Energy Performance Certificates Research Articles

Field study of energy and environmental performance of ground source heat pumps retrofitted in a cluster of UK social housing dwellings

This paper uses an empirical field based approach to examine seasonal variation in heat pump electricity use and indoor temperatures across a cluster of 50 social housing dwellings retrofitted with ground source heat pumps (GSHP). The case study dwellings were co-located in a socially deprived housing estate in Oxford (UK). Time series monitoring data was collected on indoor, outdoor and target temperatures, heat pump electricity use (kWh), space heating and hot water operation status (on/off) in non-heating and heating seasons. Contextual data about the dwellings were gathered through heat pump surveys and energy performance certificates. Results showed 60% rise in electricity use during the heating season with statistically significant correlation observed between indoor and target temperatures, energy efficiency rating and monthly electricity use. When electricity use was normalised for outdoor temperature, lower electricity use per heating degree day (HDD) was observed in the heating season in the majority of dwellings, confirming the efficient running of the heat pumps. Mean daily indoor temperatures were found to be stable across majority of dwellings, with peak electricity use largely happening outside of the national evening peak period of 4pm-7pm. Despite there being a ‘Timer’ mode in relation to outside weather, most of the residents used the ‘Manual’ mode of operation to adjust target temperatures, possibly to overcome the low output temperatures of heat pumps. While resident training will help to enhance understanding of heating controls, smarter operation of heat pumps through automation based on optimisation of indoor and outdoor temperature, occupancy patterns, heating preferences and electricity price signals could result in further energy savings.

Energy Performance Certificate Estimation at Large Scale Based on Open Data

This paper presents an innovative methodology for enhancing energy efficiency assessment procedures in the built environment, with a focus on the Switzerland’s Energy Strategy 2050. The current methodology necessitates intensive expert surveys, leading to substantial time and cost implications. Also, such a process can’t be scaled to a large number of buildings.Using machine learning techniques, the estimation process is augmented and exploit open data resources. Utilizing a robust dataset exceeding 70’000 energy performance certificates (CECB), the method devises a two-stage ML approach to forecast energy performance. The first phase involves data reconstruction from online repositories, while the second employs a regression algorithm to estimate the energy efficiency.The proposed approach addresses the limitations of existing machine learning methods by offering finer prediction granularity and incorporating readily available data. The results show a commendable degree of prediction accuracy, particularly for single-family residences. Despite this, the study reveals a demand for further granular data, and underlines privacy concerns associated with such data collection. In summary, this investigation provides a significant contribution to the enhancement of energy efficiency assessment methodologies and policy-making.

Identifying Hard-to-Decarbonize houses from multi-source data in Cambridge, UK

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.

Shrinking homes? The geographies of small domestic properties in London, 2010–2021

In the last decade, the UK’s media have highlighted an apparent rise in the number of homes below the recommended Nationally Described Space Standard for a one-person, one-bed home. However, evidence for the growth of ‘micro-apartments’ is mixed, with existing data making it difficult to map the geographies of sub-standard homes below the Local Authority scale. Focussing on London, this paper uses Energy Performance Certificates (EPCs) as a source of floorspace data, matching this to the Land Registry’s Price Paid Data (PPD) and information from the London Planning Database. It quantifies the number of sub-standard homes in London registered for an EPC 2010–21, maps their location at the MSOA (neighbourhood) level, and compares property prices for small and larger homes. Focusing on newly-built homes, it shows that the numbers of small homes doubled across this period with growth in select outer London ‘hotspots’ accounting for much of this. It also demonstrates the overall numbers of small homes rose despite the formal incorporation of NDSS in the London Plan 2016, with the by-passing of space standards in property conversions under Permitted Development Rights, 2013–21 appearing relatively insignificant in explaining these temporal and spatial trends. Finally, it shows that the price per square metre of small homes often far exceeds that of much larger homes in the same area. While recognising the limitations of EPC data, our findings point to the need for further exploration of the enforcement of space standards, not least because it is often assumed that building more, smaller homes in the capital will create more affordable homes for Londoners.

