Search Results (58)

Improving residential energy efficiency is essential to meeting UK net-zero targets, yet retrofit uptake in the private rented sector (PRS) remains limited. While many studies examine retrofit measures or Energy Performance Certificates (EPCs), few integrate comparative technology performance, cost–benefit outcomes, and landlord–tenant perspectives within a single housing context. This paper addresses that gap through a mixed-methods case study of a professionally managed private rented housing portfolio in South London, assessing four retrofit technologies: photovoltaic (PV) panels, air source heat pumps (ASHPs), double glazing (DG), and insulation. Quantitative analysis showed that ASHPs delivered the greatest EPC improvement, with 54.5% of properties achieving a two-band uplift, while PV panels offered the strongest financial return, with an average payback period of 11.7 years. Houses achieved the strongest overall results, with combined PV + ASHP retrofits delivering the best technical and financial performance; however, this pairing was only feasible in houses because of the physical requirements for both roof space and external unit installation, whereas flats and maisonettes were more constrained by space and installation feasibility. Stakeholder analysis findings revealed knowledge and incentive gaps: many tenants overestimated the effectiveness of double glazing, while landlords identified high upfront costs and delivery challenges as key barriers. Wider PRS decarbonisation will therefore require stronger policy support, streamlined retrofit delivery, and improved tenant awareness. Full article

The environmental performance of residential buildings depends not only on envelope quality but also on the choice of heating, domestic hot water, and ventilation systems. This study presents a comparative assessment of eight technology packages for a reference single-family house located in Warsaw, Poland, using a harmonised framework under Polish EPC calculation assumptions, with identical building parameters, system boundaries, and functional assumptions for all variants. Operational performance was evaluated using Energy Performance Certificate indicators, including useful energy, final energy, non-renewable primary energy, operational CO₂ emissions, and the share of renewable energy sources. In addition, a comparative 50-year scenario of operational CO₂ emissions was developed, and a screening life-cycle carbon assessment of the reference building fabric and major building components was performed to provide a material and construction-related carbon context for the operational comparison. The embodied impacts of package-specific technical systems were excluded from the LCA scope. The results showed that fossil-dominated packages generated the highest primary energy demand and operational emissions, whereas renewable-supported and hybrid configurations substantially improved environmental performance. Under the adopted EPC-based accounting assumptions, the fully renewable packages achieved the lowest operational indicators; however, these variants should be interpreted as upper-bound theoretical scenarios rather than as demonstrated real-life zero-emission solutions. Therefore, they were not used as the main basis for the practical ranking. Among the practically comparable mixed configurations, the most favourable operational results were obtained for renewable-supported heat-pump-based packages. The screening life-cycle assessment indicated that a substantial part of the total environmental burden was associated with the product and construction stages of the reference building. The results confirm that the interpretation of residential technical packages depends strongly on the adopted assessment perspective and that operational indicators should be considered together with at least a screening-level carbon context for the building fabric. According to the calculation results, the EP value ranges from 0 to 90.8 kWh/(m²·year), depending on the technology package. Full article

Long-term energy sustainability in the built environment depends not only on deploying renewables but also on maintaining high energy efficiency that consistently lowers demand and enables more effective use of low-carbon electricity over time. This paper presents an illustrative case study that demonstrates a low-data, EPC/audit-based screening workflow for assessing operational energy, carbon, and water-related indicators in a non-residential building. An explanatory case study is conducted for a mixed-use logistics facility in Poland (≈610 m²), combining approaches to useful/final/primary energy indicators with operational carbon and water footprints. The operational water footprint is evaluated as a screening metric (L/kWh) applied to the annual electricity balance and tested across PV self-consumption levels (25/50/75%) to reflect the role of energy management and flexibility. The results indicate that an efficiency-oriented modernization pathway supported by PV integration (≈64 kWp; ~57,350 kWh/yr) reduces the primary energy performance indicator EP from 154 to 62.5 kWh/m²·yr, corresponding to a 59% reduction in annual primary energy demand. The operational water footprint indicator decreases nearly linearly with increasing PV self-consumption, demonstrating that long-term benefits depend on sustained efficiency and on maximizing on-site renewable utilization through controls, demand shifting, and/or storage. Overall, the framework supports transparent benchmarking and the development of staged pathways for integrating renewable and low-carbon energy systems into logistics-building portfolios, while maintaining an analytical focus on operational energy, carbon, and water performances. Full article

