Zero Energy Buildings Research Articles

A Roadmap for the Certification of Polyurethane Flexible Connectors Used as Envelope Products in the Next Generation of Healthy, Nearly Zero-Energy Buildings

Currently, in the European Economic Area (EEA), producers of building materials are implementing innovative solutions that provide a chance for the widespread construction of zero-emission and zero-energy buildings. However, they encounter legal barriers related to the lack of standardization procedures enabling the rapid placement of innovative construction products on the market. The European project Horizon 2020: Measuring Envelope Products and Systems Contributing to the Next Generation of Healthy, Nearly Zero-Energy Buildings (MEZeroE) aims to support producers of innovative envelope products used in zero-energy buildings, including in the field of certification, CE (European Conformity), marking and placing them relatively quickly on the market. This article presents one of the research procedures developed and tested by Pilot Measurement & Verification Lines (PM&VL7) as part of the MEZeroE project for Flex&Robust polyurethane flexible connectors. This procedure considers the applicable legal requirements regarding CE marking and also indicates a certification path for this type of product.

A Comprehensive Approach to Nearly Zero Energy Buildings and Districts: Analysis of a Region Undergoing Energy Transition

This paper explores the development of positive energy communities using Eordaia, Greece, as a case study. The approach combines building and district-level energy analysis to achieve nearly zero energy performance through retrofitting, district-level storage systems, and renewable energy technologies. A parametric analysis utilizing RETSCREEN Expert and EnergyPlan software determines the optimal mix of technologies based on technical and financial parameters, with Eordaia, a region in energy transition and part of the RESPONSE Horizon project, illustrating the practical benefits. It includes a neighborhood of 105 mixed-use properties and two municipal buildings where a range of renewable energy sources and energy efficiency measures are applied. Insulation, photovoltaic systems, LED lighting, predictive thermostats, and windows coated with nanotechnology are some of the key interventions considered. The findings show considerable reductions in CO2 emissions and energy use, with payback periods ranging from 8.7 to 9.6 years. This study underscores the value of district-level strategies over individual building retrofits, highlighting cost savings and improved energy performance. These findings offer valuable insights for urban planners and policymakers aiming to transform urban areas into sustainable, positive energy districts, supporting the EU’s 2050 net-zero emissions goals.

Thermal Performance Analysis and Design Evolution of Ventilated Stone Facades: A Case Study of the Praski Student House (Akademik Praski) in Warsaw

The rationale for this work arose from the urgency of improving the energy efficiency of buildings at the design stage, given the changing requirements of energy efficiency standards such as the Polish Technical Conditions (WT 2014 and WT 2020). This research is novel as there is currently limited information available on the improvement of the thermal performance of ventilated stone facade systems, although they are now widely used due to their practical and aesthetic advantages. The first objective of this work is to evaluate the thermal performance of the ventilated facades of the Praski Student House (Akademik Praski) and to assess how certain design variations can help achieve a lower level of energy consumption. Using a comprehensive case study approach, this study provides accurate thermal calculations of the facade to assess its global thermal insulation coefficient (Rt) and thermal transmittance (Uc). The improvement in the actual U-value from the original design is as follows: the U-value is reduced from 0.33 originally to 0.228 for WT 2014 and to 0.198 for WT 2020, showing a reduction of about 30.9% and 13.2%, respectively. These results indicate the energy efficiency of increased insulation thickness and optimally oriented air gap dimensions. The practical contributions of this research are valuable for architects, engineers, and contractors involved in the design and construction process of buildings aiming to achieve near-zero energy buildings (nZEBs), including concrete suggestions on how to improve current construction practices as well as material recommendations. There is a need for durability studies, for example to assess the performance of such facades under different climatic conditions, as part of future work to support these findings.