Envisioning an Energy Performance Certificate for livestock houses: A general methodological development and a specific application to growing-finishing pig houses

Climate control represents a significant energy use in livestock houses. Although energy-efficient solutions aimed at reducing this energy consumption are expanding, their spread in these facilities is hindered by the lack of standardized methodologies for assessing their impacts on the energy performance. An Energy Performance Certificate (EPC) for livestock houses represents a solid solution for assessing and rating the energy performance of these buildings accordingly to a standardized methodology. Unfortunately, specific EPC s for livestock houses are not present in literature. The aim of this work is to propose the first methodological framework for an EPC specifically developed for livestock houses which can be easily adapted to different types of livestock productions. An exemplificative adaptation and a practical application are provided for growing-finishing pig houses with the aim of clarifying the certification procedure, highlighting the potentialities of this approach, and providing and discussing some examples of results. The results show that the certified pig house has a low energy performance, labelled with the class E. By adopting the energy efficiency measures proposed in the framework of the EPC, the energy performance could remarkably improve and achieve a class-B rating. This EPC proposal represents a complete novelty in literature and an innovative and promising approach to the topic of energy efficiency in livestock sector by enhancing the comparison of the energy performance between existing livestock houses or design alternatives equipped with different energy-efficient technologies and solutions.

A Study for the Improvement of the Energy Performance Certificate (EPC) System in Turkey

This study aims to examine the current status of Turkey’s energy consumption and energy performance system and draw improvements. To this aim, this study adopted a qualitative research method. A literature review was conducted regarding the problems related to the EPC system. Following this, a series of research questions were derived, and answers were sought through expert group interviews. The problems were categorized into three headings: the EPC system and calculation problems, problems in the regulation and inspection process and, finally, the perspective on the construction industry to the EPC system is examined in the case of Turkey. Deficiencies in the rating system and calculation, regulation and inspection, and perspective of the EPC system in Turkey were identified. Suggestions for the development of EPC in Turkey were made to make it comparable with the systems in EU countries. As one of the outcomes of the study, Turkey should focus on the use of renewable energy, taking into account its geographical advantage. In addition, a more detailed micro-zoning that focuses on regional differences should be carried out, and the authorities should introduce a better control mechanism for the EPC system.

Diagnosis of the building stock using Energy Performance Certificates for urban energy planning in Mediterranean compact cities. Case of study: The city of València in Spain.

This research aims to diagnose the energy performance of buildings in València and identify areas where energy efficiency can be improved. The energy performance results of all 129,487 EPCs in the city were mapped and compared to socioeconomic variables to gain insights into the reasons behind the results. The study reveals that the city’s building stock has poor energy performance, attributed to the lack of building standards during the city’s expansion in the 1960s and 1970s. The worst energy performances are observed in the peripheral districts, particularly in the city’s northern half, where low-income and low-renting rates are common, resulting in reduced investment capacity for individuals to retrofit their homes. To promote quick dissemination of measures to retrofit households, they must be adequate, economical, and replicable, avoiding social, administrative, and economic barriers. The study highlights the importance of EPCs as an objective tool to diagnose the energy efficiency of a city’s building stock. Policymakers can use the findings to identify areas that require improvements and evaluate the appropriate actions to improve the building stock’s energy performance. This study presents significant potential to reduce buildings’ energy demand and achieve climate goals through EPCs.

Mapping residential air pollution hotspots using freely available Energy Performance Certificates in England and Wales

Mapping residential air pollution hotspots using freely available Energy Performance Certificates in England and Wales

Assessing the co-heating test as reference for heat loss coefficient estimation: In-depth analysis on an artificial dataset

