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Review and Analysis of Models for a European Digital Building Logbook
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.
Journal Article
Building Energy Performance Certificate—A Relevant Indicator of Actual Energy Consumption and Savings?
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).
Journal Article
Energy Efficiency in Buildings: The Gap Between Energy Certification Methods and Real Performances
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.
Journal Article
Analyzing the Carbon Performance Gap and Thermal Energy Performance Gap of School Buildings in Osijek-Baranja County, Croatia
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.
Journal Article
Consequences of Non-Compliance with Technological Procedures in the Realisation of Construction Objects from the Point of View of Heat Consumption for Heating—A Case Study on Selected Construction Sites in the Slovak Republic
This article focuses on the energy performance of buildings with an emphasis on the consequences of non-compliance with technological practices during the building process. We analyse the impact of construction deficiencies on the consumption of heat for heating, focusing on specific case studies of selected building constructions in the Slovak Republic. The results show that non-compliance with prescribed technological standards and procedures leads to significant deterioration in the building’s energy efficiency, which is manifested in increased heat consumption and higher operating costs. The findings of this study have key importance for future construction projects as they offer valuable recommendations for improving energy standards and construction quality, thus contributing to a more sustainable and efficient building process. When designing buildings with near-zero energy demand, it is necessary to eliminate all risks in the project that arise during the preparation and design itself, as well as during implementation.
Journal Article
Implementing energy subsidy reforms
Poorly implemented energy subsidies are economically costly to taxpayers and damage the environment. This report aims at providing the emerging lessons form a representative sample of case studies in 20 developing countries that could help policy makers to address implementation challenges, including overcoming political economy and affordability constraints. The sample has selected on the basis of a number of criteria, including the countrys level of development (and consumption), developing country region, energy security and the fuel it subsidies (petroleum fuel, electricity, natural gas). The case studies were supported by data collection related to direct budgetary subsidies, fuel and electricity tariffs, and household survey data.The analysis provides strong evidence of the success of reforms in reducing the associated fiscal burden. For the sample of countries, the average energy subsidy recorded in the budget was reduced from 1.8% in 2004 to 1.3%GDP in 2010. The reduction of subsidies is particularly remarkable for net energy importers. Pass-through of international fuel prices was also notable in the case of electricity generated by fossil fuel. For the sample of countries, the average end-user electricity tariff increased by 50%, from USD 6 cents in 2002 to USD 9 cents per kWh in 2010.In spite of the relatively price inelastic demand for gasoline and diesel, fossil fuel consumption in the road sector (per unit of GDP) declined in the 20 countries examined from 53 (44) in 2002 to about 23 kt oil equivalent per million of GDP in 2008 in the case of gasoline (Diesel). The most notable decline in consumption was recorded in the low and lower middle income countries. This reflects the much higher rate of growth in GDP in this group of countries and underlines the opportunities to influence future consumption behavior rather than modifying
the existing consumption patterns, overcoming inertia and vested interests. Similar trends are recorded for power consumption.While there is no one-size-fits-all model for subsidy reform, implementation of compensatory social policies and an effective communication strategy, before the changes are introduced, reduces helped with the implementation of reforms.
eBook
Energy Performance Certificate Classes Rating Methods Tested with Data: How Does the Application of Minimum Energy Performance Standards to Worst-Performing Buildings Affect Renovation Rates, Costs, Emissions, Energy Consumption?
Energy renovations of the building stock are a paramount objective of the European Union (EU) to combat climate change. A tool for renovation progress monitoring is energy performance certificate (EPC) labelling. The present study tested the effect of different EPC label classifications on a national database, which comprises ~25,000 EPC values from apartment buildings, detached houses, office buildings, and educational, commercial, and service buildings. Analysing the EPC classes labelling resulting from four different EU methods, we estimated the annual renovation rates, costs, energy savings, and CO2 emissions reduction that would affect the national building stock if each of them was adopted, to fulfil the European Climate Target Plan by the year 2033. The ISO 52003-1:2017 two-point and one-point methods determined a very uneven distribution of renovation rates, from 0.45% to ~9%. Conversely, the Directive 15% recently proposed in COM/2021/802 with uniform rates determined smaller differences and standard deviation, not pushing renovations above 3.70%, namely a rate that once fine-tuned can stimulate realistic, yet effective renovation campaigns. The major differences in renovation rates provided by the studied methods show the need for a harmonized strategy such as the Directive proposal to enable achievement of European targets.
Journal Article
Complementary Methodology for Energy Efficiency Ratio-Based Assessments with Change-Point Model Parameters
The energy consumption of existing buildings is not only affected by their physical features but also by their business activities (e.g., operating hours, number of workers, and climate). Energy Star’s energy efficiency ratio (EER) is a key energy performance indicator that has been used for more than 20 years. This method normalizes operation characteristics by calculating the estimated energy consumption of business activities using regression models and comparing it with the actual energy consumption. However, EER-based assessment is limited by the lack of information regarding the reasons for the evaluation results. This study proposes a balanced method for explaining the reasons underlying energy efficiency levels while maintaining the existing EER assessment system. The method constitutes data collection, EPI derivation, and energy performance assessment, utilizing the parameters of the change-point linear model (CPM) as an additional EPI to provide descriptive information. The results are summarized to provide a checklist guide for retrofitting, and additional energy saving potential for buildings with low and high scores can be identified by comparing the EER scores and CPM parameters. The proposed method shows that it is possible to interpret the energy efficiency assessment results by comparing CPM parameters, while maintaining the EER score.
Journal Article
Evaluation of Model Calibration Method for Simulation Performance of a Public Hospital in Brazil
This work presents an extensive study on methodologies to calibrate electric energy consumption in buildings. A comparison between several calibration methodologies shows different approaches addressing the same issue, suggesting a lack of a unique methodology that is reproducible for every building. Additionally, no methodology fits the Brazilian public context, such as the predominance of Unitary Air Conditioning Systems (UACS) and buildings which have operated for more than 30 years. A new calibration methodology for performance simulation is proposed to deal with such features. The methodology is separated into two evidence-based steps according to the size of the Heating, Ventilation and Air Conditioning (HVAC) systems used to control buildings’ indoor environments: the first step is dedicated to calibrating medium- and large-sized HVAC systems, and the second step is dedicated to calibrating small-sized HVAC systems. University Hospital of University of São Paulo (UH-USP) is used as a test bed to implement the proposed methodology. Accuracy indicators show the efficiency of the methodology in terms of calibrating a simulation of the whole UH-USP building and Chilled Water Plant on a monthly basis in terms of accuracy and the time needed to perform the calibration. However, regarding simulation of UACS, the application of the methodology was inconclusive. This study leaves open the question of the trade-off between increasing model outcome accuracy and the strictness of accuracy indicators applied to UACS and poorly automated large-sized air conditioners.
Journal Article