Energy performance certification of buildings is a key instrument for assessing energy efficiency within the framework of the Energy Performance of Buildings Directive (EPBD). In practice, significant discrepancies are often observed between the predicted and actual energy performance of buildings. One of the main causes of this discrepancy is non-compliance with technological procedures during construction. This paper analyses the energy and economic consequences of such deviations through a case study of a newly constructed residential building in northern Slovakia that was originally certified in the A0 energy class. The research methodology included in situ inspection of the building, thermographic measurements, destructive probes of the building envelope, analysis of project documentation, and recalculation of energy performance using measured building parameters. The results revealed significant deficiencies in the thermal insulation of the building envelope, roof construction, and window airtightness. After recalculation based on measured parameters, the building’s energy classification deteriorated from A0 to B. The total energy demand increased by 46%, while primary energy demand increased by 141%. The results demonstrate that construction deviations can significantly affect the reliability of energy performance certification. The study highlights the importance of verifying the actual condition of buildings during construction to ensure the reliability of EPC assessments. Full article

This paper presents a comprehensive economic comparison between renewable and fossil-fuel-based heating systems for a newly constructed residential building in Kraków, Poland, over the period 2022–2030. The analysis introduces the concept of Corrected Final Energy Consumption (CFEC) as a harmonized measure for comparing various energy sources and applies the Present Value of Total Lifecycle Cost (PVTLC) as an appropriate financial metric for non-commercial residential investments. Four heating options were examined: district heating system (DHS), gas boiler, air-to-water heat pump, and heat pump combined with photovoltaic (PV) panels. Based on real tariffs and standardized data from the Energy Performance Certificate (EPC), the DHS option demonstrated the lowest lifecycle cost, while the air-to-water heat pump—despite environmental advantages—proved the most expensive without substantial subsidies. Sensitivity analyses confirmed the strong influence of investment subsidies and fuel price fluctuations on the competitiveness of alternative systems. The findings highlight the methodological shortcomings of conventional annual-cost approaches and propose PVTLC as a more reliable decision-making tool for residential energy planning. The study also discusses regulatory, climatic, and behavioral factors affecting investment outcomes and emphasizes the need to integrate financial, environmental, and social criteria when evaluating household-level energy solutions. Full article

In response to the pressing need to increase energy efficiency in buildings, new regulations are continually being introduced to enforce higher standards. The recent recast of the Energy Performance of Buildings Directive (EPBD IV) emphasizes the establishment of national performance standards, which will supposedly be based on the national Energy Performance Certificate (EPC). However, energy certifications across several European countries rely on a quasi-steady state approach, which fails to accurately represent real-performance conditions due to inherent limitations. This is more evident in buildings located in warm climates, where actual energy demands far exceed those predicted by energy certifications. To address these discrepancies, a shift towards dynamic performance assessment methods is pivotal. This research compares the heating and cooling energy demand of an office building using two approaches: the quasi-steady state, prescribed by the Italian standard, and the dynamic state. After calibrating the dynamic model, it was employed to perform a simulation incorporating more detailed user profiles and boundary conditions than those used in the quasi-steady state method. This approach allows the preservation of both reasonable accuracy and practical applicability. Finally, a sensitivity analysis of influential parameters seeks to elucidate the main causes of divergence between simulated and measured performance and to identify opportunities for improving EPC. The simulation outcomes indicate that, while the stationary model yields heating energy demand relatively aligned with the measured data, it shows substantial discrepancies (about 50%) in the cooling predictions. Moreover, the findings reinforce the inadequacy of the simpler approach and advocate for the integration of dynamic state simulation in energy performance assessment, aligning with the objectives of the recent EPBD. Full article

As climate policy and energy costs increasingly influence housing markets, understanding how energy efficiency is capitalized into home prices has become a critical question for both researchers and policymakers. While prior studies confirm the existence of a green premium—the price advantage of more energy-efficient homes—less is known about how this premium evolves over time in response to shifting regulations, awareness, and market conditions. This study provides new empirical evidence on the dynamic valuation of energy efficiency in the London housing market between 2013 and 2021. Using a repeat-sales framework, we isolate within-property price changes and examine how energy performance is capitalized over time. We find that the green premium associated with higher current energy efficiency strengthened steadily, rising from statistically insignificant levels in 2013 to approximately 0.47% per Energy Performance Certificate (EPC) point by 2021. Meanwhile, the price penalty for a large efficiency gap, reflecting unrealized upgrade potential, narrowed substantially in 2020 and 2021, indicating a marked reduction in buyers’ aversion to less efficient homes. This study adds a new dimension to the green premium literature. It provides empirical evidence that the relationship between energy efficiency and housing value is not static, but responsive to regulatory, economic, and social changes. By tracking year-by-year changes in London, our analysis offers insight into how quickly market preferences adjust and how interventions like minimum efficiency standards translate into property values. This enriched understanding moves the field beyond the question of whether a green premium exists, to how and why it evolves. Full article