In order to bridge the building energy performance gap it is necessary to quantitatively and qualitatively characterize the actual energy demand of buildings and the thermal behaviour of their envelopes. Current European legislation prescribes the assessment of the energy efficiency of the building stock by means of energy performance certification, which labels the building performance based on theoretical data and specifications reflecting the design phase. At the current state, in most European countries such certificates provide the only insight into the overall performance of the building stock, while the need of characterizing the actually achieved building behaviour is recognized. The most common testing procedure used with the aim of characterizing the as-built thermal performance of commissioned dwellings is the co-heating test. It consists of a prescribed measurement procedure where a vacated house is submitted to an elevated indoor temperature. During the experiment, the indoor and outdoor environment, as well as the energy demand needed to maintain the stable indoor temperature are precisely monitored. Up to date, this testing procedure is acknowledged as the most reliable in practice, however, the limitations of the methodology are not yet completely explored and unambiguously defined. Thus, the aim of this work is to explore the limits of the co-heating testing procedure on artificially generated experiments which provide a completely defined environment and reference targets. To assess the impact of different aspects, such as the parameters of the statistical models or monitoring period and length, the artificial datasets provide the ideal conditions since the impact of measurement inaccuracy can be avoided and the expectations of the methodology itself can be evaluated. The main findings complement the prevalent research and indicate the possibility of assessing the building performance in the 10% bounds from the target, however considering idealised monitoring data. The research shows that using global horizontal instead of south vertical irradiation can provide overall more accurate results, especially in transient months. Finally, when assessing suitable periods for performing tests in a moderate climate, only 20% of the whole year can be considered to yield satisfactory results.

Aerial urban observation to enhance energy assessment and planning towards climate-neutrality: A pilot application to the city of Turin

Based on the central role of cities in the decarbonisation process, this study aims at providing a novel methodology to assess and optimize the building energy demand and photovoltaic producibility at city scale. This is done by exploring the potential of aerial acquisition of local-scale thermographic data to integrate the existing database on building Energy Performance Certificates, on which the EU energy assessment and retrofit policies are based, on a dedicated GIS platform. Once the method is validated through testing the reliability of the resulting energy classification of buildings, the approach is used to esteem the energy demand and potential energy production in the current state and two alternative retrofit scenarios for a large district in Turin, Italy. For the analysed scenarios, potential savings are quantified up to 20 GWh and 5000 tCO2 yearly, decreasing by more than 70 % primary energy and CO2 emissions when photovoltaic panels and heat pumps are optimally used and integrated to the existing district heating system. Conclusions remark the potential of this tool to support urban policy making and governance, also with the future perspective of a thematic urban digital twin for planning energy retrofit intervention and large scale implementation of Renewable Energy Communities.

How well do building energy performance certificates predict heat loss?

This paper evaluates the predictive power of building energy performance certificates on home heat loss. Improving the insulative capacity of residential properties is a policy priority in many markets, with building energy performance certificates serving as a benchmark. We exploit a rich panel dataset of high-frequency thermostat readings, coupled with data detailing weather and building characteristics, to identify an ex-post metric of heat loss. Our results show a significant effect of building energy performance rating on indoor temperature, a proxy for home heat loss. However, we do not find evidence of a distinct gradient in performance between building energy rating categories, as suggested by ex-ante estimates of home heat loss. The finding highlights that directly linking policy targets to a particular energy performance certificate standard can lead to an outcome that deviates significantly from what is anticipated.

A novel multicriteria methodology to assess the renovation of social buildings

The current Energy Performance Certificates of buildings are mostly based on the expected energy consumption. Recently, some certification schemes are starting to incorporate Indoor Air Quality aspects, but it is still not usual. Another topic of interest, such as energy poverty, is not considered in current certification schemes either. This paper presents a novel multicriteria methodology to assess the renovation of social housing buildings: the ARCAS methodology. The novelty lies in its transversal approach, which considers three axes: Energy Efficiency, Energy Poverty, and Indoor Environment Quality. The indicators set for assessment are calculated based on actual on-site measurements. The methodology has been tested in six demonstrator buildings selected throughout the SUDOE territory (southwestern Europe). The results show that the ARCAS methodology allows a comprehensive assessment of the current situation of the building to be achieved and helps to propose the renovation measures in a specific direction. Advice and guidance for professionals who want to test the methodology are also given. Although the methodology has been developed for its application in social housing, according to the EU recommendations, it can be applied to any type of housing.