Cost-Effectiveness Analysis of Nearly Zero-Carbon Office Buildings in Taiwan

The formulation of an affordable and economically-feasible policy for nearly zero-carbon building design is a challenge that countries encounter in promoting net-zero building. In 2022, Taiwan promulgated Building Energy Rating System (BERS), the world's first building energy efficiency assessment system tailored for subtropical climates, as a basis for evaluating its goal of achieving nearly zero-carbon buildings by 2050. However, whether this nearly zero-carbon building policy is financially feasible has remained unknown to the government and the industry. To address the issue, the objective of the paper is to conduct a cost-benefit and payback period analysis of newly constructed nearly zero-carbon office buildings in accordance with the Building Energy-efficiency Rating System for New Buildings (BERSn) assessment framework, and thereby examines the financial affordability and feasibility of Taiwan's net-zero building policies.Firstly, this study introduces existing building energy performance evaluation methods in Europe, America, and Japan, and explains the methodology of Taiwan's Building Energy Rating System (BERS). The paper then reviews international Cost-Benefit Analyses of Nearly Zero Energy Office Buildings and parallelly conducts a Cost-Benefit Analysis of Nearly Zero-Carbon Office Buildings in Taiwan. Following the BERS methodology, this paper identifies the baseline efficiency level and the Nearly Zero-Carbon Building (NZCB) efficiency level, along with their associated solutions and investment costs, for air conditioning and lighting systems. In this study, a questionnaire survey of 28 experts identifies the air conditioning unit costs of Basic Mechanical Equipment Efficiency (BME) and energy-saving control technologies (R) for energy-efficient design of Fan Coil Unit (FCU), Air Handling Unit (AHU), and Variable Refrigerant Flow (VRF) system. Accordingly, 33 air conditioning design solutions and their corresponding construction costs complying with the BERSn requirements of EAC≦0.5 for nearly-zero carbon office buildings are identified. Regarding the nearly zero-carbon lighting design, the simulations reveal that the use of LED panel luminaires or T8 LED luminaires (including those with energy-saving labels) can achieve an average operational lighting illuminance of 500 LUX and the BERSn requirements of EL ≤ 0.5 for lighting. Finally, the study further analyzes the payback period and premium cost ratio of NZCB by employing the budget data of seven building projects. The analysis shows that the premium cost ratio and the payback period of NZCB range from 1.33%-1.50% and 6.4-7.7 years, respectively. The results demonstrate that while a higher budget is commonly associated with NZCB by the public, it is in fact economically and technologically feasible to realize NZCB with prevailing energy-efficient measures.

Assessing the performance of smart buildings and smart retrofit interventions through key performance indicators: Defining minimum performance thresholds

Smart technologies play a vital role in facilitating the response of buildings to the external conditions, including climate, grid, and the internal building requirements such as user needs. A salient concern lingers in relation to existing buildings due to their increasing energy consumption. Around 35 % of EU buildings are older than 50 years and 90 % are built before the nineties. In this sense, smart retrofitting represents a key step towards achieving energy-responsive flexible buildings. Quantifying building energy performance with appropriate Key Performance Indicators is a critical step towards achieving decarbonization goals in both existing and new buildings. In this paper a group of five representative indicators has been selected to measure the energy performance of smart features in retrofitted and new buildings, also identifying distinct performance thresholds. Therefore, each threshold defines minimum acceptable and top performing values for the indicators. Accordingly, thresholds are set first based on previous literature and performance data, then a Logical Evaluation Methodology is used to identify suitable range of thresholds. Results of this paper propose a quantified definition for smart retrofitting, which involves transforming an existing building into a Smart Building. A smart building is a nearly Zero Energy Building that achieves primary energy savings of 30 % to 80 % and can adapt to changing climate and grid conditions. It should communicate with users and predict operational failures using a Building Energy Management System. Additionally, it should enable load shifting in response to renewable energy source production and electricity prices by 30 % to 70 % annually, while minimizing grid interaction to 10 % to 30 % on an hourly basis throughout the year. Furthermore, it should allow for RES self-consumption of 30 % to 70 % and cover 20 % to 70 % of the load with RES annually. Finally, the indicators are tested on a case study in Italy within a Horizon 2020 project to validate the thresholds.

