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The article presents an analysis of changes in energy efficiency of new office buildings designed and constructed during the implementation period of the Energy Performance of Buildings Directive (2014–2024). Common criteria on energy efficiency were collected from Energy Performance Certificates (EPCs) and processed. The changes in final and primary energy for space heating, cooling and hot water production of certified office buildings were determined, and the improvements in buildings, their energy systems and energy sources were analysed. It was determined that buildings of Class C, designed between 2006 and 2017, showed an average thermal energy consumption for heating of 61, for cooling of 13 and for hot water production of 30 kWh/(m2·year), while buildings of Class A++, designed after 2020, consumed, respectively, 6, 9 and 17 kWh/(m2·year). The main reasons for these changes in energy consumption are the significant improvement of thermal insulation, increase of renewable energy in the heat supplied by district heating, the use of heat pumps for cooling, more efficient hot water boilers and optimized and insulated distribution pipelines. Even better results were hindered by the increased area of glazing, insufficient use of solar protection, users' preference for buildings of complex shape, and technically complicated electricity production. The results revealed that EPCs are an appropriate database for the analysis of changes in energy efficiency of buildings and for setting tasks for further improvement. [ABSTRACT FROM AUTHOR]

Residential buildings contribute 30% of the UK's total final energy consumption. However, with less than one percent of its housing stock being replaced annually, retrofitting existing homes has significant importance in meeting energy-efficiency targets. Consequently, many physics-based and data-driven models and tools have been developed to analyse the effects of retrofit strategies from various points of view. This paper aims to develop a data-driven AI model that predicts buildings' energy performance based on their features under various retrofit scenarios. In this context, four different machine learning models were developed based on the EPC (Energy Performance Certificate) dataset for residential buildings and standard assessment procedure (SAP) guidelines in the UK. Additionally, an interface was designed that enables users to analyse the effect of different retrofit strategies on a building's energy performance using the developed AI models. The results of this study revealed the artificial neural network as the most accurate predictive model, with a coefficient of determination (R2) of 0.82 and a mean percentage error of 11.9 percent. However, some conceptual irregularities were observed across all the models when dealing with different retrofit scenarios. All summary, such tools can be further improved to offer a potential alternative or support to physics-based models, enhancing the efficiency of retrofitting processes in buildings. [ABSTRACT FROM AUTHOR]

The energy efficiency of existing buildings is a crucial factor in addressing energy consumption challenges in European countries, accounting for nearly 40% of the total energy usage. One such country is Cyprus, which faces significant challenges in transforming its existing building stock into energy-efficient and sustainable structures. To face this situation, extensive focus has been made by the government on the energy-efficient retrofit of non-residential public buildings erected before 2010, which lack any energy efficiency measures. This study examines the case of the Pano Polemidia Cultural Hall (PPCH), which represents the building stock of that period. Through the simulation of two scenarios, before and after the adoption of retrofit measures, the existing energy performance is initially evaluated and then the adoption of sustainable solutions, which improve substantially the energy efficiency and can be easily adopted from the relevant authorities, is explored. These retrofit measures include installation of HVAC system, covering of the shell of the building with external thermal insulation, lighting replacement with LED devices, installation of PV system and solar panels, and replacement of the external openings with aluminum windows. The results derived show that the energy consumption of the building was reduced from 468 to 218 kWh/m2·yr, with renewable energy sources (RESs) contributing 177 kWh/m2·yr, the CO2 emissions were reduced from 136.73 to 11.5 kg/m2·yr, while the reduction in energy consumption per sector ranged from 25% in lighting to 83% in hot water. Therefore, it is evident that a comprehensive retrofitting plan can transform the PPCH into a near-zero energy consumption building that also provides value to the local community and can act as a successful example for any other non-residential buildings with similar characteristics. [ABSTRACT FROM AUTHOR]

The article presents an analysis of changes in energy efficiency of new office buildings designed and constructed during the implementation period of the Energy Performance of Buildings Directive (2014–2024). Common criteria on energy efficiency were collected from Energy Performance Certificates (EPCs) and processed. The changes in final and primary energy for space heating, cooling and hot water production of certified office buildings were determined, and the improvements in buildings, their energy systems and energy sources were analysed. It was determined that buildings of Class C, designed between 2006 and 2017, showed an average thermal energy consumption for heating of 61, for cooling of 13 and for hot water production of 30 kWh/(m2·year), while buildings of Class A++, designed after 2020, consumed, respectively, 6, 9 and 17 kWh/(m2·year). The main reasons for these changes in energy consumption are the significant improvement of thermal insulation, increase of renewable energy in the heat supplied by district heating, the use of heat pumps for cooling, more efficient hot water boilers and optimized and insulated distribution pipelines. Even better results were hindered by the increased area of glazing, insufficient use of solar protection, users’ preference for buildings of complex shape, and technically complicated electricity production. The results revealed that EPCs are an appropriate database for the analysis of changes in energy efficiency of buildings and for setting tasks for further improvement.