Comparison of calculation and consumption methods for determining Energy Performance Certificates (EPC) in the case of multi-family residential buildings in Poland (Central-Eastern Europe)

The calculation method and the consumption method are used to award Energy Performance Certificates (EPC), in accordance with the Energy Performance of Buildings Directive (EPBD) 2010/31/EU with revisions. The calculation method can be used for any type of building, regardless of the type of heat source. A good knowledge of the building is required (architectural and construction documentation, inventory of the building). The consumption method can be used only in buildings with heat and gas meters. It is not necessary to have detailed information about the building. However, this method is not applicable to offices, hotels, or production buildings with periodic breaks in heating and hot water consumption. Here, we apply the calculation method and the consumption method to analyse 15 multi-family residential buildings located in Poland (Central-Eastern Europe). Both methods gave similar values. Using the consumption method the energy indicators were slightly lower than using calculation method (on average, the results differed by approx. 14–17%). The consumption method provides a useful alternative to the calculation method, and can be tested by the scientific and expert community in other countries where it has not yet been implemented.

Residents' participation in energy performance certification for collective action on climate change: the case of EnerGuide.

Although governments have launched energy performance certification (EPC) programs to increase residential energy efficiency, residents' perception and acceptance of these programs have been little studied. This study contextualizes residents' intentions to participate in EPC programs in terms of their attributions to and attitudes toward climate change to find mediating factors and effects to help trigger collective action to reduce residential sector energy demand. This study employed a partial least squares structural equation modeling approach to empirically analyze a survey conducted on 400 residents of Edmonton, Canada, who participated in the Canadian energy efficiency rating and labeling program, EnerGuide. Using EnerGuide, a Canadian energy efficiency rating and labeling program, as an example, this study establishes a framework to explain that local residents' internal and external attributions to climate change elicit positive attitudes (need to take action), increasing their recognition of energy efficiency program benefits, which further promotes their EnerGuide program acceptance and participation intentions. This study also reveals the mediating effects between variables. Residents' attitudes toward climate change mediate the relationship between internal/external attributions and EnerGuide program acceptance, and they indirectly impact residents' program acceptance and participation intentions, with this effect moderated by energy efficiency program benefits. Residents' program acceptance also mediates the relationship between climate change attitudes/energy efficiency program benefits and the intention outcome. The study provides an example of the use of climate change discourse to motivate residents' energy efficiency program participation.

Optimizing building retrofit through data analytics: A study of multi-objective optimization and surrogate models derived from energy performance certificates

The building stock is responsible for a large share of global energy consumption and greenhouse gas emissions, therefore, it is critical to promote building retrofit to achieve the proposed carbon and energy neutrality goals. One of the policies implemented in recent years was the Energy Performance Certificate (EPC) policy, which proposes building stock benchmarking to identify buildings that require rehabilitation. However, research shows that these mechanisms fail to engage stakeholders in the retrofit process because it is widely seen as a mandatory and complex bureaucracy. This study makes use of an EPC database to integrate machine learning techniques with multi-objective optimization and develop an interface capable of (1) predicting a building’s, or household’s, energy needs; and (2) providing the user with optimum retrofit solutions, costs, and return on investment. The goal is to provide an open-source, easy-to-use interface that guides the user in the building retrofit process. The energy and EPC prediction models show a coefficient of determination (R2) of 0.84 and 0.79, and the optimization results for one case study EPC with a 2000€ budget limit in Évora, Portugal, show decreases of up to 60% in energy needs and return on investments of up to 7 in 3 years.

Urban Building Energy Modelling for the Renovation Wave: A Bespoke Approach Based on EPC Databases

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.

Using Lean-and-Green Supersaturated Poly-Factorial Mini Datasets to Profile Energy Consumption Performance for an Apartment Unit