Design of a hybrid solar and biomass-based energy system integrated with near-zero energy building: Techno-environment investigation and multicriteria optimization

The current research aims to meet the energy needs of a group of residential buildings in Norway with the least amount of carbon dioxide emission and the greatest amount of renewable energy. The supply side based on the renewable renewable-based energy system is planned and scaled using the real-time data use of domestic hot water (DHW), heating and electricity necessary for the buildings. PVT panels are used in the hybrid solar and biomass-based energy systems to produce both the DHW requirements and the electricity production. The digester is used with the heat pump, which generates heat. A double-effect absorption refrigeration system is also utilized to provide the necessary cooling requirements. On the supply side, the management of the heat streams and the redirection of flows are done using a rule-based regulating system. The whole plant's size is supplied, and the dynamic energy simulation is run. The primary deciding criteria for heating the buildings are the costs of electricity and biomass. The whole system is then optimized depending on operating circumstances, and the outcomes are compared to the design point. PVT may be used to create more than 80% of the yearly DHW. Furthermore, summertime radiation accounts for 64.8% of cooling output since it is more intense and may be converted into cooling energy. Digester/CC also contributes 66.55% of the building's heating, showing that the designers should rely on biomass as wintertime energy costs are higher. The parametric study demonstrates that increasing PVT time and tank capacity has varied effects on efficiency and emissions. Also, On winter days, there was a significant drop in renewable energy generation from summer to autumn, from 82.7 MWh to 28.52 MWh. The optimization results show that at the TOPSIS point, the total cost, efficiency, and emission index are 9.73 $/hr, 36.8%, and 7.75kg/MWh, respectively.

IAQ and ventilation measurements at the “ZEB Laboratory” office building in Norway

This study aims to assess indoor environmental quality (IEQ) within a Zero Emission Building (ZEB) office in Norway, focusing on occupant impact (CO2, temperature, humidity) and materials/substances influence (formaldehyde, particulate matter (PM2.5), total volatile organic compounds (TVOC)). It presents a detailed data collection spanning 14 months from March 30th, 2022, to June 1st, 2023.Occupancy varied significantly, affecting measured indoor air quality (IAQ) parameters, with the lowest temperatures recorded on the second floor and specific areas like the canteen experiencing temperature drops during low usage times. Relative humidity levels remained over 20% in winter despite the building's low occupancy, a notable aspect given Norway's dry winters. PM2.5 levels stayed below World Health Organization (WHO) guidelines, indicating effective pollution management.The study also evaluates the impact of reducing the ventilation rates on IAQ, noting no significant IAQ compromise. An analysis correlating IAQ measurements with building occupants' satisfaction post-intervention revealed that temperature is the most significant factor affecting satisfaction levels, excluding acoustic satisfaction. Occupants generally reported satisfaction with the indoor environmental quality (IEQ), with specific dissatisfaction tied to thermal environment and IAQ, suggesting the importance of temperature control in occupant perception.This research not only provides valuable insights into IEQ management in Zero Energy and Zero Emission office buildings but also emphasizes the critical role of indoor temperature and the potential of wooden structures to stabilize humidity levels, contributing to occupant comfort and satisfaction.

Applying the concept of zero-energy buildings in the design of cultural centers through interaction with the user

Applying the concept of zero-energy buildings in the design of cultural centers through interaction with the user

Research and Case Application of Zero-Carbon Buildings Based on Multi-System Integration Function

This study focuses on developing and implementing zero-carbon buildings through the integration of multiple systems to meet China’s carbon neutrality goals. It emphasizes the significant role of the building sector in carbon emissions and highlights the challenge of increasing energy consumption conflicting with China’s “dual carbon” targets. To address this, the research proposes a comprehensive framework that combines multifunctional envelope structure (MES) systems, photovoltaic power generation, energy storage, direct current (DC) systems, flexible energy management (PEDF), and regional energy stations. This framework integrates different technologies such as phase change materials, radiation cooling, and carbon mineralized cement, aiming to reduce carbon emissions throughout the building’s lifecycle. The method has been successfully applied in the Yazhou Bay Zero Carbon Post Station project in Sanya, Hainan, with precise calculations of carbon emission reductions. The carbon emission calculations revealed a reduction of 44.13 tons of CO2 annually, totaling 1103.31 tons over 25 years, primarily due to the rooftop photovoltaic systems. It demonstrates that the multi-system integration can reduce carbon emissions and contribute to China’s broader carbon neutrality goals. This approach, if widely adopted, could accelerate the transition to carbon-neutral buildings in China.

