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Improving the energy efficiency of buildings (IEEBs) is crucial to achieving the European Union's ambitious climate and energy goals. To channel these efforts, new policies, legislation, sources of funding, mechanisms for distributing funds, programs, and support tools are being introduced. The purpose of this study is to demonstrate the effects of the disbursement of EU Cohesion Policy 2014–2020 funds on IEEBs in Poland and Germany, filling the research gap regarding the regional differentiation of investments, beneficiaries, and the spatial distribution of subsidies and projects. An analysis was made of 7818 projects on IEEBs implemented under regional operational programs from European Regional Development Funds under Thematic Objective 4. This research was conducted for two main variables: (1) beneficiaries (8 categories) and (2) investments (8 categories). Based on this division, using a cluster analysis through the use of Ward's agglomerative hierarchical clustering method, groupings were made in relation to beneficiaries (6 groups) and investments (6 group). The results allowed us to identify regional differences and similarities in the approach to the disbursement of funds on IEEBs, to indicate the main beneficiaries, to highlight trends in this regard, to demonstrate the impact of changes in territorial affiliation on investment targeting, and, furthermore, to capture the variation in the sophistication of the implementation of EU IEEB-related policies and legislation. The results provide a well-documented voice in the discussion of the effects of distributing EU funds for IEEBs in the regions of Poland and Germany and provide a basis for further comparative research. [ABSTRACT FROM AUTHOR]

The global construction industry significantly contributes to energy consumption and greenhouse gas emissions, necessitating immediate action for sustainable development. Recognizing the impact of buildings on emissions, the United Nations has set ambitious energy-related goals for 2030. Retrofitting buildings emerges as a strategic method for reducing energy consumption, offering lower environmental impact and life cycle costs. However, retrofitting is a complex process influenced by diverse factors such as policies, available resources, techniques, building-specific data, and uncertainties. Thus, this paper reviews the existing literature on retrofitting strategies for tropical and humid climates to identify effective approaches for enhancing energy efficiency, thermal comfort, and overall building performance in these regions. Through comprehensive analyses, including bibliometric analysis using VOSviewer version 1.6.18 and systematic assessments, this study investigates various retrofitting strategies. This study categorizes tropical climates into Af (Tropical Rainforest Climate) and Aw (Tropical Savanna Climate) based on the Köppen climate classification. It reveals distinct emphases, with Af climates concentrating on office buildings and Aw climates prioritizing residential structures. Passive strategies were predominantly favored in office buildings, with glazing being the most commonly implemented approach. Residential structures, on the other hand, adopted a combination of passive strategies such as phase change materials along with active methods like appliance replacement. Educational buildings tended to rely on passive strategies, including roof covers, shading, and glazing. The absence of specific cost values underscores the importance of establishing baseline metrics, revealing significant challenges in retrofit techniques. This study further highlights an opportunity to explore passive methods in educational buildings, stressing the need for comprehensive guidelines, especially in institutional settings. Moreover, it emphasizes the urgency for ambitious regulations to address carbon emissions and optimize energy efficiency in tropical climates. [ABSTRACT FROM AUTHOR]

A wider deployment of nearly zero energy buildings (NZEBs) is expected to contribute to the transition to a decarbonized and energy-efficient building sector in Europe. This study proposed an integrated energy-economic analysis to exemplify the feasibility of NZEB renovation in temperate climate. A parametric analysis was performed to identify technical building system configurations that give minimum share of renewable energy systems contributing to NZEB level. Final energy savings, global costs and cost-effectiveness of renovating a building to NZEB level are analysed, considering active and passive energy efficiency measures (EEMs). The active EEMs included efficient water taps and heat recovery ventilation, and the passive EEMs encompassed insulations to roof, exterior walls and ground floor, and improvements of windows and doors. The building had initial final energy use of 133 kWh/m2 year for space heating, domestic hot water production (DHW) and facility electricity. The results show that NZEB level is achieved with active and passive EEMs, without renewable energy systems for scenarios with low discount rates and high future energy price escalations. The annual final energy use for space heating, DHW and facility electricity is reduced cost-effectively by 37-54%. Furthermore, increasing size of PV-system enhanced cost-effectiveness by lowering total global costs. [ABSTRACT FROM AUTHOR]

In supporting the phase-out of the fossil fuels, Roof Top Photovoltaic (RTPV) deployment has been adopted worldwide as an important step of a bottom-up driving pathway of citizens’ transformation to become net energy producers within the community of their localized building environment. However, the diverse bioclimatic conditions of this environment may affect the best RTPV implementation. This is facilitated by climate-related characterization and regional adaptation. Hence, the built environment globally as a function of the global horizontal irradiation (GHI), the local environmental parameters of the different climatic zones and the associated technological developments are surveyed.In this work, we have critically assessed the RTPV effect on the building's overall energy performance and found beneficial over a diverse range of moderate and warm climates. By applying adequate insulation beneath the RTPVs, the increased heating needs in winter in cold climates or higher nighttime cooling needs in summertime can be avoided. To design low-energy buildings, we propose an analytical framework based on the space energy coverage by RTPV and the global horizontal irradiation. Moreover, RTPV cooling at elevated temperatures improves the efficiency up to 20 % and increases the generated electricity up to 15 %. Increasing the RTPV efficiency with emerging technologies could extend the decarbonization of high-rise buildings with energy efficiency and RTPV measures. To accelerate the clean energy transition, rooftop PVs should be widely adopted for sustainable solar building applications. Combined with electrical storage, this will allow renewable energy resources to cover a large fraction of future building energy needs worldwide.