Historic buildings are often assumed to have poor energy performance, and energy optimization of the buildings is perceived as threatening their cultural values. This study tests these assumptions. First, it examines the energy performance of Danish historic apartment buildings (buildings constructed before 1950 with a high preservation value, according to the national SAVE system (Survey of Architectural Values in the Built Environment)). Second, it assesses the extent to which the energy improvements in the historic buildings conflict with their historic value. An analysis of energy performance certificates (EPC) in 13,000 Danish historic apartment buildings reveals that they perform no differently than apartment buildings with a low preservation value, with 46% of historic apartment buildings achieving an EPC rating of “C”. Nevertheless, significant potential for further energy improvements is identified. Expert interviews and three case studies indicate that typical interventions for enhancing buildings’ energy performance rarely interfere with its historic values. This is partly due to structural conditions where shoulder-by-shoulder location, high building compactness, and supply with district heating gives a beneficial foundation for a high energy performance. Potential conflicts between energy improvements and historic values exist but are often resolved through dialogue between local authorities and owners about the interventions. Full article

Residential heritage buildings (RHBs) are facing complex conservation challenges due to national policies aimed at achieving carbon emission reductions and associated retrofit recommendations. This long-term study (2007–ongoing) focuses on how such nationwide policies, particularly energy performance certificates (EPCs) and minimum energy efficiency standards (MEES), affect a cluster of 12 RHBs on the National Trust’s Wallington Estate in Northumberland, England. Data were collected using a combination of building measurements and survey observations, alongside assessment of tenant behaviours through an interview process. The research findings revealed a 53% average improvement in EPC ratings following a retrofit. However, the tenant interviews exposed some key limitations in current policy tools, including their failure to reflect actual energy use and behavioural patterns. For instance, despite improved EPC scores, some tenants reported high fuel costs and continued to experience heat loss and dampness in the RHBs. These novel findings of this longitudinal study challenge the suitability of current retrofit metrics and advocate for a people-centric and context-specific approach to energy efficiency in heritage buildings. They also highlight the drawback of proposed minimum EPC ‘C’ standards within the UK’s existing housing stock, particularly in relation to idiosyncratic RHBs. Full article

Conventional methods of studying houses’ Energy Performance Certificates (EPCs) typically fail to investigate the impact of interrelated contextual elements instead fixating exclusively on the specific attributes of individual houses. This study presents a new method that combines network graph analytics (NGA) with interactive visual analytics to investigate hidden linkages at the individual house level. Our proposed platform collects and analyses data related to housing attributes, creates a network based on the links between these attributes, and employs sophisticated graph algorithms to provide visual representations. Users have the ability to dynamically choose postcodes, metrics, and attributes, which, in turn, generate layouts of networks that provide valuable insights. The visualisation utilises colour gradients and node metrics to improve the comprehensibility of energy performance areas. The platform enables homeowners and stakeholders to comprehend the interrelationships between aspects such as neighbouring housing features, and house infrastructure. The results prove the efficacy of the strategy by giving a collection of case studies that encompass various Energy Performance Certificates (EPCs) ranging from A to G. Each case study demonstrates the evolution of network architectures and visual assessments, showcasing the energy performance linked to certain EPC ratings. The platform offers a user-friendly interface for stakeholders to investigate and understand attribute relationships. Full article

This research presents a multi-scale framework designed for assessing the energy performance and climate vulnerability of three existing residential buildings in a small Central Italian municipality. By integrating dynamic energy simulations with high-resolution climate projections, the study investigated how the selected building typologies responded to changing environmental conditions. Validation against Energy Performance Certificates (EPCs) confirmed the framework’s robustness in accurately capturing energy consumption patterns and assessing retrofit potential. The results revealed a general reduction in heating demand accompanied by an increase in cooling requirements under future climate scenarios, with notable differences across building types. The reinforced concrete building showed greater sensitivity to rising temperatures, particularly in cooling demand, likely due to its lower thermal inertia. In contrast, masonry buildings achieved more substantial energy savings following retrofit interventions, reflecting their initially poorer thermal performance and outdated systems. Retrofit measures yielded significant energy reductions, especially in older masonry structures, with savings reaching up to 44%, underscoring the necessity of customised retrofit strategies. The validated methodology supports future wider applicability in regional energy planning and aligns with integrated initiatives aimed at balancing climate adaptation and cultural heritage preservation. Full article