Development and characterization of mesoporous silica-MgSO4-MgCl2 binary salt composites for low-grade heat storage in fluidized bed systems

Achieving nearly zero-energy buildings requires the efficient utilization and storage of renewable energy. Salt-hydrate-based thermochemical energy storage (TCES) systems are promising due to their high heat storage capacity and minimal seasonal heat loss. However, challenges remain in their commercialization and large-scale application. For instance, TCES systems using magnesium sulphate (MgSO4) provide low temperature lifts due to slow reaction kinetics. Incorporating deliquescent salts like magnesium chloride (MgCl2) can enhance sorption performance but may introduce stability issues such as agglomeration and decomposition. This study presents a novel binary-salt composite combining MgSO4 and MgCl2 within commercial mesoporous silica (CMS) to address these challenges and enhance overall performance. The binary-salt composite powder, with a particle size range of 150–300 μm, is well-suited for use in fluidized-bed reactors, where fast mass and heat transfer promote efficient moisture adsorption, prevent uneven temperature distribution, and reduce agglomeration. Thermogravimetric analysis (TGA) was employed to evaluate the water sorption and desorption behaviour of MgCl2-MgSO4@CMS binary-salt composites with a total salt content of 50 wt% and salt mixing ratios of 3:1, 1:1, and 1:3. The corresponding water sorption capacities were 0.95, 0.68, and 0.57 g/g, respectively. In comparison, the MgSO4@CMS single-salt composite showed a lower water adsorption capacity of 0.47 g/g and required temperatures exceeding 150 °C for complete regeneration. Reactor-scale experiments demonstrated that the MgCl2-MgSO4@CMS composite with a 1:1 salt mixing ratio could be fluidized at low gas velocities on the order of 10−2 m/s, achieving a maximum temperature lift of 24.7 °C and an energy density of 1018 kJ/kg during hydration at 80% relative humidity and 30 °C. Additionally, the binary-salt composite showed good cyclic stability with less particle agglomeration compared to the MgCl2@CMS single-salt composite.

Driving the zero-carbon construction strategy: key barriers and enablers

PurposeIn the fast-changing field of zero-carbon construction there is a gap in understanding how zero-carbon construction strategies are experienced in practice. This paper aims to identify the key barriers and enablers to driving a zero-carbon construction strategy by industry, policymakers and educators.Design/methodology/approachThe research was conducted in two stages. The first stage used a literature review to determine thematic areas from which to develop discussion points for the second stage of the research, which gathered insights into key barriers and enablers to driving a zero-carbon construction strategy from analysing recorded discussion with industry, policymakers and educators. This study adopts a qualitative research methodological design underpinned by dialectical approach of enquiries involving 31 participants. The philosophical standpoint aligns with a constructivist participatory worldview based on multiple stakeholder perspectives. Data involving virtual and face-to-face engagement held simultaneously in Australia and India were transcribed, coded and synthesised to identify the barriers and enablers to driving zero-carbon construction strategy.FindingsThe paper identified key barriers and enablers driving zero-carbon construction strategy. Barriers included limited awareness of industry dynamics; fixed mental models of professional practice; complexities in identifying appropriate skillsets; difficulties associated with reviewing education and training models and integrating sustainable strategies at early stages of projects. Enablers included: fostering education reform and supporting frameworks and procurement strategies for developers and clients; implementing efficient building designs, construction and operationalisation of zero-carbon buildings and; utilising an industry-led integrated approach. A framework was developed to provide an illustrative view of the linkage between the research projects’ focus areas and emergent themes.Originality/valueThe paper provides zero-carbon action priorities for four significant stakeholder groups in the build environment, developers, building occupiers, educators and government. As the priorities are derived in the research from examination of current literature and analysis of stakeholder viewpoints, this paper presents a unique, realistic and timely identification of barriers and key enablers driving zero-carbon construction strategies. Methodology applied in terms of data collection involved a public discourse and a unique technology-driven collaborative approach where participants simultaneously contributed across countries and time zones in a synchronous manner across key topics related to driving the zero-carbon construction strategy.