The energy efficiency of existing buildings is a crucial factor in addressing energy consumption challenges in European countries, accounting for nearly 40% of the total energy usage. One such country is Cyprus, which faces significant challenges in transforming its existing building stock into energy-efficient and sustainable structures. To face this situation, extensive focus has been made by the government on the energy-efficient retrofit of non-residential public buildings erected before 2010, which lack any energy efficiency measures. This study examines the case of the Pano Polemidia Cultural Hall (PPCH), which represents the building stock of that period. Through the simulation of two scenarios, before and after the adoption of retrofit measures, the existing energy performance is initially evaluated and then the adoption of sustainable solutions, which improve substantially the energy efficiency and can be easily adopted from the relevant authorities, is explored. These retrofit measures include installation of HVAC system, covering of the shell of the building with external thermal insulation, lighting replacement with LED devices, installation of PV system and solar panels, and replacement of the external openings with aluminum windows. The results derived show that the energy consumption of the building was reduced from 468 to 218 kWh/m2·yr, with renewable energy sources (RESs) contributing 177 kWh/m2·yr, the CO2 emissions were reduced from 136.73 to 11.5 kg/m2·yr, while the reduction in energy consumption per sector ranged from 25% in lighting to 83% in hot water. Therefore, it is evident that a comprehensive retrofitting plan can transform the PPCH into a near-zero energy consumption building that also provides value to the local community and can act as a successful example for any other non-residential buildings with similar characteristics.

The study is part of humanity's current concerns of tempering climate change for sustainable development, in the context where the construction sector is responsible for a significant percentage of greenhouse gas emissions. In the present work, through a rigorous documentation, the authors synthesize several existing green and sustainable building certification systems. Extending the study from buildings to green neighbourhoods, to university campuses and even to green cities, models of their sustainable development are highlighted. The authors summarize the results of the various "green" ratings, initiating "Top 10 Greenest Universities in the world", demonstrating the interest of certification and classification. The paper presents the case study of the University of Oradea. From this perspective, participation in a rating of green campuses, as well as certification of buildings, are stimulating elements for approaching a sustainable development strategy. Thus, with the registration in the UI GreenMetric World University Rankings, the University of Oradea is set to rise in the ranking, which actually led to the improvement of the green criteria and implicitly to an orientation towards a sustainable development of the university campus. At the same time, the paper demonstrates that the energy certification of old buildings engaged in the "wave of renovations" is a tool for the sustainable development of university campuses. [ABSTRACT FROM AUTHOR]

Measures on increasing energy efficiency is a way for ensuring sustainable energy supply, reducing emission of gases causing the greenhouse effect, improving safety of energy supply, decreasing dependence on import of energy and promoting the EU competitiveness. Improvement of energy performance of buildings as a direction of activities is provided in national policy planning documents of major importance such as the National Energy and Climate Plan for 2021–2030 and the Strategy of Latvia for the Achievement of Climate Neutrality by 2050. Residential buildings form a considerable part of the total Latvian housing stock – 27 % according to the number of buildings and 44 % according to their area. Therefore, the increase of energy performance of residential buildings is very significant for achieving the national energy saving targets, i.e. a cumulative savings of final energy consumption of about 6 PJ by 2030. The research analyses the sector of residential buildings, their statistical data, the energy consumption and requirements of the energy performance standards. To characterise this sector more comprehensively, information has been evaluated on energy performance certificates of residential buildings issued during the period from 2016 to 2021, allowing the authors to make general conclusions on the energy performance level of residential buildings and to provide proposals for increasing their energy efficiency. [ABSTRACT FROM AUTHOR]

As per general provisions of European Directive 2010/31/EU on the energy efficiency of buildings (recast), the Lithuanian government transposed the Directive into Lithuanian national law. In the process, the Lithuanian government prepared strategic documents in the field of energy performance and renewable energy that were integrated together through the National Energy and Climate Plan for 2021–2030 (NECP). To better understand the current situation vis-à-vis energy performance, the main characteristics of buildings pertaining to the Lithuanian multi-apartment building stock, classified according to their energy performance class, are analysed and discussed in this paper. Through the exploitation of data from the national Energy Performance Certificate (EPC) register, an overview of the energy performance of the existing Lithuanian residential building stock is presented along with an analysis of the unused potential energy savings pertinent to this building category. The results obtained from the analysed data of energy consumption in buildings shows that the policies adopted over the years were successful in improving the building stock, promoting the move towards the specifications required by a Class A++ (nearly zero energy buildings—NZEB) by 2021. The results show that this was primarily achieved by a significant reduction in the thermal energy used for space heating. [ABSTRACT FROM AUTHOR]

Increase of energy efficiency is Latvia's national priority and policy instrument that allows reducing consumption of energy and costs, increasing the safety level of energy supply and reducing dependence on import. One of the trends for reducing energy consumption is to increase energy performance of buildings. In compliance with the EU and Latvian political statements, it is required to promote renovation of residential and non-residential buildings. Studies regarding energy performance aspects in the sector of non-residential buildings in Latvia are comparatively rare; however, non-residential buildings form a considerable part of the building stock, and the increase of their energy performance can bring a significant contribution in achieving the national targets. The research analyses the sector of non-residential buildings, their characteristic statistical data, energy consumption and requirements of energy performance standards. To characterise this sector more comprehensively, information on energy performance certificates of buildings issued during the period from 2016 to 2021 has been evaluated, allowing to make general conclusions on the energy performance level of different non-residential buildings and provide proposals for trends to increase their energy efficiency. [ABSTRACT FROM AUTHOR]

