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The existing building patrimony is responsible for 36% of the global energy use and 37% of the greenhouse gas emissions. It is hence a major challenge to improve its energy performance. According to the Renovation Wave, the average annual renovation rate should be doubled by 2030 up to 3% and deep energy renovations should be encouraged. The Belgian city of Leuven works towards this target and is even more ambitious, setting their goal on becoming climate neutral by 2050. The strategy investigated in this study is to increase the renovation rate by clustering renovations, which is challenging since the Belgian building stock is highly privatised. Based on a thorough literature study, this paper examines various methodologies for building stock modelling. The main focus is comparing the required input data with the data availability, handling the data gaps, and defining their influence on the model’s accuracy. The findings are applied to Leuven by analysing the main drivers to cluster renovation measures. However, many data gaps appeared, leading to the selection of a GIS-enhanced archetype model enriched by energy data as the most suitable approach. To avoid misinterpretation due to differences in data quality, transparent reporting in stock modelling is recommended.

To date, many cities have engaged in efforts to become more sustainable. These efforts often are translated into measures to reduce their greenhouse gas (GHG) emissions, leading to a proliferation of standards and methods. Discrepancies exist between these various accounting approaches in terms of the definition of system boundaries, allocation procedures, quality of data, and the reporting and verification of results. This paper examines some of the most important theoretical and practical issues and challenges of urban-related GHG accounting and highlights how existing approaches deal with these. Three different GHG emission accounting standards are compared and critically analysed: the Global Protocol for Community-Scale Greenhouse Gas Emissions (GPC), Bilan Carbone and ISO 14064-1:2018. The Organizational Environmental Footprint (OEF) and a previous analysis about footprinting performed by the European Commission are used as analytical lenses. Based on this analysis, suggestions are made for enhancing comprehensiveness and transparency, and providing guidelines for driving cities towards a more low-carbon path. PRACTICE RELEVANCE This critical analysis shows that each method has strong points, but practical issues remain for urban stakeholders undertaking GHG emissions inventories. First, the uniqueness of each urban system needs to be addressed in the goal and scope phase in order to provide meaningful terms of comparison between cities. The creation of different categories to provide similar clusters of cities would enable a more meaningful cross-city comparison as well as a proper formulation of targeted policies. Second, the inclusion of a life-cycle perspective in GHG accounting is essential for avoiding the risk of burdenshifting. Both production and consumption approaches are crucial in supporting the objectives of decarbonisation and the carbon neutrality of cities. If both perspectives are not acknowledged, ‘climate neutral’ targets can be misleading and impact negatively on decision-making and behavioural change of producers and consumers.

Energy consumption of buildings is one of the major drivers of environmental impacts. Life cycle assessment (LCA) may support the assessment of burdens and benefits associated to eco-innovations aiming at reducing these environmental impacts. Energy efficiency policies however typically focus on the meso- or macro-scale, while interventions are typically taken at the micro-scale. This paper presents an approach that bridges this gap by using the results of energy simulations and LCA studies at the building level to estimate the effect of micro-scale eco-innovations on the macro-scale, i.e. the housing stock in Europe. LCA and dynamic energy simulations are integrated to accurately assess the life cycle environmental burdens and benefits of eco-innovation measures at the building level. This allows quantitatively assessing the effectiveness of these measures to lower the energy use and environmental impact of buildings. The analysis at this micro-scale focuses on 24 representative residential buildings within the EU. For the upscaling to the EU housing stock, a hybrid approach is used. The results of the micro-scale analysis are upscaled to the EU housing stock scale by adopting the eco-innovation measures to (part of) the EU building stock (bottom–up approach) and extrapolating the relative impact reduction obtained for the reference buildings to the baseline stock model. The reference buildings in the baseline stock model have been developed by European Commission-Joint Research Centre based on a statistical analysis (top–down approach) of the European housing stock. The method is used to evaluate five scenarios covering various aspects: building components (building envelope insulation), technical installations (renewable energy), user behaviour (night setback of the setpoint temperature), and a combined scenario. Results show that the proposed combination of bottom–up and top–down approaches allow accurately assessing the impact of eco-innovation measures at the macro-scale. The results indicate that a combination of policy measures is necessary to lower the environmental impacts of the building stock to a significative extent. Interventions addressing energy efficiency at building level may lead to the need of a trade-off between resource efficiency and environmental impacts. LCA integrated with dynamic energy simulation may help unveiling the potential improvements and burdens associated to eco-innovations.