Modelling Nigerian residential dwellings: bottom-up approach and scenario analysis

Nigeria’s residential buildings consume a substantial amount of the country’s energy, so achieving a net-zero building sector with a rapidly growing population is a key challenge. To bridge the gap in research at a national level and support Nigeria’s commitment to an unconditional 20% reduction in emissions by 2030, this study develops bottom-up archetype models of different residential building typologies to estimate the energy and material use of Nigerian residential buildings. This creates an overview of the residential stock and how different archetypes perform. The study calculates a baseline energy and material use of Nigeria’s residential building stock using the BuildME tool and converts these data into CO2 emissions using a life-cycle assessment. Scenarios are modelled for 2020. Nigeria’s residential dwellings use approximately 0.3 kt of material per dwelling over a lifetime of 50 years and 2404 kWh/yr of energy per dwelling. Annualised, dwellings emit 2500 kgCO2-eq per dwelling due to material and energy use. Scenarios proposed for meeting Nigeria’s emissions targets will require improved energy efficiency, decarbonising the building envelope through a shift in construction materials and decarbonising grid electricity. Policy relevance This study provides a comprehensive analysis of the energy and material use of residential buildings in Nigeria, focusing on achieving the country’s commitment to a 20% reduction in emissions by 2030. It employs a bottom-up approach to model energy and material use, revealing the peculiarities of the dwelling stock across Nigeria’s four climatic zones. The study explores the implications of different policy scenarios on sustainable housing. The research suggests that meeting Nigeria’s emissions targets requires improved energy efficiency, a shift in construction materials and decarbonisation of grid electricity. It also highlights the potential benefits of a policy switch to materials such as timber, earthen blocks, adobe bricks and clay, which could significantly reduce construction-related emissions. These changes could improve the quality of life of households in Nigeria, combat climate change on a global scale and bring economic advantages to Nigeria.

Multi-pronged strategies for enhancing building envelopes toward nearly-zero energy in hot climatic regions

Abstract Growing concerns about climate change and rising energy demands necessitate advancements in building energy efficiency. This study investigates the effectiveness of radiative coatings and thermal insulation, both individually and combined, in reducing energy consumption and carbon footprint for buildings in hot and humid climates. This research contributes to a growing body of knowledge by comprehensively evaluating the combined effects of these strategies. A comparative analysis was conducted using data on energy usage and carbon emissions.
The research highlights the effectiveness of envelope-enhancing techniques in reducing energy consumption and carbon emissions. The application of radiative coating led to a significant 13.1% decrease in energy usage, totaling 681.95 MWh, and corresponding emissions of 482.14 tons of CO2. Radiative coating offers the most cost-effective solution with an LCOS of $0.045/kWh. When integrating thermal insulation with radiative coating, there was a substantial 12.0% reduction in energy consumption, amounting to 690.39 MWh, and emissions of 488.11 tons of CO2. The integrated model provides significant energy savings at a slightly higher LCOS of $0.052/kWh, making it a balanced choice between efficiency and cost-effectiveness compared to using thermal insulation alone. Moreover, the study emphasizes that the combination of Glazing Integrated Photovoltaic (GIPV) with radiative coating can lead to the creation of nearly zero-energy buildings, resulting in a significant energy savings of 34.9%. These results underscore the efficacy of these technologies in achieving significant energy savings and environmental benefits.
This study demonstrates that radiative coatings significantly reduce energy consumption and carbon footprints. The combined method with thermal insulation reduces energy, suggesting further optimization strategies in hot and humid conditions. The results of this investigation recommend utilizing Glazing Integrated Photovoltaic (GIPV) to achieve nearly zero-energy buildings. Such integrated solutions not only improve energy efficiency but also make a substantial contribution to environmental sustainability in the building sector.

An exploratory factor analysis on technological-related barriers to the construction of zero-energy buildings in Nigeria