The digital transition and decarbonization are strategic European objectives, supported at different levels by the Green Deal, the Energy Performance Building Directive (EPBD), and policies and tools such as the Energy Performance Certificate (EPC) and the Smart Readiness Indicator (SRI). The SRI measures a building’s ability to use intelligent technologies to reduce its consumption and increase the energy awareness of occupants for energy efficiency. Furthermore, today, it has a limited impact on national regulations and public decision-making. Its application presents challenges including those related to heritage conservation. This paper contributes to the Italian SRI framework through an experimental application in the renovation of a historic building in the metropolitan city of Reggio Calabria (Italy). The analysis evaluates the SRI’s adaptability by comparing its pre-renovated state, current state, and pre-design plan. The SRI calculation integrates assessment tools with BIM models for a potential future digital twin approach. The study, part of a funded national research project, aims to enhance policies for digitalization in the green transition. The paper is organized into the Introduction; Materials and Methods, which contains the methodological approach; Results; and Discussion and Conclusions. Following the experimental application, the results show that standardizing the SRI approach could enhance energy efficiency and digitalization in buildings. Full article

This study examines the Carbon Performance Gap (CPG) and Energy Performance Gap (EPG) of school buildings in Osijek-Baranja County in Croatia. The variance between the predicted energy efficiency of a building, as indicated by the energy performance certificate (EPC), and its actual performance in terms of energy consumption, is often referred to as the EPG while the variance between the predicted carbon emission of a building from the EPC and its actual emission is referred to as CPG. This study aims to determine the extent of CPG and EPG between actual energy consumption/carbon emission and the calculated, which is presented in EPCs of school buildings. The average EPG among the analyzed schools was found to be 71.73% while the average CPG was found to be 78.77%. The analysis also revealed a substantial average annual difference in heating costs attributable to the EPG. By addressing EPG and CPG while optimizing energy usage, educational institutions can achieve substantial cost savings and contribute significantly to sustainability goals. Full article

Buildings account for a significant share of global energy consumption and carbon emissions, making deep renovations essential for climate mitigation. Renovation passports (RPs) are an emerging concept still in the early stages of development, designed to provide structured step-by-step renovation roadmaps that prevent lock-in effects and optimise energy performance over time. However, their large-scale adoption in the European Union (EU) remains limited due to technical, financial, behavioural, and policy challenges. This study conducts a Systematic Literature Review (SLR) to identify key strategies for the successful development and large-scale implementation of RPs in EU. A total of 217 research articles from Scopus and ScienceDirect, along with 99 EU policy documents and 16 Building Performance Institute Europe (BPIE) reports, were analysed to assess the technical, financial, behavioural, and policy dimensions of RP adoption. Our findings highlight the role of digital tools like Building Information Modelling (BIM), digital building logbooks (DBLs), and one-stop shops (OSSs) in improving RP usability and accessibility. Financial barriers, such as high upfront costs and fragmented funding, require harmonised incentives, green loans, and energy performance contracting. Behavioural factors, including homeowner awareness, trust in renovation services, and decision-making complexity, also influence RP adoption. This study underscores the need for stronger policy integration between RPs and energy performance certificates (EPCs), improved financial instruments, and enhanced stakeholder engagement. By addressing these gaps, this research provides actionable recommendations for policymakers and stakeholders to accelerate the adoption of RPs and contribute to the EU’s Renovation Wave strategy and broader climate neutrality objectives. Full article

To effectively decarbonize Europe’s building stock, it is crucial to monitor the progress of energy consumption and the associated emissions. This study addresses the challenge by developing a national-scale urban building energy model (nUBEM) using artificial intelligence to predict non-renewable primary energy consumption and associated GHG emissions for residential buildings. Applied to the case study of Spain, the nUBEM leverages open data from energy performance certificates (EPCs), cadastral records, INSPIRE cadastre data, digital terrain models (DTM), and national statistics, all aligned with European directives, ensuring adaptability across EU member states with similar open data frameworks. Using the XGBoost machine learning algorithm, the model analyzes the physical and geometrical characteristics of residential buildings in Spain. Our findings indicate that the XGBoost algorithm outperforms other techniques estimating building-level energy consumption and emissions. The nUBEM offers granular information on energy performance building-by-building related to their physical and geometrical characteristics. The results achieved surpass those of previous studies, demonstrating the model’s accuracy and potential impact. The nUBEM is a powerful tool for analyzing residential building stock and supporting data-driven decarbonization strategies. By providing reliable progress indicators for renovation policies, the methodology enhances compliance with EU directives and offers a scalable framework for monitoring decarbonization progress across Europe. Full article