This study presents a detailed analysis of thermal comfort and energy consumption in a Passivhaus-certified apartment in Bolueta Tower, Bilbao, Spain, over a period of three years (2020–2022). Utilizing a comprehensive, long-term monitoring approach, the research investigates the effectiveness of the Passivhaus standard in achieving both energy efficiency and occupant comfort in a temperate climate. Using calibrated data loggers to record indoor temperature, humidity, and CO2 levels were used alongside the collection of utility bills to assess energy consumption and thermal comfort, as well as IAQ, against several international standards. Significant issues with overheating were confirmed, in line with previous research. During the warmer months, indoor temperatures frequently exceeded the Passivhaus comfort threshold of 25 °C, reaching as high as 31.3 °C, particularly in the living room and bedroom. This resulted in discomfort during summer, with the percentage of hours above 25 °C reaching 23.21% in 2022. Nighttime temperatures often surpassed 24 °C, impacting sleep quality. Conversely, heating consumption was minimal, corroborating the building's energy efficiency in colder months. The findings highlight a critical gap in the Passivhaus standard when applied in milder climates, where overheating becomes a significant issue. This study suggests the need for an integrated approach in sustainable building design, one that balances energy efficiency with adaptive strategies to mitigate overheating, such as improved natural ventilation and thermal mass. These insights contribute to the ongoing discourse on optimizing energy-efficient buildings for occupant comfort in various climatic conditions. [ABSTRACT FROM AUTHOR]

As buildings are one of the major contributors to greenhouse gas emissions and energy consumption, they have a key potential for energy efficiency and indoor environmental quality improvement. Therefore, the development of nearly Zero-Energy Buildings (nZEBs) is strategic to respond to these challenges and to design and retrofit sustainable highly performing buildings. Actually, the nZEB target can also be reached with highly insulated wooden technologies. However, they must be critically revised and adapted when taking into account the warm climate peculiarities. The paper contributes to this attempt by dealing with the implementation of a methodology specifically focused on the long-term assessment of the real building envelope performance. The methodology is applied to a recently built wooden nZEB detached single-story dwelling constructed in 2017 in central Italy. One year monitoring data were collected about the envelope in-field dynamic performance and the indoor microclimate and well-being conditions. The theoretical design-stage data and the monitored data were compared. The positive aspects as well as the critical issues of nZEB target in the Mediterranean climate context and the performance gap were underlined. Accordingly, the main aspects to be considered in the design of nZEBs envelope were highlighted. [ABSTRACT FROM AUTHOR]

Overheating in buildings is a growing challenge in temperate climates, even in those where the traditional design focus was on protecting from cold and winter energy savings. This paper addresses a collateral problem that arose during the study of overheating in a residential Passivhaus building in Bilbao, northern Spain. Specifically, the local climate of three laundry spaces was investigated, where high daytime and nighttime temperatures were recorded. An extensive monitoring campaign was carried out with different durations up to more than 21,000 h over four years, and the collected data were compared with outdoor climatic conditions. The results allowed for characterizing the thermal behavior of these semi-outdoor spaces and show the magnitude of the problem, quantifying it. Laundry spaces were confirmed to be hotter and dryer than the outdoor climate almost always. The mean average difference between the monitored rooms and the exterior was quantified to be around positive 5 °C during both daytime and nighttime. Extreme heat events were documented, with maximum temperatures above 50 °C and temperature differentials of up to 15.85 °C. In addition, this article comments on the impact of overheating these laundry spaces on the interior of the dwellings, pointing out the differences between the assumptions made during the design phase of the project and the observed or measured reality. Questions were raised about the possible implications of the peculiar performance of these semi-outdoor spaces on the mechanical heat recovery ventilation system (MHRV). The data presented in this article revealed and quantified a design flaw that went unnoticed by all agents involved in the planning, design, and construction of the 361-apartment project. The inability to predict the behavior of the studied spaces has had a negative impact on building performance during the summer months and has prevented the implementation of strategies that could have been beneficial in other periods. A thorough analysis of the thermal behavior of similar spaces becomes essential to prevent performance gaps in future projects and to inform adequate building modeling in the design stages. [ABSTRACT FROM AUTHOR]