Summary: The improvement of the energy performance of buildings is identified as one of the core challenges toward achieving a carbon‐neutral built environment. In the 2018 recast of the Energy Performance of Buildings Directive, the European Commission has emphasized the need for improved schemes, to ensure the best possible evaluation of the actual energy performance of buildings, taking into consideration all the parameters related both to their construction and operation. Significant research efforts have been designated in this area, to identifying the additional information required to not only improve the energy performance certification process but also to provide more thorough reports to end‐users. To increase comprehension, awareness, and thus genuine involvement, cutting‐edge digital technologies are expected to be used. The research project entitled "Next‐generation Dynamic Digital EPCs for Enhanced Quality and User Awareness" (D^2EPC GA 892984) introduces a comprehensive approach to next‐generation Energy Performance Certificates that addresses the main challenges and gaps in buildings' energy assessment process, by introducing additional layers of information for the assessor and the user. A non‐exhaustive list of the novel set of Energy Performance Certificates indicators, proposed in D^2EPC includes energy, smart readiness, wellbeing, comfort, financial, and sustainability related indicators. In this study, aspects of employing advanced digital solutions, like Building Information Modelling and Geographical Information Systems for the certification process are also demonstrated, through a well structured, high‐level, detailed representation of the next‐generation Energy Performance Certificates system architecture. This framework elaborates on individual components and their interaction, toward delivering the envisioned final enriched cloud‐based platform, that will enable dynamic Energy Performance Certificates based on (near) real‐time field data. This study aspires to initiate the discussion within the scientific community of buildings' energy assessment on the required practices for digitizing and enriching the certification process of buildings, in compliance with Industry 4.0 practices. [ABSTRACT FROM AUTHOR]

Shifting from heating using fossil fuel combustion to electrified heating, dominated by heat pumps, is central to many countries' decarbonisation strategy. The consequent increase in electricity demand, combined with that from electric vehicles, and the shift from non-renewable to renewable generation requires increased demand flexibility to support system operation. Demand side response through interrupting heating during peak demands has been widely proposed and simulation modelling has been used to determine the technical potential. This paper proposes an empirical approach to quantifying a building's potential to operate flexibly, presenting a metric based on measured temperature drop in a dwelling under standard conditions after heating is switched off, using smart meter and internal temperature data. A result was derived for 96% of 193 homes within a test dataset, mean temperature drop of 1.5 °C in 3 h at 15 °C inside-outside temperature differential. An empirical flexibility metric may support decision making and decarbonisation. For households it may support the transition to heat pumps, enabling time of use costs and tariffs to be better understood and system to be specified by installers. Electricity system stakeholders, such as aggregators and DNOs may use it to identify the potential for demand response, managing local networks, infrastructure and aggregation. [ABSTRACT FROM AUTHOR]

Today, energy consumption in the cities is dramatically increasing due to the growing population and various economic activities. The construction sector has a significant responsibility to increase global final energy consumption and total CO2 emission in the European Union. In the last two decades, policies on energy efficiency for residential buildings have been implemented in European Union. In this context, several legal regulations have been introduced in Turkey by the impact of the EU Directive on Energy Efficiency. Energy consumption and greenhouse gas emissions of structures are expected to be reduced with the Energy Performance Certificate (EPC) procedure described in the Regulation on Building Energy Performance. EPC actions should not be considered only in terms of the scale of a single building, and these efforts should be addressed with a holistic approach within the scope of land management. The data obtained from EPC applications should be integrated with land tenure, land use, topographic and atmospheric data to create an effective energy efficiency policy in settlements. Information infrastructure should be established to enable the application of spatial analysis. In this study, EPC actions in our country were evaluated within the land management paradigm, significant deficiencies were introduced, and some suggestions were made. [ABSTRACT FROM AUTHOR]

In the USA and the European Union, buildings account for more than 40% of total energy use and a large proportion of buildings are energy inefficient. Countries address these inefficiency challenges with various initiatives and strategies. One of them relies on rating buildings with energy performance certificates, with the goal that awareness on energy consumption would lead to an efficient retrofit. In this article, we analyze the different methods chosen by the USA and France to rate multifamily buildings, i.e., the Energy Star score and the Diagnostic de Performance Energétique. We conduct a case study of a multifamily housing using a Design of Experiments to determine what inputs are the most influent on the output. In the French certificate, the results show that the climate, ventilation system, and building envelope are the most influent inputs on the energy consumption. In the USA certificate, the actual energy consumption and the climate are the most influent factors on the building score. We then discuss the significant differences in the two approaches, and the consequences in terms of accuracy, as well as how the DPE and ES scores are used as a tool in public energy policy to propose energy conservation measures and reduce energy consumption. [ABSTRACT FROM AUTHOR]