PurposeZero-energy building (ZEB) has been considered as an innovative approach to reducing building carbon emissions (CEs) and improving building energy performance. Despite huge benefits of ZEBs, there are still challenges limiting the construction of ZEBs in the construction sector. This study seeks to assess and determine the principal component of technological-related barriers to the construction of ZEBs in Nigeria.Design/methodology/approachThe study designed a questionnaire to examine the technological-related barriers to the construction of ZEBs in Nigeria. Questionnaires were administered, and 272 valid responses were elicited. Thereafter, data were analysed using descriptive and inferential statistics.FindingsThe results from the exploratory factors analysis show that the principal components of technological-related barriers to the construction of ZEBs in Nigeria are categorised into five principal components: access and awareness for technological integration and innovation; knowledge on renewable technology integration; space and complexity of sustainable energy technologies; cost and readiness for ZEB technologies; and research outcomes with practical implementation in sustainable building technologies.Originality/valueThis study contributed to more effective ZEB studies by highlighting technological-related barriers to the construction of ZEBs in construction industry. An understanding of these barriers can aid construction stakeholders, organisations, policy-makers and governments in devising strategies targeted at reducing these technological-related barriers and fostering the construction of ZEBs in construction sector. Recommendations for further study on ZEBs were also made.

Design and performance analysis of a net-zero energy building in Owerri, Nigeria

Building cooling load depends on heat gains from the outside environment. Appropriate orientation and masonry materials play vital roles in the reduction of overall thermal loads buildings. A net-zero energy building performance has been analyzed in order to ascertain the optimum orientation and wall material properties, under the climatic conditions of Owerri, Nigeria. Standard cooling load estimation techniques were employed for the determination of the diurnal interior load variations in a building incorporating renewable energy as the major energy source, and compared with the situation in a conventionally powered building. The results show a 19.28% reduction in the building’s cooling load when brick masonry was used for the wall construction. It was observed that a higher heat gain occurred when the building faced the East-West direction than when it was oriented in the North-South direction. Significant diurnal cooling loads variation as a result of radiation through the windows was also observed, with the east facing windows contributing significantly higher loads during the morning hours while the west facing windows contributed higher amounts in the evening. The economic analysis of the net-zero energy building showed an 11.63% reduction in energy cost compared to the conventional building, with a 7-year payback period for the use of Solar PV systems. Therefore, the concept of net-zero energy building will not only help in energy conservation, but also in cost savings, and the reduction of carbon footprint in the built environment.

Evaluating the Performance of Topic Modeling Techniques with Human Validation to Support Qualitative Analysis

Examining the effectiveness of machine learning techniques in analyzing engineering students’ decision-making processes through topic modeling during simulation-based design tasks is crucial for advancing educational methods and tools. Thus, this study presents a comparative analysis of different supervised and unsupervised machine learning techniques for topic modeling, along with human validation. Hence, this manuscript contributes by evaluating the effectiveness of these techniques in identifying nuanced topics within the argumentation framework and improving computational methods for assessing students’ abilities and performance levels based on their informed decisions. This study examined the decision-making processes of engineering students as they participated in a simulation-based design challenge. During this task, students were prompted to use an argumentation framework to articulate their claims, evidence, and reasoning, by recording their informed design decisions in a design journal. This study combined qualitative and computational methods to analyze the students’ design journals and ensured the accuracy of the findings through the researchers’ review and interpretations of the results. Different machine learning models, including random forest, SVM, and K-nearest neighbors (KNNs), were tested for multilabel regression, using preprocessing techniques such as TF-IDF, GloVe, and BERT embeddings. Additionally, hyperparameter optimization and model interpretability were explored, along with models like RNNs with LSTM, XGBoost, and LightGBM. The results demonstrate that both supervised and unsupervised machine learning models effectively identified nuanced topics within the argumentation framework used during the design challenge of designing a zero-energy home for a Midwestern city using a CAD/CAE simulation platform. Notably, XGBoost exhibited superior predictive accuracy in estimating topic proportions, highlighting its potential for broader application in engineering education.

ETICS measurements and prediction - Verification and validation of a predictive model for the improvement of airborne sound insulation of thick external linings

The increasing demand of the reduction of carbon emissions and the consumption of energy resources due to the construction sector leads to the concept of Zero-Energy buildings. It is therefore crucial ensuring technical and engineering compatibility between future advancements in energy efficiency and sound insulation. The sound insulation requirements for residential buildings are mandatory in Italian Regulations, tested on-site after construction completion. A noteworthy challenge is the potential synergy between specifications for energy efficiency and the sound insulation properties in building materials. This paper deals with the validation of the prediction model for the improvement of airborne sound insulation due to thick external linings, particularly materials used in ETICS (External Thermal Insulation System), based on mechanical properties of involved materials. Standard ISO 9052-1 for the determination of dynamic stiffness is intended for materials used under floating floors in dwellings. However, based on the methods of this standard, it is possible to perform measurements (with both hammer and shaker) even on thick linings materials, and use the results for the implementation of computational models for the predictions of airborne sound insulation improvement, as a function of frequency, with good accuracy.