Construction and demolition waste constitute more than one-third of the total waste generated in the European Union. The pursuit of sustainable renovation must progress further to encompass elements that ensure reuse or recyclability. A fundamental transformation, involving extensive renovation and a transition to circular renovation practices, is indispensable in effectively addressing the pressing challenge of decarbonization for the entire building stock in Europe. In this study, we have developed a circular deep renovation solution using prefabricated modular external additional insulation elements to achieve a nearly Zero Energy Building (nZEB). Circular prefabricated modular external additional insulation elements were formulated, manufactured, and installed. The potential for disassembly and reutilization of materials was developed and demonstrated for both a prototype and the complete deep renovation. The analysed prefabricated modular solutions exhibited greater potential for circularity compared to the traditional External Thermal Insulation Composite System (ETICS) due to their superior demountability and reusability characteristics. The overall cost of the renovation, which included the installation of a new heating system, replacement of water and sewer pipes, addition of 50 kW photovoltaic (PV) panels on the roof, installation of new balconies, addition of a balanced ventilation system with heat recovery, and replacement of the electricity system in common areas, amounted to 505 €/m². Following the deep renovation, the Energy Performance Value was measured to be 92 kWh/(m²·a), resulting in an EPC class of A. This implies that the building now meets the requirements for nZEB in accordance with Estonian legislation, with no performance gap. [ABSTRACT FROM AUTHOR]

For achieving carbon neutrality, new buildings must be built according to very high-performance standards, such that their energy needs can be covered predominantly by onsite renewables. Although the technical solutions for efficient envelopes are well established, heat pumps together with PV have proven to be a reliable HVAC system, the discussion is ongoing regarding the optimal system concept and design for NZEB. Furthermore, the real performance strongly depends on the design, implementation, commissioning and operation. Given the complexity of building and HVAC with the influence of climate and users, a benchmark for optimal operation requires the combination of monitoring analysis and validated component and system models. Different steps and aspects of the calibration and optimization process are presented. The model, representing a step towards a digital twin, was used to improve the operation and derive guidelines for future optimal NZEB HVAC design, commissioning and operation for maximum primary energy savings. HIGHLIGHTS Integrated simulation-based design, commissioning and optimization of Net-zero energy residential buildings Calibrated component as well as building and HVAC system simulation models Simulation assisted commissioning and optimization leads to relevant energy savings NZE Multi-Apartment Buildings possible with optimized system design and control Monthly evaluation of primary energy highlights the need for reduced winter energy demand [ABSTRACT FROM AUTHOR]

The global construction industry significantly contributes to energy consumption and greenhouse gas emissions, necessitating immediate action for sustainable development. Recognizing the impact of buildings on emissions, the United Nations has set ambitious energy-related goals for 2030. Retrofitting buildings emerges as a strategic method for reducing energy consumption, offering lower environmental impact and life cycle costs. However, retrofitting is a complex process influenced by diverse factors such as policies, available resources, techniques, building-specific data, and uncertainties. Thus, this paper reviews the existing literature on retrofitting strategies for tropical and humid climates to identify effective approaches for enhancing energy efficiency, thermal comfort, and overall building performance in these regions. Through comprehensive analyses, including bibliometric analysis using VOSviewer version 1.6.18 and systematic assessments, this study investigates various retrofitting strategies. This study categorizes tropical climates into Af (Tropical Rainforest Climate) and Aw (Tropical Savanna Climate) based on the Köppen climate classification. It reveals distinct emphases, with Af climates concentrating on office buildings and Aw climates prioritizing residential structures. Passive strategies were predominantly favored in office buildings, with glazing being the most commonly implemented approach. Residential structures, on the other hand, adopted a combination of passive strategies such as phase change materials along with active methods like appliance replacement. Educational buildings tended to rely on passive strategies, including roof covers, shading, and glazing. The absence of specific cost values underscores the importance of establishing baseline metrics, revealing significant challenges in retrofit techniques. This study further highlights an opportunity to explore passive methods in educational buildings, stressing the need for comprehensive guidelines, especially in institutional settings. Moreover, it emphasizes the urgency for ambitious regulations to address carbon emissions and optimize energy efficiency in tropical climates.

The proper operation of the ventilation system under very low external air temperature is still a great challenge. Due to the icing of the ventilation unit, maintaining appropriate air parameters in rooms during the winter period typically requires additional external energy for the devices. In this research work, a unique system with a periodic counterflow heat exchanger was presented. The proposed system characterized by a high efficiency of heat and moisture recovery operates continuously, regardless of the prevailing external weather conditions. An experimental and numerical analysis of the periodic counterflow heat exchanger for air-to-air heat recovery ventilators was carried out to verify and determine the key parameters of the system operation. It has been shown that simple modification of a typical counterflow heat exchanger allows moisture recovery from the extract air. The developed model of the proposed solution allowed for a detailed analysis of the operation of the system depending on weather conditions. As a result of the simulations, the impact of the temperature, velocity, and humidity of fresh and extract air on heat and moisture recovery efficiency was determined.

The emission of greenhouse gases, particularly CO2, is widely recognized globally for its significant impact on the climate worldwide. These gases substantially influence the climate across the globe, thereby increasing the demand for greater energy usage and, consequently, elevating the energy requirements for HVAC (Heating, Ventilation, and Air Conditioning) systems. Additionally, the rise in atmospheric CO2 poses a serious threat to human health and ecosystems, presenting an even greater challenge for thermal comfort. Consequently, there is a growing necessity to study buildings in order to achieve Nearly Zero Energy Buildings (nZEB). This specific study aims to demonstrate the influence of energy consumption on CO2 emission in the environment, utilizing energy sources from district heating/cooling and heat pumps, through simulations conducted using EnergyPlus software. The building subjected to these simulations is a multi-purpose structure primarily used for office purposes, located in Niš, Serbia. [ABSTRACT FROM AUTHOR]