The concept of a Digital Building Logbook (DBL) was first introduced with the European strategy 'Renovation Wave'. It is considered as one of two fundamental parts of which the Building Renovation Passport is composed: the DBL and a Renovation Roadmap. As the implementation of the DBL is a European priority, this paper reviews the existing literature and analyses the most developed European Digital Building Logbook models. The analysis includes iBRoad, ALDREN, X-tendo, and the Study on the Development of a European Union Framework for Buildings' Digital Logbook, from the perspective of seven key aspects: References used as a starting point for the model definition; Identification of the relevant stakeholders in the DBL; Identified potential user needs; Proposed structure of indicators; Data sources; Potential functionalities; and Operation and use. The results show that important advancement has been made, although there is still no consensus about crucial subjects, such as the indicators to be collected or how to collect and use them. This is probably due to the fact that the final functionalities (objective and scope) that the logbook should provide are not fully clear. [ABSTRACT FROM AUTHOR]

The government of Cyprus has developed packages addressing the energy performance of non-residential buildings, in order to achieve the national energy reduction objectives. Currently, Decree 366/2014 is in force, defining the requirements for a building to qualify as a nearly Zero Energy Building (nΖΕΒ). However, this falls short of addressing sufficiently the high cooling energy demand of buildings in Cyprus. This paper examines the energy and economic viability of various refurbishment scenarios by considering a public office building in the city of Limassol as a case study. The energy performance of the building was analysed first for its current state and also according to nZEB standards. In addition, a set of supplementary measures was examined, to develop a cost-effective alternative nZEB energy refurbishment model. Based on the results, the existing legislation, defining an nZEB is reconsidered prompting a proactive discussion towards the improvement of the current energy regulating Directives.

Worldwide, the building sector is responsible for consuming more than 36% of the final global energy and produces 39% of carbon dioxide emissions. Accordingly, sustainable retrofit is an important method to achieve energy reduction and sustainable development. However, the lack of information on retrofit technologies and their benefits trigger stakeholder’s opposition to retrofit actions. The Energy Performance Certificate tool can be used to overcome the knowledge gap and boost energy saving by strengthening its recommendation report with retrofit technologies for energy performance. Therefore, this paper attempts to determine the best retrofit technologies to be highlighted in the Energy Performance Certificate’s recommendation report by considering stakeholder’s opinions. For this purpose, a model based on Quality Function Deployment has been developed. The model analyzes the data regarding stakeholder’s expectations when deciding to retrofit, and the potential retrofit technologies used. To validate the applicability of the proposed model, a case study was conducted in Romania. The findings are expected to contribute to improving the quality of the Energy Performance Certificate, as reflecting stakeholder’s opinions combined with sustainable concepts to achieve significant energy savings.

Energy performance certificate is one of the main legal instruments of energy efficiency policy with the objective to reduce energy consumption in buildings in order to meet requirements for the energy performance of buildings. Energy performance certificate shall include the energy performance of a building as well as recommendations for the cost-optimal or costeffective enhancements of the energy performance of a building or building unit. The rating scheme of energy performance certificate also plays a significant role within programmes such as New Green Savings.

Ireland’s Climate Action Plan aims upgrade 500,000 homes to B2 Energy Performance Certificate (EPC) standard by 2030. Evidence of an Energy Performance Gap, where actual energy use differs from the EPC, could undermine progress towards such targets. This paper studies the energy performance gap for a general housing sample (n = 9923) over multiple years. It provides a novel comparison between whole-home energy use (electricity and gas) that accounts for fuel switching and removes potential rebound effects by excluding households that may have changed their behaviour following a retrofit. Results suggest that actual energy use is unresponsive to the EPC, with a range of 457 kWh/year observed across EPC-level averages for the entire sample. This difference equated to less than 5% of the sample average annual energy use observed. The Energy Performance Gap range features an average deficit of 17% below theoretical energy use. The least energy efficient dwellings feature an average difference ranging from − 15 to − 56% of the relevant EPC. Conversely, energy efficient houses display higher-than-theoretical energy use, with average surpluses ranging from 39 to 54% of the relevant EPC. Results sound a note of caution for policymakers that rely on a theoretical EPC to deliver real energy savings. Future EPCs could be improved by incorporating historical household energy usage to help improve models. [ABSTRACT FROM AUTHOR]

This study analysed renovation measures implemented with ARA renovation subsidy in Finland in multifamily apartment buildings. Measured energy data was used to calibrate the energy simulation model of the most typical renovated building from the 1970 s. For the reference building, a comprehensive set of renovation packages were applied to assess the performance of ARA grants. It was noticed that official energy performance certificates (EPC) overestimated before the renovation energy use as well as energy saving by a factor of almost 2. It was notable that in calculated EPCs, after renovation, EP-value was higher than before renovation, EP-value based on measured energy use. The main reasons for faulty energy calculations were strong overestimations in the building leakage rate and ventilation airflow rate. Renovation packages reduced EP-value by 8 % to 27 %, including lighting and appliances. Those using district heat resulted in a small increase in electricity with a flat duration curve, but the combined ground source and exhaust air heat pump showed the highest peak electricity power increase by factor 6. Exhaust air heat pump, window replacement and photovoltaic were the most cost-effective options, while packages with additional insulation faced considerably higher costs than the sum of ARA support and monthly savings could cover bank loans; thus, ARA support was clearly too small to support deep renovation. The need to improve the accuracy of EPCs in assessing energy performance to facilitate more effective financial support was a finding that can be important for any support scheme to secure the necessary funding for renovation. [ABSTRACT FROM AUTHOR]