The Renovation Wave for Europe initiative aspires to materialize the progressive greening of 85–95% of the continental older building stock as part of the European Green Deal objectives to reduce emissions and energy use. To realistically predict the energy performance even for a single apartment building is a difficult problem. This is because an apartment unit is inherently a customized construction which is subject to year-round occupant use. We use a standardized energy consumption response approach to accelerate the setting-up of the problem in pertinent energy engineering terms. Nationally instituted Energy Performance Certification databases provide validated energy consumption information by taking into account an apartment unit’s specific shell characteristics along with its installed electromechanical system configuration. Such a pre-engineered framework facilitates the effect evaluation of any proposed modifications on the energy performance of a building. Treating a vast building stock requires a mass-customization approach. Therefore, a lean-and-green, industrial-level problem-solving strategy is pursued. The TEE-KENAK Energy Certification database platform is used to parametrize a real standalone apartment. A supersaturated mini dataset was planned and collected to screen as many as 24 controlling factors, which included apartment shell layout details in association with the electromechanical systems arrangements. Main effects plots, best-subsets partial least squares, and entropic (Shannon) mutual information predictions—supplemented with optimal shrinkage estimations—formed the recommended profiler toolset. Four leading modifications were found to be statistically significant: (1) the thermal insulation of the roof, (2) the gas-sourced heating systems, (3) the automatic control category type ‘A’, and (4) the thermal insulation of the walls. The optimal profiling delivered an energy consumption projection of 110.4 kWh/m2 (energy status ‘B’) for the apartment—an almost 20% reduction in energy consumption while also achieving upgrading from the original ‘C’ energy status. The proposed approach may aid energy engineers to make general empirical screening predictions in an expedient manner by simultaneously considering the apartment unit’s structural configuration as well as its installed electromechanical systems arrangement.

Energy performance gap of the Italian residential building stock: Parametric energy simulations for theoretical deviation assessment from standard conditions

Energy Performance Gap (EPG) is a crucial issue in the building sector that can lead to an overestimation of the national energy policies. It is the difference between the calculated energy consumption and actual energy use, and it is relevant mainly for space heating. As EPG quantification or correction methods could lead to more realistic energy policies, EPG has become a focus of many studies and research. In this framework, this study aims to quantify the theoretical deviation of EPG, i.e., concerning to the standard conditions, for the Italian residential building stock by performing parametric energy simulations of thousands of representative reference buildings. After a comprehensive thermophysical characterization of the national building stock, parametric simulations were carried out by varying the main standard conditions set in the Energy Performance Certificate (EPC) calculation. This approach allowed the quantification of EPG according to the climatic zone, building type, usage profile, and thermal insulation level of buildings, while also analysing the influence of these parameters on the EPG and checking for prebound or rebound effects (i.e. when standard consumption is greater or smaller than actual one). The study identified a range of EPG variability for both prebound (0% to +80%) and rebound (−30% to 0%) effects and quantified an average EPG between −3 and +16 kWh per heating degree day of the selected location as a function of the usage profile. This work represents the first attempt to calculate the EPG of the Italian residential building stock and it could lead to the correction of the national energy policies implemented in the building sector.

Automated energy performance certificate based urban building energy modelling approach for predicting heat load profiles of districts

Urban building energy modelling (UBEM) for analysing buildings in their spatial and functional context is an arising method. Only a few UBEM procedures use detailed building simulation tools, which are essential for high temporal and spatial resolution. This paper aims at developing a detailed automated physical bottom-up UBEM framework based on archetypes using Energy Performance Certificate data for predicting hourly heat load profiles of residential buildings. Simulation results are compared to and validated with measurements of two district heating networks and values from the TABULA typology. A comparison of the simulated hourly heat load profile for space heating and domestic hot water with measurement data results in a CV(RMSE) of 0.3, NMBE of 0.085, R2 of 0.85 and r of 0.94 for a sample size of 66 residential buildings, solely based on an estimation of the 3 classification criteria of the archetypes (building period, building condition and building type) and an estimation of the conditioned gross floor area for each measured building. Hence, the model can be declared as calibrated according to acceptance criteria in literature.

Analysis of Swedish school buildings’ energy performance certificates with focus on ventilation systems

Energy performance certificates are valuable sources of information about buildings. They are primarily used to assess the buildings’ energy performance, however the data included can also be used for building stock description or analysis from different perspectives. School buildings account for a substantial part of the Swedish public building stock and represent a great opportunity for implementation of energy saving strategies. To improve the energy efficiency, it is first important to analyse and understand the current energy use and identify the key factors responsible for most of the energy use. In Sweden, data used for EPC compilation are in most cases real measured data opposite to other European countries where EPC comprises calculated data practices. Therefore, the energy performance value provides a much more realistic representation of the building energy use. This study analyses certain aspects of school buildings’ energy performance using data available in EPCs, such as year of construction, floor area, heat supply systems and ventilation system. Comparison with data from some other European countries is also presented. The data which could be included in the certificate to extend the potential of EPC use in other areas, such as evaluation of indoor environmental quality, is also discussed.