Nearly Zero Energy Buildings (NZEBs) play a key role in the world energy transition. This is motivating the scientific community to develop innovative electrical and thermal systems characterized by very high efficiency to specifically address the energy needs of modern buildings. Naturally, the integration of the latest generation photovoltaic (PV) systems into buildings helps to satisfy this need, and, with this objective in mind, an innovative and highly efficient building-integrated photovoltaic (BIPV) system is presented and discussed in this paper. The proposed PV system is purpose-built to be fully integrated into a variety of buildings (preferably into their rooftops) and assumes the form of a PV skylight. It is based on a certain number of innovative rotating bifacial PV modules, which are specifically made to be installed "under-glass" within a custom-made transparent casing. Thanks to their properties, the PV modules can be rotated using a very low-power, reliable, and efficient mono-axial solar tracking system, fully protected against adverse atmospheric agents. Once the proposed PV skylight is fully integrated into a building, it generates electricity and, additionally, helps to improve both the energy performance and the aesthetic appearance of the building. The electricity generation and illuminance performances of the proposed PV skylight are experimentally tested using a low-power homemade prototype driven by different solar tracking logics and under different operating conditions; the most relevant results are summarized and extensively discussed. The main outcome of the experimental study is that the most effective performance of the PV skylight is obtained by installing, in its available surface, the maximum possible number of rotating bifacial PV modules, side by side and with no empty spaces between them. [ABSTRACT FROM AUTHOR]

This study presents a detailed analysis of thermal comfort and energy consumption in a Passivhaus-certified apartment in Bolueta Tower, Bilbao, Spain, over a period of three years (2020–2022). Utilizing a comprehensive, long-term monitoring approach, the research investigates the effectiveness of the Passivhaus standard in achieving both energy efficiency and occupant comfort in a temperate climate. Using calibrated data loggers to record indoor temperature, humidity, and CO2 levels were used alongside the collection of utility bills to assess energy consumption and thermal comfort, as well as IAQ, against several international standards. Significant issues with overheating were confirmed, in line with previous research. During the warmer months, indoor temperatures frequently exceeded the Passivhaus comfort threshold of 25 °C, reaching as high as 31.3 °C, particularly in the living room and bedroom. This resulted in discomfort during summer, with the percentage of hours above 25 °C reaching 23.21% in 2022. Nighttime temperatures often surpassed 24 °C, impacting sleep quality. Conversely, heating consumption was minimal, corroborating the building’s energy efficiency in colder months. The findings highlight a critical gap in the Passivhaus standard when applied in milder climates, where overheating becomes a significant issue. This study suggests the need for an integrated approach in sustainable building design, one that balances energy efficiency with adaptive strategies to mitigate overheating, such as improved natural ventilation and thermal mass. These insights contribute to the ongoing discourse on optimizing energy-efficient buildings for occupant comfort in various climatic conditions.

As buildings are one of the major contributors to greenhouse gas emissions and energy consumption, they have a key potential for energy efficiency and indoor environmental quality improvement. Therefore, the development of nearly Zero-Energy Buildings (nZEBs) is strategic to respond to these challenges and to design and retrofit sustainable highly performing buildings. Actually, the nZEB target can also be reached with highly insulated wooden technologies. However, they must be critically revised and adapted when taking into account the warm climate peculiarities. The paper contributes to this attempt by dealing with the implementation of a methodology specifically focused on the long-term assessment of the real building envelope performance. The methodology is applied to a recently built wooden nZEB detached single-story dwelling constructed in 2017 in central Italy. One year monitoring data were collected about the envelope in-field dynamic performance and the indoor microclimate and well-being conditions. The theoretical design-stage data and the monitored data were compared. The positive aspects as well as the critical issues of nZEB target in the Mediterranean climate context and the performance gap were underlined. Accordingly, the main aspects to be considered in the design of nZEBs envelope were highlighted.

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The NZEB (Nearly Zero Energy Building) spreading with its reduced energy performance is one of the main purposes of the Directive 2010/31/EU.New buildings design and existing buildings renovation have been the subjects of discussion to trace the way towards achieving a high level of energy performance of the entire European building stock. However, in order to keep long-term optimal results, it is necessary to plan a correct management both of thermal systems and of passive climate control.There is still a small amount of data available about the effectiveness of the measures adopted for energy saving in the new design to demonstrate the maintaining of the performance. Therefore, it could be useful to broaden experimental monitoring campaigns, in order to better address the design choices in the next future.As a contribution to increasing knowledge about the intelligent management of an NZEB, the control systems and operating procedures of thermal plants of a case-study (new single house building) are discussed, based on simulation results and long-term measurements. The control procedures for internal environmental conditions and plant systems, aiming at maintaining both indoor comfort conditions and an efficient management of energy consumption, are described.The analyses quantitatively demonstrate how the correct energy management can significantly reduce the actual consumption, compared to the estimated one. Moreover, the need of the adaptation of the home automation management systems to the actual use of the building is put in evidence.Their smart use in fact guarantees the expected performance, and in some cases can improve it, by tailoring the energy behaviour of the building to the users’ specific needs.In the case study, the energy performance of the building, calculated by means of the national methodology, satisfies the NZEB target. The long term monitoring reveals its potential as a Positive Energy Building (PEB) because it produces more energy than its needs.The important support of these analyses shows that it is useful to get a wider number of case studies in order to expand the knowledge of the effective NZEB energy behaviour and to put in evidence smart choices for obtaining the maximum long-lasting energy performance.