This research compares domestic metered energy data, for both gas and electricity consumption, against characteristics drawn from a building stock model of Greater London, UK. The energy analyses are limited to houses (single-building, single household) with one standard electricity meter and one mains gas meter as the principal subset. This provides a sample of almost 1.2 million, or 75%, of London’s stock of houses. Energy use was normalised by calculated floor area, providing an energy use intensity (EUI; kWh/m2/yr), which allows properties of all sizes to be compared. Examination of EUIs of each built form versus Energy Performance Certificate (EPC) current energy efficiency (Asset Rating value) indicates weak, or very weak, correlation between the two, particularly for electricity. Practice relevance The study demonstrates how a detailed building stock model may be used for the analysis of metered energy use in the buildings of urban areas: in this case houses. The analyses examine some aspects of the data that constitute the stock model, such as built form and age, which are held at the scale of what can be considered to be individual buildings. The model currently covers Greater London, but is being built for other urban areas of England and Wales, thus giving it the potential to aid different layers of government or other actors in their efforts to reduce energy use in the building stock—both domestic and non-domestic. Some aspects of the model, such as the calculation of floor areas, should be replicable, where these data are accessible.

Recent studies have sought to explore the relationship between environmental and financial performance, in particular the relationship between the energy efficiency level of a building and its financial value. The present real estate dataset contains 43 variables of repeat sales transactions, energy performance certificate (EPC) rating, index of multiple deprivation (IMD), and geographical location of properties in England and Wales involved in a total of 4,201 transactions from 1995 to 2012. This dataset enables researchers and practitioners to further explore important questions regarding the nexus between the real estate industry, sustainability levels, and socio-economic aspects. Due to the scarcity of publicly available quality real estate data, the dataset detailed in this article may play a relevant role by becoming easily discoverable, clearly explained, and structured to be ready to be used by researchers, analysts, and policymakers. The empirical analysis of the economic case for energy-efficient dwellings in the UK private rental market performed in Fuerst, et al. [1] is based on this dataset.

The concept of a Digital Building Logbook (DBL) was first introduced with the European strategy ‘Renovation Wave’. It is considered as one of two fundamental parts of which the Building Renovation Passport is composed: the DBL and a Renovation Roadmap. As the implementation of the DBL is a European priority, this paper reviews the existing literature and analyses the most developed European Digital Building Logbook models. The analysis includes iBRoad, ALDREN, X-tendo, and the Study on the Development of a European Union Framework for Buildings’ Digital Logbook, from the perspective of seven key aspects: References used as a starting point for the model definition; Identification of the relevant stakeholders in the DBL; Identified potential user needs; Proposed structure of indicators; Data sources; Potential functionalities; and Operation and use. The results show that important advancement has been made, although there is still no consensus about crucial subjects, such as the indicators to be collected or how to collect and use them. This is probably due to the fact that the final functionalities (objective and scope) that the logbook should provide are not fully clear.

This research compares domestic metered energy data, for both gas and electricity consumption, against characteristics drawn from a building stock model of Greater London, UK. The energy analyses are limited to houses (single-building, single household) with one standard electricity meter and one mains gas meter as the principal subset. This provides a sample of almost 1.2 million, or 75%, of London's stock of houses. Energy use was normalised by calculated floor area, providing an energy use intensity (EUI; kWh/m2/yr), which allows properties of all sizes to be compared. Examination of EUIs of each built form versus Energy Performance Certificate (EPC) current energy efficiency (Asset Rating value) indicates weak, or very weak, correlation between the two, particularly for electricity. [ABSTRACT FROM AUTHOR]

Energy performance certificates (EPCs) are ratings of domestic building energy performance mandated across the European Union. Their aim is to provide a reliable assessment of a building’s energy performance whilst accounting for non-building effects such as weather and occupancy. Current rating methods, based on theoretical calculations, can introduce significant error from an inability to estimate real building performance. Other methods using real energy data cannot isolate building performance from other effects due to low data resolution. The installation of smart meters in large proportions of the housing stock in European Union member states presents an opportunity. Harnessing high-resolution energy data can create or inform building energy performance ratings with reduced error and at scale. This critical review explores the challenges and opportunities of using smart meter data in building energy ratings, focusing primarily on quantifying the thermal performance of the building and heating system. The research gaps in this emerging field are identified, including: demonstrating that the rating is truly independent of the behaviour of specific occupants; the additional data inputs that add most value in combination with smart meter data; and reducing uncertainty whilst limiting the complexity of the measurement and calculation. 'Practice Relevance' Increasing evidence shows current EPCs are unreliable. This unreliability can affect their usefulness to householders and the provision of evidence for policy decisions. The incorporation of metrics constructed from smart meter data can provide a rating of building thermal performance that better reflects the actual performance of a dwelling. The potential advantages of incorporating smart meter data would improve the reliability of building energy ratings and quantify the rating uncertainty on a per dwelling basis, which would be useful for risk assessment to inform finance and retrofit decisions. Technical challenges are identified and explained for the inclusion of smart meter data. These are summarised as follows: ensuring that ratings remain independent of occupant behaviours/practices; and identifying which additional data inputs increase reliability and enable more informed retrofit decision-making whilst keeping the rating cost low and the calculation complexity tractable.

