neighbourhoods. Therefore, visualisation of LCA results to support interpretation and decision-making becomes more important. The number of building LCA tools and the published literature has increased substantially in recent years. Most of them include some type of visualisation. However, there are currently no clear guidelines and no harmonised way of presenting LCA results. In this paper, we review the current state of the art in visualising LCA results to provide a structured overview. Furthermore, we discuss recent and potential future developments. The review results show a great variety in visualisation options. By matching them with common LCA goals we provide a structured basis for future developments. Case studies combining different kinds of visualisations within the design environment, interactive dashboards, and immersive technologies, such as virtual reality, show a big potential for facilitating the interpretation of LCA results and collaborative design processes. The overview and recommendations presented in this paper provide a basis for future development of intuitive and design-integrated visualisation of LCA results to support decision-making. Building and Environment, 190 ISSN:0360-1323 ISSN:0360-1323

Curbing embodied emissions is essential for reducing greenhouse gas emissions. In the building construction sector, bio-based materials have shown promising solutions in reducing embodied emissions while offering carbon storage potential. This study presents a framework to assess the potential of biogenic carbon storage at the urban scale. A district in Zurich, Switzerland, is selected as the case study, incorporating Swiss-based life cycle data for building construction along with current and projected grid carbon intensities. Our work expands the CityEnergyAnalyst tool to include biogenic carbon data in building archetypes. The effects of retrofit on operational and embodied emissions are evaluated using three representative scenarios: low, intermediate, and intensive retrofit rates. The embodied emissions and the potential for carbon storage are assessed by comparing conventional, low-carbon, and carbon-negative materials. The temporal patterns of emissions show that grid decarbonization and building electrification are essential for reaching net-zero emissions by 2060. Furthermore, increasing the retrofit rate notably curbs operational emissions regardless of the grid decarbonization scenario. For instance, increasing the retrofit rate from 1.0 % to 1.9 % could reduce operational emissions by 16 %. Retrofitting the walls alone could store up to 360 ktCO2 eq. in a district of approximately 2200 buildings. The study underlines that the properties of a carbon-negative material—such as its conductivity and density—play a significant role in biogenic carbon storage capabilities. The findings indicate that a carbon-negative material could boost biogenic carbon storage six-fold compared to low-carbon alternatives. Sustainable Cities and Society, 125 ISSN:2210-6707

To fully analyze the potential of PVs in achieving sustainable energy goals, careful consideration of the life cycle including the embodied impact is needed. Despite the existence of various life cycle inventories for PV modules, there remains a lack of structured and detailed data to enable easy comparison across different technology configurations. Such data is crucial for identifying the components with the highest environmental impact and further optimization. This data gap is an obstacle to informed decision-making processes when evaluating PV designs. The goal of this study is to develop a harmonized, modular database that captures the environmental impact of various PV systems in high resolution. It includes the selection of cell technology, electrical components, frame materials, and the location of production. The environmental assessment includes 14 impact categories. Additionally, a web-based configurator is available, allowing users to quickly estimate the environmental impact of custom PV panels. Through exhaustive sampling of different configurations, the study demonstrates that the Global Warming Potential of a PV panel can range from 10 to 380 kgCO2eq/sqm. The results of this study can support architects, engineers, and planners in estimating the embodied impact of the PV systems, leading to more informed and environmentally conscious design decisions. Renewable Energy, 236 ISSN:0960-1481 ISSN:1879-0682