Cities are paying more attention to building energy use and carbon footprint for attaining sustainability. Within this building sector, there is a growing attention toward development and adoption of energy efficient retrofit strategies. Plagued by the lack of efforts in achieving comprehensive energy efficient retrofit solution sets (passive, active, and renewable energy systems), the authors acknowledge the concept of NZEB toward achieving energy efficiency by 2050. Toward this end, a numerical energy simulation modeling is carried out to retrofit an existing French "Puccini house" using 'passive, energy efficient building systems and renewable energy' strategies toward an NZEB target in the Mediterranean climate of Nice. Using Design builder 7.0, the simulated baseline energy model (Case A) is retrofitted through variations in the proposed energy efficient retrofit measures using two case scenarios (Case B: passive retrofit; Case C: energy-efficient building) to achieve NZEB (Case D). Assessing the performance of energy efficient retrofits using % energy reduction, the implementation of a high-performance building envelope is achieved using a thermally insulated external wall (46.82%), upgraded airtightness (20.39%), thermally insulated pitched roof component (33.03%), and high-performance window type—a glazing system (3.35%) with maximized window-to-wall ratio (5.53%). The maximum energy-saving retrofit solutions provide an ambitious reduction in energy consumption by approximately 90% from the baseline. A deep retrofitting of the French house meets the NZEB targets, as it reduces the baseline energy consumption from 194.37 kWh/m2/year to 23.98 kWh/m2/year using both passive and active strategies. The remaining energy demand is met by the integration of on-site PV panels (EUI= −27.71 kWh/m2/year), which achieve an increase in energy production by 15.5%, while returning energy back to the grid (−3.73 kWh/m2/year). Findings of this study serve as a guideline for retrofitting traditional French single-family residences, while contributing toward the NZEB goal. [ABSTRACT FROM AUTHOR]

The work describes the energy and economic simulation of a renewable energy community with a social purpose applied to a residential and commercial new district in Milan, the eight buildings of which are connected to a new generation low temperature district heating and cooling network. The system is designed considering two substations for each building, each one providing heating and cooling load profiles by means of heat pumps, and an energy centre that exploits groundwater to extract and dissipate compensating heat at low temperature. Some roof mounted photovoltaic panels, owned by the district residents, cover the electricity needs resulting from the net metering of the renewable energy community. The members of the energy communities are in fact the multifamily buildings of the district acting as prosumers and some fragile families from the surroundings as simple consumers. The economic profits, represented by the subsidies coming from the diffuse self-consumed shared energy and from sold overproduced electricity, are distributed among the members to guarantee, first of all, an economic help against energy poverty to fragile families, and, secondly, a short pay-back-time for photovoltaics. Therefore, the operational strategy of the district network is optimized to maximize the shared electricity and the relative economic benefit by shifting, when possible, the electricity demand when the solar production is available. Finally, three different profit distribution mechanisms are analysed. The added value of this work is the evaluation, by means of a specific case study analysis, of the feasibility of an electric energy community from an economic as well as a regulatory point of view under current legislation.

A multidisciplinary approach to urban regeneration is crucial when the project of suburban areas provides a functional program that includes the combination of technological, environmental, and social innovation. The Reinventing Cities C40 design contest represents an opportunity for designers to deal with the crossing topics of innovation, sustainability, and circular economy. The project proposals focus on the regeneration of urban areas with specific needs, ranging from the reconstruction of urban ecosystems to the re-weaving of fragile and damaged urbanity, to the promotion of areas devalued by functional empty. The Reinventing Cities C40 framework is supporting worldwide the cities in the renovation process, oriented in developing the abandoned areas with the aim of social, energy, and environmental resilience. The framework promotes the link between the Municipalities, the designers, and the local communities to create innovation on multiple levels, in the design process, in the architectural product, in the validation tools based furthermore on the new contractual definition of business models for social support. The renovation of the Crescenzago area in Milan, Italy, is based on an architectural project that entails an integrated mixed-use system of tower and line buildings ensuring an adequate social and housing mix and connection with the surrounding points of interest and green areas. The architectural project relates to the existing context with a synthesis between macro and micro-urban scale: territory, neighborhood, and the new district. The project moves by the definition of the open spaces that imprints the built ones and defines a direct connection with the green system, which pledges the carbon neutrality of the intervention. The site-specific proposal results from the matrix of strategic and technological transferable solutions that provide solar electricity for 82% of the energy needs and the green capture allows to achieve the zero-carbon goal of the district.