Energy-poverty (EP) must be considered an energy-related issue since buildings are a central part of people’s daily lives. Thus, it has an important role in energy-related policy implementation. Even though the European Union (EU) has endorsed general energy efficiency through the Energy Efficiency Directive and Energy Performance of Buildings Directive recast, it was the Clean Energy Package for all Europeans that clearly highlighted EP. The growing concerns with EP have also been emphasised in subsequent directives and initiatives. Despite some regulatory framework and the milder climate situation, the proportion of the population experiencing thermal discomfort in southern and eastern European countries, namely in the winter season, is relatively high, reflecting the poor thermal performance of building stock, low family incomes and high energy prices, among others. The current work analysed the EP evolution in Portugal in the EU context, and the Thermal Building Regulations and Energy Efficiency Policies developed, aiming to add insight into the effectiveness of those policies concerning EP mitigation in Portugal as an EU Member state. Moreover, a critical debate on the potential to lower the EP Portuguese situation was also an objective to pursue. It is plausible to admit that reducing EP by acting on residential building stock, namely through the increase of energy efficiency and comfort, plays a key role in improving the living conditions, namely of vulnerable households and deprived areas. This will also decrease energy consumption and dependence while further promoting a smarter, sustainable and inclusive society, contributing to economic growth.

The government of Cyprus has developed packages addressing the energy performance of non-residential buildings, in order to achieve the national energy reduction objectives. Currently, Decree 366/2014 is in force, defining the requirements for a building to qualify as a nearly Zero Energy Building (nΖΕΒ). However, this falls short of addressing sufficiently the high cooling energy demand of buildings in Cyprus. This paper examines the energy and economic viability of various refurbishment scenarios by considering a public office building in the city of Limassol as a case study. The energy performance of the building was analysed first for its current state and also according to nZEB standards. In addition, a set of supplementary measures was examined, to develop a cost-effective alternative nZEB energy refurbishment model. Based on the results, the existing legislation, defining an nZEB is reconsidered prompting a proactive discussion towards the improvement of the current energy regulating Directives. [ABSTRACT FROM AUTHOR]

The member states of the European Union must increase the energy efficiency in residential buildings within the plan to reduce the external energy dependence and energy shortage. In the present work, a standard building representative of the existing buildings in Spain built before 1980 was used. An evaluation of the energy rating of that building in each climatic zone of Spain was carried out to assess the influence of these climatic conditions on energy consumption and greenhouse gas emissions. This analysis was carried out with Cerma software according to the calculation procedure demanded by the Spanish Building Technical Code. Results show that E or F energy score was obtained for the different climatic zones and with significant differences in CO2 emissions, even for climatic zones with the same energy rating. A sensitivity study of the necessary enhancements in each climatic zone was carried out to analyze the influence of most common energy demand and thermal system improvements, and combinations of them. Also, the minimum requirements to obtain D qualification in each Spanish climatic zone were obtained. As a result, it is possible to reduce emissions in Spain by over 3.5 Mt CO2 per year. In climatic zones with initial qualification E, it is possible to reach a D label, avoiding 40% of the initial CO2 emissions and reducing primary energy consumption to about 50 kWh/m2 year (over 60% reduction). For the climatic zones with initial qualification F, over 53% of the initial CO2 emissions are avoided by reaching D label. Zones with the highest heating demand (over 230 kWh/m2 year) and very low cooling demand need to improve thermal systems by means of a heat pump. Finally, some policy measures to create lines of financial aids or subsidies for the implementation of actions to reduce energy demand in Spanish homes are proposed. [ABSTRACT FROM AUTHOR]

Energy performance certificate is one of the main legal instruments of energy efficiency policy with the objective to reduce energy consumption in buildings in order to meet requirements for the energy performance of buildings. Energy performance certificate shall include the energy performance of a building as well as recommendations for the cost-optimal or costeffective enhancements of the energy performance of a building or building unit. The rating scheme of energy performance certificate also plays a significant role within programmes such as New Green Savings. [ABSTRACT FROM AUTHOR]

