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Buildings represent 40% of the European Union’s final energy consumption and are largely of resi- dential use. From 2006 to 2016, existing European housing stocks have been analysed at national level to make the energy refurbishment processes transparent and effective. However, at the meta- scale of regions, cities or neighbourhoods, case-by-case analysis using Building Energy Models (BEM) becomes an unfeasible decision-support tool. To try to overcome this limitation, the nascent field of Urban Building Energy Modelling (UBEM) is making substantial progress in the assessment of build- ing energy performance at urban scale. Still, most of the UBEM projects rely upon archetypes – i.e. virtual or sample buildings illustrative of the most frequent characteristics of a particular category, and the definition and description of such archetypes may compromise their reliability. This paper presents an alternative UBEM approach, especially designed for the homogeneous historic districts of cities where a significant proportion of the buildings are under preservation rules. These rules can restrict the scope of the measures to improve their energy efficiency or limit the possibility of implementing renewable energy systems. We introduce a new parameter (HAD) to classify blocks according to their heritage asset density. HAD is then mapped onto the study-area and the sample block is selected as representative of the most frequent HAD category. Using the historic ensemble of Seville as case-study, this paper shows results in energy consumption on a district scale and proposes a set of solutions to improve the energy efficiency of the buildings while respecting the heritage preservation rules. To sup- port consistent policy decisions, validation of these results has been carried out, by in-situ monitoring of a representative number of dwellings.

This study proposes a combined life cycle assessment (LCA) and Geographical Information Systems (GIS) methodology to develop complex LCA inventories for multiple applications. The study focusses on the environmental implications of buildings retrofits, especially in the European context, where the building sector is one of the largest energy consumers. In this context, a new and holistic perspective is needed that expands from the building scale to the urban scale. The combination of LCA and GIS methods includes the development of an urban characterization model based on bottom-up methodologies. The environmental implications associated with increasing the thermal insulation of existing buildings to the current standard are determined based on LCA methods. In this step, common construction systems for building retrofits are used, and insulation materials are compared. Then, absolute and relative extrapolations are performed considering different urban morphologies. The results confirm the importance of the energy retrofitting of residential buildings in large functional urban areas such as the Barcelona metropolitan area, which is examined as a case study. The LCA results indicate that the selection of proper construction systems and thermal insulation materials is important to the environmental performance of building retrofits, and these selections can lead to CO2 emission differences of up 16% in the region. The relative extrapolation results indicate significant environmental differences between urban morphologies. The LCA results show the potential strategic impacts of the inclusion of LCA methods in retrofit policies at the urban scale.

In 2020, domestic buildings represented 27% of the energy consumption in the European Union. The EC Renovation Wave concluded that the annual renovation rate should be doubled, from 1% to 2%, over the next decade in order to meet the 2030 energy efficiency targets. Funding programs are being implemented at national and European levels to accelerate this process. These aim to prioritize large-scale interventions and the most efficient energy conservation measures by including strict performance targets as eligibility conditions. However, these programs are coordinated by local authorities, and they struggle to generate reliable energy estimates for large areas, not least predict potential savings at both aggregated and individual levels. This paper presents a bespoke energy retrofit analysis methodology based on urban building energy modelling, which is defined and calibrated with the Energy Performance Certificate Database. We apply this method to the case study Barrio das Flores. The model adopts a hybrid approach, defining and simulating representative typologies to extrapolate the results to the whole district according to each dwelling’s specific parameters. This methodology will be used to predict the potential energy savings in the study area and support the grant application for the funding renovation program.

The link between urban form and building energy demand is a complex balance of morphological, constructive, utilization and climatic factor. Especially in the European compact city, where existing areas prevail on much more energy-efficient new settlements, it is evident that operative ways to transform efficiently the building stock have to be found. This paper explores the existence of a relation between built mass and energy demand depending on urban form. Focusing on the compact city of Mediterranean climate, tests on different case studies simulations are carried out. Results presented and discussed, point out that mass has strong relevance on energy demand and plays an important role in reducing energy consumptions. This paper is a preliminary report of an ongoing research study about one possible way to comprehend “metabolic rate” scaling law - the relationship between power and mass of a complex system in its process - concerning urban fabric. This knowledge-base could help verify the accordance with this rule on urban scale and give hints to conscious and effective built environment transformations towards more efficient conditions.