This study presents an approach to simulating building-integrated photovoltaic glazing systems composed of semitransparent organic photovoltaic (ST-OPV) elements. The approach consists of a mathematical cosimulation model based on the energy balance of complex glazing systems, considering heat transfer as conduction, mixed convection, and radiation effects. The cosimulation method is based on a functional mock-up unit (FMU) developed in Python and the building simulation program Domus. This work aims at presenting a cosimulation technique that can be easily applied to building energy simulation tools for the assessment of photovoltaic energy generation in glazing systems. The cosimulation glazing model was verified according to ANSI/ASHRAE Standard 140-2011, and the zone temperature was kept within with a root medium square error (RMSE) of 1.45 °C. The simulated building with an ST-OPV system showed promising results and could be applied to near-zero energy buildings since each 6-m 2 glazing has a power generation of around 77 W, equivalent to 9% of available solar resource. [ABSTRACT FROM AUTHOR]

The intelligent and appropriate regulation of indoor temperatures within heritage buildings is crucial for achieving nearly Zero-Energy Building (nZEB) standards, since the technical improvement of the envelope and the overall shape of heritage buildings should be very limited in order to preserve the buildings' authenticity. Thermal comfort is a very important factor that influences the energy performance of a building and the wellbeing of its end users. The present paper focuses on the development of a dynamic thermal human stress model that aimed to accurately predict the necessary garment insulation within a typical high-inertia heritage building. Two different statistical approaches (a Hoke D6 design and a composite factorial design) were employed for the development of this meta-model adapted to a typical mixed-mode heritage building seeking to obtain nZEB classification. Thermal human stress was modeled through the prediction of the thermal absorptivity (b) in accordance with the updated ASHRAE 55 model. Physically measured indoor climate parameters, outdoor meteorological data, and building operational information were coupled to the subjective sensorial dimensions of the problem with the aim of identifying the necessary garment insulation levels within heritage buildings composed of high-thermal-mass materials (for example, stone, concrete, and ceramic tiles). Our investigation focused on the parameter directly linked to the cold/warm sensations experienced due to clothing insulation: thermal absorptivity (b). In brief, the present paper proposes a third-order regression polynomial model that facilitates the calculation of thermal absorptivity, relying on adaptive thermal comfort concepts. The meta-model was then evaluated using Adrian Bejan's constructal law after conducting entropy analysis. The constructal evaluation of the meta-model revealed the characteristic size of the domain regarding variable thermal absorptivity (b) and identified the necessary evolution of the model in order to increase its forecasting capacity. Thus, the model provided accurate forecasting for thermal absorptivity values greater than 50 Ws−1/2 m−2K and will be developed further to improve its absolute location accuracy for scenarios wherein the thermal absorptivity value is lower than 50 Ws−1/2 m−2K. [ABSTRACT FROM AUTHOR]

The building sector accounts for 40% of the total energy consumed in Europe at annual basis, together with the relevant Greenhouse Gas (GHG) emissions. In order to mitigate these impacts, the concept and establishment of the Nearly Zero Energy Buildings (NZEBs) is under continuous and intensive research. In fact, as the energy used for buildings' operation becomes more efficient, impacts resulting from the buildings' embodied energy become of more importance. Therefore, the selection of building materials and components is of high significance, as these affect the energy performance and potential environmental impacts of the building envelopes. The objective of this study is to perform a preliminary Life Cycle Assessment (LCA) on advanced multifunctional building components, aiming to achieve lower embodied emissions in NZEBs. The advanced components analyzed are composite panels for facade elements of building envelopes, providing thermal efficiency. The design of sustainable building envelope systems is expected to upgrade the overall environmental performance of buildings, including the NZEBs. The findings of this study constitute unambiguous evidence on the need for further research on this topic, as substantial lack of data concerning embodied impacts is presented in literature, adding to the growing discussion on NZEBs at a whole life cycle perspective across Europe. This research has shown that the electricity required from the manufacturing phase of the examined building components is the main contributor to climate change impact and the other environmental categories assessed. Sensitivity analysis that has been performed indicated that the climate change impact is highly depended on the electricity grid energy mix across Europe. Taking into account the current green energy transition by the increase of the renewable energy sources in electricity production, as well as the future upgrade of the manufacturing processes, it is expected that this climate change impact will be mitigated. Finally, the comparison between the CLC thermal insulator and other foam concretes in literature showed that the materials of the building components examined do not present any diversions in terms of environmental impact. [ABSTRACT FROM AUTHOR]

The concept of Positive Energy Districts (PEDs), introduced in the Strategic Energy Technology Plan, is one of the fundamental approaches for a successful, clean and sustainable urbanization by 2025. According to the European Commission, a PED is a set of buildings where the community controls the energy flows and aims at a net positive energy balance over a year by utilizing renewable energy sources. There are a plethora of concepts similar to PEDs, such as Positive Energy Community, Net Zero Energy Neighborhood, Plus Energy Districts, that create a need to establish a structure that can facilitate the definition, development, and precise identification of PEDs. Thus, this paper aims to fill this research gap by comparing these and other related concepts through a critical literature review based on three pillars composing the triangle of sustainability: economic, social and environmental. By doing this, the paper aims to determine the connections between these similar concepts, homogenize the use of terms and avoid the issue of repetitions, which can help draw lessons learnt from other energy‐savings concepts. This study shows how PEDs and Nearly Zero Energy Communities have similar bases, aims and omissions. They diverge in a few key concepts, which can become learning points for PEDs. This article is categorized under:Climate and Environment > Net Zero Planning and DecarbonizationPolicy and Economics > Energy TransitionsHuman and Social Dimensions > Energy and Climate Justice [ABSTRACT FROM AUTHOR]