As the urban population continues to expand and is expected to comprise 80% of the total population in 2050, it is crucial to ensure the sustainability and energy efficiency of cities. Among all the homes globally, Hard-to-Decarbonize (HtD) buildings are estimated to be a quarter of them. Identifying the HtD houses and proposing strategies for these houses is important to reach the global net zero target. However, the study of HtD houses has historically been neglected. Previous studies mainly focus on simulating, predicting and understanding attributes that are directly related to energy usage and efficiency. In this research, a methodology for identifying HtD buildings with publicly available data is proposed and tested in Cambridge, UK. A dataset of HtD houses in Cambridge is organized, with criteria derived from the Energy Performance Certificate (EPC), which results from detailed inspections of houses. Street view images (SVI), aeriel view images (AVI), land surface temperature (LST), and building stock data are used together for the prediction with deep learning. The classification precision for HtD buildings is able to achieve 82%. This study also explores the minimal data needed for the high-accuracy prediction of HtD houses. Results show that SVI contributes the most to the prediction. • A deep learning-based framework is proposed to Identify Hard-to-Decarbonize homes. • Datasets of HtD buildings are compiled from public data. • Contribution of different data sources are identified. [ABSTRACT FROM AUTHOR]

A building energy performance gap can be illustrated as the difference between the theoretical (methodologically defined) and the actual energy consumption. In EU countries, Energy Performance Certificates are issued when buildings are constructed, sold, or leased. This information is the first step in order to evaluate the energy performance of the building stock. In Serbia, when issuing an energy certificate, the adopted national methodology recognizes only energy consumption for heating. The main purpose of this paper is to evaluate the energy gap and estimate the relevance of an Energy Performance Certificate to meet the national energy efficiency or carbon target. An Energy Performance Certificate determines the theoretical residential and commercial building energy efficiency or its “design intent”. This research stresses the necessity of measuring and achieving reductions in actual energy consumption through system regulation and consumers’ self-awareness in buildings. The research compares the performance of the building stock (135) that is connected to the District Heating System (DHS), with its own integrated heat meter, to Individual Gas Boiler (IGB) systems (18), in the city of Novi Sad, Serbia, built after 2014. For the purpose of comparing energy consumption, 16 buildings were selected that are very similar in terms of design, operation, and location. The data used are derived from metered consumption data, official evidence of city service companies, and Energy Performance Certificates of the considered buildings. We have determined that IGB systems have a much wider specific annual performance gap (11.19–101 kWh/m2a) than the buildings in the DHS (3.16–18.58 kWh/m2a).

This article presents and discusses the challenges of refurbishing historic apartment buildings by correlating findings from research projects LEAF and CulClim. Our aim is to shed light on how residents can partake in and optimise the refurbishment process after energy performance certificates (EPC) have been conducted. The background is that historic apartment buildings are generally more complex than single family buildings with respect to the energy efficiency process as they often have multiple owners with different priorities. The case studies from Norway and Sweden have conceptually contrasting energy performance certificate (EPC) systems. Identified advantages and shortcomings concerning both systems are discussed. In Sweden, the restrained recommendation of measures can lead to national mitigation targets not being realised. In Norway, excessive and unqualified recommendations risk reducing the cultural heritage values of the existing building stock as well as having a negative environmental impact on greenhouse gas emissions. A bottom-up approach incorporating the resident's objectives is presented and discussed. Results suggest that improved EPC-systems and a broadened procedural approach to decision making will ease the process and improve the outcome of the refurbishment with respect to both energy and heritage aspects. [ABSTRACT FROM AUTHOR]

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In 2008, the Chartered Institution of Building Services Engineers (CIBSE TM46 UC) presented an annual-fixed thermal energy benchmark of 240 kWh/m2/yr for university campus (UC) buildings as an attempt to reduce energy consumption in public buildings. However, the CIBSE TM46 UC benchmark fails to consider the difference between energy demand in warm and cold months, as the thermal performance of buildings largely depends on the ambient temperature. This paper presents a new generation of monthly thermal energy benchmarks (MTEBs) using two computational methods including mixed-use model and converter model, which consider the variations of thermal demand throughout a year. MTEBs were generated using five basic variables, including mixed activities in the typical college buildings, university campus revised benchmark (UCrb), typical operation of heating systems, activities impact, and heating degree days. The results showed that MTEBs vary from 24 kWh/m2/yr in January to one and nearly zero kWh/m2/yr in June and July, respectively. Based on the detailed assessments, a typical college building was defined in terms of the percentage of its component activities. Compared with the 100% estimation error of the TM46 UC benchmark, the maximum 21% error of the developed methodologies is a significant achievement. The R-squared value of 99% confirms the reliability of the new generation of benchmarks.