Renovating Post-First-Energy-Regulation Housing: Achieving Nearly Zero-Energy buildings under typical and extreme warm conditions in a temperate European city

Decarbonising the built environment is essential for achieving the 2050 European objectives. Multi-family buildings comprise nearly half of Europe’s building stock, yet there is no regulation mandating all housing renovations to be Nearly Zero-Energy Buildings (NZEBs). This paper highlights the role of NZEB renovation for residential buildings constructed between the first energy regulations, after the first oil crisis, and the EPBD 2002 implementation (post-first-energy-regulation housing), as a pivotal factor towards energy transition. In Spain, this period (1980–2006) encompasses approximately 45% of existing dwellings. A case study was conducted in a city with a Cfb temperate climate, focusing on the most representative residential typology of the target period: the linear block. The study evaluates its current state and defines potential measures to meet NZEB requirements, achieving zero consumption when renovation of thermal envelope is combined with heat recovery systems, heat pumps, and PV panels.This research is based on energy simulations for two climate scenarios: the typical meteorological year (TMY, official series 1970–2000) and the most extreme warm year (EWY, 2022) in Spain. Results indicate active cooling systems are necessary for NZEB renovations in Spanish Cfb climates. Furthermore, low-temperature radiators significantly reduce heating consumption, while splits are the most suitable cooling systems. This study shows Spain is not adequately preparing its housing stock to face climate change, as most typical renovation works are based on official weather files that need updating to reflect harsher summer conditions. Finally, the study aims to encourage new policies and enhance existing regulations to address rising temperatures and heatwaves.

Building retrofitting towards net zero energy under climate change

Abstract The challenge in Net-Zero Energy Building (NZEB) retrofitting is to identify the most effective measures to address energy performance issues. This paper presents a machine learning model for optimizing retrofit measures to achieve NZEB under the influence of climate change. Specifically, the non-dominated sorting genetic algorithm (NSGA-III) minimizes energy consumption and the predicted percentage of dissatisfaction (PPD) while achieving a NZE balance, thereby obtaining the Pareto front. The Order of Preference by Similarity to Ideal Solution (TOPSIS) ranking technique is then applied to the Pareto front to obtain an optimal solution. Various passive energy retrofit measures are investigated, and renewable retrofit measures are employed to cover the required energy. This process is repeated for different time frames to consider the impact of climate change on selecting retrofit measures. The results clearly indicate that, for retrofitting a residential NZEB, higher insulation values are needed for future scenarios compared to the present scenario due to the effects of climate change. Using the future scenarios defined by the Shared Socioeconomic Pathways framework, a higher level of envelope insulation and renewable retrofit measures are required to achieve NZEB in the Sustainable Future scenario compared to the Fossil Fuel-dependent Future scenario, with increases of 35% and 50%, respectively.

Experimental study and techno-economic evaluation of an active fault detection kit in the prospect of future zero energy building installations

This article presents an active fault detection kit, applicable to low voltage single-phase electrical installations, in the prospect of the Zero Energy Building concept, integrating on-site renewable energy generation and energy storage. This simple, flexible, self-powered and compact kit is capable of detecting faults, such as power theft (meter tampering), unintentional islanding and neutral conductor loss. Its operation is based on harmonic voltage injection, in series with the electrical installation, through a low-power H-bridge inverter and a current transformer, along with the corresponding harmonic current measurement, to estimate the impedance and effectively detect faulty conditions; the fast and robust Goertzel algorithm is utilized. Moreover, it features IoT communication capabilities, employing the ESP32 microcontroller, to exchange data and information with the installation meters. The functionality and effective fault detection of the proposed device are validated, through experimental tests on a custom-developed hardware prototype; IoT connectivity and data uploading are experimentally tested and verified, too. Finally, a sustainability assessment study is performed, using the Life Cycle Cost Analysis tool.