Buildings are among the main reasons for the deterioration of the world environment as they are responsible for a large percentage of CO2 emissions related to energy. For this reason, it is necessary to find solutions to this problem. This research project consists of constructing the metamodel of an urbanization located in Panama, Herrera province. The classification and systematization of its main elements, using the software DesignBuilder and SysML diagrams, were carried out for its subsequent implementation in an optimization analysis that seeks to approach the NZED standard. The main objectives of the optimization are reducing the energy consumption at the lowest possible price while maintaining or improving thermal comfort. In this study, it was possible to reduce electricity consumption to at least 60% of the original value and about 10% of the renewable energy generation capacity by implementing optimization techniques within the retrofit category related to the envelope of the buildings and the occupant’s behavior.

Office building retrofitting may instigate significant reductions in energy consumption and there is growing recognition that buildings' energy, economic and environmental performances (the 3Es) must be considered in tandem. This study aims at maintaining the 3Es when retrofitting office buildings towards nZEB standards. A simulation-based methodology was designed consisting of three generic building forms describing common office building geometries constructed between 1952 and 1980 in Egypt; linear, square with courtyard and L-shaped. Each accommodated for open, closed and semi-closed office layouts as recommended in architectural manuals, and was oriented in four directions, giving 36 base cases. A combined retrofitting strategy was applied and both base cases and retrofitted cases were simulated in DesignBuilder using Cairo weather data, which was validated indirectly through real measurements using preliminary simulations that retrieved statistical significance. Results were analyzed for each of the 3Es by comparing base cases to post-retrofitting performances. Results revealed that not all retrofitted cases that demonstrate acceptable environmental performance and/or energy-efficiency are cost-optimal. However, the following patterns were deduced. Square courtyard buildings yield superior performances, and L-shapes tend to perform outside acceptable ranges. Closed plans demonstrate superior energy and environmental performance but poorer economic performance. 17 out of 36 retrofitted cases achieved nZEB, illustrating the potential of implementing nZEB in Egypt. This work may be considered prototypical, encouraging a national office building retrofitting process toward nZEB. However, implications extend beyond the national level, as results may be used to support a kick-off retrofitting programme based on basic office building geometries. • A methodology to balance the 3Es for generic office building retrofit is proposed. • Patterns were deduced for building geometry and layout. • Square courtyard cases outperform linear and L-shaped forms in terms of the 3Es. • Closed plans perform well for energy and environment but poorer economically. • This study highlights the potential of achieving nZEB in Egyptian office buildings. [ABSTRACT FROM AUTHOR]

Net/nearly zero energy buildings (NZEBs) are being recognized as a promising solution to improve environmental friendliness and reduce energy consumption in the building sector. Traditionally, the energy systems in NZEBs were sized under deterministic conditions. However, such an approach may introduce a failure in achieving the expected system performance due to the presence of multiple uncertainties. Despite considering uncertain parameters in some reported studies, the correlations among uncertainties were often neglected. To maximize the benefits of using NZEBs, an uncertainty-based optimization method is proposed in this study to size energy systems. The correlations among uncertainties are tackled using the copula theory. Additionally, a novel scenario reduction technique to address the correlated uncertainties is introduced to decrease the computational cost. The NSGA-II, coupled with TOPSIS and Shannon entropy, is utilized to formulate and solve the multi-objective optimization problem. The results from simulation analysis validated the robustness and reliability of the designed systems under uncertainties, with the average values of annual thermal discomfort, self-consumption ratio, self-sufficiency ratio, and net interaction level of 8.6 h, 73.0%, 75.5%, and 38.0%, respectively. This approach could be extended and adapted to facilitate the optimal design of multiple energy systems in NZEBs. • Developed an uncertainty correlation-based optimization method for energy systems • Considered correlations among uncertainties to generate more realistic scenarios • Incorporated both probability similarity and correlation loss in scenario reduction • Effectively achieved the predefined multi-objectives of NZEBs under uncertainties [ABSTRACT FROM AUTHOR]

Nearly Zero Energy Buildings (NZEBs) play a key role in the world energy transition. This is motivating the scientific community to develop innovative electrical and thermal systems characterized by very high efficiency to specifically address the energy needs of modern buildings. Naturally, the integration of the latest generation photovoltaic (PV) systems into buildings helps to satisfy this need, and, with this objective in mind, an innovative and highly efficient building-integrated photovoltaic (BIPV) system is presented and discussed in this paper. The proposed PV system is purpose-built to be fully integrated into a variety of buildings (preferably into their rooftops) and assumes the form of a PV skylight. It is based on a certain number of innovative rotating bifacial PV modules, which are specifically made to be installed “under-glass” within a custom-made transparent casing. Thanks to their properties, the PV modules can be rotated using a very low-power, reliable, and efficient mono-axial solar tracking system, fully protected against adverse atmospheric agents. Once the proposed PV skylight is fully integrated into a building, it generates electricity and, additionally, helps to improve both the energy performance and the aesthetic appearance of the building. The electricity generation and illuminance performances of the proposed PV skylight are experimentally tested using a low-power homemade prototype driven by different solar tracking logics and under different operating conditions; the most relevant results are summarized and extensively discussed. The main outcome of the experimental study is that the most effective performance of the PV skylight is obtained by installing, in its available surface, the maximum possible number of rotating bifacial PV modules, side by side and with no empty spaces between them.