With the aim of moving towards a more sustainable society, hospital buildings are challenged to decrease their environmental impact while continuing to offer affordable and qualitative medical care. The aim of this paper was to gain insight into the main drivers of the environmental impacts and costs of healthcare facilities, and to identify methodological obstacles for a quantitative assessment. More specifically, the objective was to assess the environmental and financial impacts of the general hospital Sint Maarten in Mechelen (Belgium) by using a life cycle approach. The hospital building was analyzed based on a combination of a simplified life cycle assessment and life cycle costing. The “MMG+_KULeuven” assessment tool was used for the calculation of environmental impacts and financial costs. The study revealed that the environmental impact was mainly caused by electricity use for appliances and lighting, cleaning processes, material production, and spatial heating, while building construction and electricity use caused the highest financial costs. The most relevant impact categories identified were global warming, eutrophication, acidification, human toxicity (cancer and non-cancer effects), and particulate matter. Various methodological challenges were identified, such as the adaptation of existing methods to ensure applicability to hospital buildings and the extraction of data from a Revit model.

AbstractThe emphasis in this research is on affordable and innovative semi-prefabricated ‘open-renovation-systems’ for extending residential buildings. Based on an existing LCA (life cycle assessment) and LCC (life cycle costing) methodology, two methodological issues in evaluating renovation interventions are assessed: (1) the allocation of the environmental impact of the existing structures and materials to the life cycle before and after renovation and (2) the energy calculation method. An existing semi-prefabricated ‘open-renovation-system’ for a rooftop extension is assessed both on element and building level from an environmental and financial life cycle perspective.

Abstract The building sector is well known as one of the significant contributors to climate change. The use of materials and energy are important drivers, both during construction and the whole life cycle. This study is part of a research to improve the Belgian national approach of life cycle environmental assessment for buildings. The current approach focusses mainly on material use, and the operational energy is estimated via the equivalent degree day method assuming a fixed value of 1200 equivalent heating degree days per year. This paper extends this widespread degree day approach to improve its accuracy by including the effect of various parameters (climate, building characteristics, obstructions by the environment, occupant behaviour). Step by step user-friendly input and graphical feedback is moreover considered necessary for designers and has been added. The annual heating energy estimated by our proposed semi-dynamic model has been validated by dynamic energy simulations using EnergyPlus of 8000 randomly generated cases. Both results have been plotted in a 2D graph. The slope of the linear regression through the origin is 0.8955, and the R-square value is 0.9058. Based on this comparison, it is concluded that the semi-dynamic model, with simplified input and fast results, has sufficient accuracy for the first design phases compared to the dynamic model.

Net zero energy buildings (NZEBs) are energy efficient buildings that incorporate renewable energy generation systems so as to produce sufficient renewable energy to at least offset the total amount of non-renewable energy used by the building on an annual basis. NZEB technologies have widespread commercial and residential application, but their feasibility and efficacy in the livestock sector in support of sustainable intensification have received little attention. This study quantifies the potential for such technologies to improve sustainability outcomes in the livestock sector based on an ISO 14044-compliant life cycle assessment of a pilot net zero energy laying hen facility in Alberta, Canada compared to a conventional facility. It was found that direct energy inputs account for 6.47% and 31.64% of the life cycle cumulative energy use of egg production in NZE and non-NZE hen housing, respectively. Average infrastructure-related contributions to the life cycle impacts of egg production are only 4.34% and 1.94% for the NZE and non-NZE barns, but NZE technologies reduce the net impacts of egg production by 0.89–64.82%. The environmental impact payback time for the NZE barn (30-year lifespan) ranges from 1.38 to 20.66 years, considering the largely fossil fuel-based electricity grid in Alberta, which indicates that non-trivial environmental benefits would accrue across impact categories considered. However, this could vary considerably elsewhere depending on the types and amounts of green energy utilized in regional grid mixes. The type and availability of renewable energy resources that are integrated into NZE barns will similarly be important in determining the potential of such technologies to support sustainable intensification in this sector.