Current plans to combat the environmental global impact of the building sector have encouraged research on sustainable actions for increasing the renovation rate of many buildings whose performance is far from meeting current energy standards. This paper presents a protocol for analysing the existing residential stock towards planning building upgrading actions. A Geographic Information System with building-related data is used to assess the housing stock following a bottom-up approach. The urban study sample is established using several criteria at building level. The potential for improvement of buildings is ascertained using DOE 2.2 energy models which incorporate standard passive strategies to reduce the current primary energy demand and the associated CO2 emissions. The protocol is applied to the existing public housing developments built in the southern Spanish city of Córdoba, under Mediterranean conditions, during the urban expansion period which spanned 1951–1980. The extrapolation of results to the urban study sample shows a 25 % reduction in CO2 emissions and a 40 % decrease in annual energy demand. Furthermore, the impact of typology and position on the energy behaviour of a given building is acknowledged. The benefits achieved aim to help stakeholders in the implementation of energy retrofitting urban plans.

Unidad de excelencia María de Maeztu MdM-2015-0552 This study proposes a combined life cycle assessment (LCA) and Geographical Information Systems (GIS) methodology to develop complex LCA inventories for multiple applications. The study focusses on the environmental implications of buildings retrofits, especially in the European context, where the building sector is one of the largest energy consumers. In this context, a new and holistic perspective is needed that expands from the building scale to the urban scale. The combination of LCA and GIS methods includes the development of an urban characterization model based on bottom-up methodologies. The environmental implications associated with increasing the thermal insulation of existing buildings to the current standard are determined based on LCA methods. In this step, common construction systems for building retrofits are used, and insulation materials are compared. Then, absolute and relative extrapolations are performed considering different urban morphologies. The results confirm the importance of the energy retrofitting of residential buildings in large functional urban areas such as the Barcelona metropolitan area, which is examined as a case study. The LCA results indicate that the selection of proper construction systems and thermal insulation materials is important to the environmental performance of building retrofits, and these selections can lead to CO2 emission differences of up 16% in the region. The relative extrapolation results indicate significant environmental differences between urban morphologies. The LCA results show the potential strategic impacts of the inclusion of LCA methods in retrofit policies at the urban scale.

Urban Building Energy Models (UBEMs) are useful instruments to know the energy consumption of building stocks at urban and national levels. UBEMs can be classified into different types and subtypes. The current detailed physics-based bottom-up UBEMs at a national scale play a crucial role in assessing the energy efficiency of national building stocks and defining improvement strategies. These models heavily rely on archetypes and energy simulations, demanding significant computational resources. We propose here a new type of national-scale detailed physics-based UBEM based on Energy Performance Certificates (EPCs), and other open big data, which has the advantage that it can be automatically updated, in a short time, and with standard computer means. In this paper, we define the methodology to build this new type of national-scale EPC-based UBEM. We have checked that the model for the case of Spain can be automatically generated and updated in less than 6 h with a standard computer, and it generates results that match official data in more than 98 % for four indicators. The generated model contains information about 10,939,801 buildings in Spain, out of which 1,202,708 have EPCs. The model allows us to map and analyse the buildings in the country by integrating multiple variables of different nature, such as geographical (Autonomous Community, municipality, type of municipality), physical (area, number of floors, date of construction), use-related (main use of the building and use of each of its building units), and energy-related (climate zone, energy class, energy consumption, CO2 emissions). In this paper, we have proven that the model allows for the development of some indicators to measure the progress of decarbonisation trajectories whose development will become mandatory for European Member States soon.