The nZEB objectives have raised the standard of building performance and changed the way in which buildings are designed and used. Although energy dynamic simulation tools are potentially the most suitable way for accurately evaluating and forecasting the thermal performance, they need several data inputs and user's knowledge that can affect the reliability of the results. It is precisely these two aspects that proved to be particularly critical, since the reliability of the ICT calculation tools has been widely proven in recent time.However, in order to foster credibility in sustainable architecture, bridging the gap between predicted and measured performance is pivotal to boost the building market towards energy efficiency and provide reliable data to inhabitant, investors and policy maker.The present research aims to identify and quantify the main factors that affect the energy performance gap through a detailed energy analysis carried out on a case study, which can be considered one of the first nearly zero energy residential complex built in Italy. Based on the analysis, the study identifies the main causes of the deviation between the calculated and measured data and demonstrates how it is possible to achieve very reliable models and, therefore, real buildings.Although the procedure traces a classic model calibration scheme, actually it consists of a verification of possible downstream errors mainly due to human factors, such as the provision of incorrect technical data or inappropriate operation.Some observations on the technical, management and regulatory gaps that may generate these errors are reported at the end of the study, together with practical suggestions that can provide effective solutions.

The integration of renewable energy systems in buildings has become a common practice. The design of net Zero Energy Buildings promotes the energy transition from fossil fuels based technologies by coupling renewable systems as photovoltaic (PV) plants with heat pumps for heating and cooling. In this framework, the correct sizing of PV plants plays a central role in the perspective of the definition of self-consumption schemes. Considering the problems related to small-scale photovoltaic plants, the present paper proposes an analysis of different sizing strategies on the energy streams between the building and the electrical grid to reduce the bidirectional energy flows with the electrical grid. The design objective concern the minimization of both the energy exported and imported through an optimized size of the PV plant and the integration of electrochemical energy storage. The investigation is based on the experimental data under real operating conditions obtained from two different residential buildings, a conventional residential house, and a nearly Zero Energy Building (nZEB). The paper aims to discuss the results of the monitoring activity and define criteria and guidelines for the design of this kind of systems based on real collected data. The use of two different self-consumption indexes helps to determine how close the system is to a zero-energy configuration showing that the use of a small to medium size storage system is fundamental for maximizing the self-consumption share of the energy produced.

In 2010, the Energy Performance of Buildings Directive announced that all new buildings are to be nearly zero-energy as of January 2021. Having reached year 2022, it can be said that the transition has proven to be slower than anticipated. Transition research has long acknowledged the potential impact of the human factor in the process of change. While there is a relative wealth of literature on end-users and their perceptions as recipients of change within the demand end of the market, research on professionals and their perceptions as actors in the process of change is limited. Thus, this study looks at the human factor in the supply end of the market by bringing professionals' perceptions to the forefront in its investigation of barriers to the implementation and uptake of nearly zero-energy housing in practice. As part of the project entitled Housing 4.0 Energy: Affordable and Sustainable Housing through Digitization, data were collected through a focus group and semi-structured interviews with housing professionals in Kilkenny, Ireland. Descriptive coding, inferential coding, and fact tracing revealed several identified barriers to be perceptions and not actual barriers to nearly zero-energy housing. Additionally, information dissemination and assimilation between policy and industry was identified as an overarching barrier. Therefore, the paper ends with recommendations to reduce delay factors at the supply end of the market, thus contributing to closing the gap between the development of policies and their implementation. [ABSTRACT FROM AUTHOR]

The energy needs of a Net Zero Energy Building (NZEB) are fully met by renewable energy sources. Nevertheless, the time span of the energy balance can affect the effective energy self-sufficiency of the building. The aim of this paper is to demonstrate the lack of reliability that a yearly energy balance has in characterizing an NZEB. At this scope, comparisons between two different photovoltaic systems (fixed and tracking) and two kinds of energy balance (yearly and monthly) are made for a real NZEB building located in South-Italy. The investigation was carried out through dynamic energy simulations after validating the building model. The results show that the PV surface which attains the NZEB target on yearly basis not always achieves the same objective as the monthly balance. Furthermore, considering a monthly balance, the size of the photovoltaic system with biaxial solar tracking is 50% minor than the fixed one, thanks to a steadier energy production. Also, solar tracking systems show a significantly lower reduction of operational and embodied CO 2 emissions. A final technical-economic analysis shows, however, that design solutions that satisfy NZEB target not always can meet the financial interest of the private stakeholder, showing a high discounted payback period. • The energy needs of an existing NZEB are evaluated through dynamic simulation. • Fixed and tracking PV systems are designed and compared to obtain the NZEB target. • Comparisons between yearly and monthly balance using different PV systems are made. • Yearly balance is not adequate to characterize energy self-sufficiency for an NZEB. • Tracking PVs reduce monthly withdrawal from electricity grid and CO 2 emissions. [ABSTRACT FROM AUTHOR]