Urban building energy models (UBEMs) are considered as applicable tools for urban energy planning. Model developers use different strategies to simulate urban building energy use appropriately, and yet they are often doing so in the absence of high-quality data. While data collection is challenging in many cases, in Sweden, the availability of national databases is relatively good and is expected to facilitate the modeling procedure considerably. This study aims to develop, calibrate and validate an UBEM using available national data, including GIS-based property maps and energy performance certificates (EPCs). The developed UBEM offers an automated framework for constructing simple building-level models from open data and conducting energy simulations in EnergyPlus. The developed UBEM was calibrated and validated for two case study cities in Sweden, Borlänge and Uppsala, where the mean absolute percentage error (MAPE) between simulated results and EPC data was 26% and 22%, respectively. Furthermore, a downward trend was observed in the MAPE with increasing spatial aggregation from building to district and city levels (from 26% to 21% and 10%), which highlights the performance of the UBEM in this study to support accurate urban-scale energy analyses for buildings. • An UBEM from open GIS and EPC data was developed. • Using EPC data, the UBEM was calibrated and validated. • The MAPE of the UBEM was 26% and 10% on the building level and city level. [ABSTRACT FROM AUTHOR]

Building databases are important assets when estimating and planning for national energy savings from energy retrofitting. However, databases often lack information on building characteristics needed to determine the feasibility of specific energy conservation measures. In this paper, machine learning methods are used to enrich the Swedish database of Energy Performance Certificates with building characteristics relevant for a chosen set of energy retrofitting packages. The study is limited to the Swedish multifamily building stock constructed between 1945 and 1975, as these buildings are facing refurbishment needs that advantageously can be combined with energy retrofitting. In total, 514 ocular observations were conducted in Google Street View of two building characteristics that were needed to determine the feasibility of the chosen energy retrofitting packages: (i) building type and (ii) suitability for additional façade insulation. Results showed that these building characteristics could be predicted with an accuracy of 88.9% and 72.5% respectively. It could be concluded that machine learning methods show promising potential to enrich building databases with building characteristics relevant for energy retrofitting, which in turn can improve estimations of national energy savings potential.

The paper reports a methodology developed to map energy consumption of the building stock at the urban scale on a GIS environment. Energy consumption has been investigated, focusing on the shift from the individual building scale to the district one with the purpose of identifying larger homogenous energy use areas for addressing policies and plans to improve the quality and the performance levels at the city scale. The urban planning zoning concept was extended to the energy issue to include the energy behavior of each zone that depends on the performance of its individual buildings. The methodology generates GIS maps providing a district scale visualization of energy consumption according to shared criteria. A case study in Bologna city (Italy) is provided. In the specific case, the last update of Emilia-Romagna regional urban planning regulation required a mapping action regarding energy efficiency of homogeneous urban portions defined by the General Urban Plan. The main achieved results are (a) a methodology to identify homogeneous areas for analyzing energy consumption; (b) an updated energy map of Bologna Municipality.

The Energy Performance Certificate (EPC) requirements in Europe have provided rich data of energy efficiency status of individual buildings at scale, allowing appropriate assessments to be carried out without the need of conducting additional surveys. By 2012, the EPC data in England and Wales in the UK has reached a coverage of up to 45% of the entire building stock (DECC 2014), and the number of new certificates added every year is over 1 million. The work presented here seeks to understand the potential of using such dataset to deliver systematic analysis of energy efficiency of buildings at a city scale. This study utilises all EPC datasets available for the city of Southampton, UK, and developed an automatic geographic-referencing methodology so the EPC data can be integrated onto geographic information systems (GIS). Such methodology allows large quantity of EPC data to be analysed spatially, facilitating the assessment of energy performance of different regions in a city. The results show clearly areas in the city that have the lowest or highest level of performance in terms of buildings’ energy efficiency, and revealed the impact of certain building intervention measures (such insulation, double glazing) on the energy consumption within the considered buildings. The analyses show that factors such as the existence of high streets and new building developments have significant influence on the energy efficiency in the city where these are present. The geographic-referencing methodology developed in this study has the potential to be utilised in a wide range of subjects, bridging the current gap of data availability, allowing building related datasets to be incorporated with GIS analysis.

Highlights • Two simplified optimization models for whole-building retrofit planning are proposed. • The models reduce the complexity of systematic building retrofit planning problems. • The models eliminate a costly detailed bottom-up energy audit process. • The models consider green building policy based on EPC and the tax incentive. • The models can be of great help for retrofit plans for a building portfolio. Abstract Determining a systematic whole-building retrofit plan for envelope components and indoor appliances to achieve targets such as cost savings and policy compliance is a challenging task. To be specific, the systematic whole-building retrofit problem, when solved by an optimization approach, is highly complicated. It is sometimes even impossible to find a solution with given computation resources and algorithms. In addition, a costly comprehensive bottom-up audit is required to establish the parameters of the problem. This study presents two models to reduce the complexity of the systematic whole-building retrofit optimization problem. Firstly, the proposed models use the grouping concept to optimize the retrofit of subsystems in a building instead of individual components/appliances, which reduces the dimension of the problem effectively. Secondly, the models use so-called ‘notch test’ data, which are sampled and verified savings of an intervention, to eliminate the need for bottom-up energy audits. This further simplifies the retrofit optimization problem and reduces the retrofit cost. The models are based on our previous work and aim at energy savings maximization and payback period minimization, considering the green building policy and tax incentive initiatives. A case study shows that about 2530 MWh energy savings and an A rating from the energy performance certificate standard can be obtained with a payback period of 59 months, which verifies the feasibility and effectiveness of the models proposed. [ABSTRACT FROM AUTHOR]