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New testing lab of the Institute for Steel Construction at RWTH Aachen University As a well‐established institution with diverse research areas, the Institute of Steel Construction at RWTH Aachen University has a high demand for experimental testing facilities. As a result, a new test hall is under construction since 2023 in the immediate vicinity of the existing research infrastructure. The building envelope has been used to realise a wide range of possibilities for lightweight metal construction with innovative constructions. In addition, parts of the building envelope can be integrated into future research projects as a real laboratory. The synergy effect of the creation of research areas in combination with the building structures as a real research object enables an expansion of the research spectrum at the Institute for Steel Construction at RWTH Aachen University. The unique opportunity to accompany the construction project with innovative digitalisation tools was taken as early as the planning phase. By capturing and measuring the new building during the actual construction process using 3D laser scanning and photogrammetry by drone, it was possible to digitally model the real building structures. These models are integrated into a mixed reality system for assembling parts of the façade, allowing the aluminium panels to be installed with virtual instructions. Both the construction and the use of the new building will expand future research opportunities at the Institute of Steel Construction at RWTH Aachen University. [ABSTRACT FROM AUTHOR]

Refurbishment of steel liner tray constructions The refurbishment of steel liner tray walls in existing buildings has considerable potential for energy savings. This multi‐shell construction method often used in non‐residential buildings, consisting of room‐enclosing liner trays filled with insulation and an outer shell, does not meet today's requirements for the thermal quality of building envelopes. In addition to the complete replacement of the entire wall structure, this article presents two refurbishment options that allow the existing liner trays to be retained, thereby maintaining the ongoing operation of the building. One is the refurbishment using steel sandwich elements, while another is a multi‐part spacer construction with an additional layer of insulation. The presented investigations show that both options enable a significant reduction of the thermal transfer coefficients of the wall construction and thus an improvement in thermal quality of the building envelope. The structural requirements in accordance with the current technical building regulations must also be considered for the refurbishment. In addition to modified wind load assumptions, a sufficient stabilisation of the liner trays and the transfer of vertical loads from the dead weight of the additional construction must be taken into account. [ABSTRACT FROM AUTHOR]

Metal building envelopes in seismic areas Building envelopes in lightweight metal construction, such as sandwich panels or multi‐shell constructions with trapezoidal profiles, are frequently used in industrial and commercial construction. These initially only have a space‐enclosing effect and are dimensioned according to the loads resulting from wind and temperature effects or snow loads. As part of an IGF/FOSTA research project, the aim was to determine the extent to which the roof and wall elements fulfil a stiffening function in the event of an earthquake. To this end, roof and wall elements and their connections to the substructure were examined with regard to their cyclical behaviour, energy dissipation capacity and functionality after seismic events. Detailed tests were carried out on connections, large‐scale tests on shear bays and building physics investigations. [ABSTRACT FROM AUTHOR]

The thermally anisotropic building envelope (TABE) is an active building envelope that redistributes thermal loads in response to weather conditions and building energy demand. Conductive layers throughout the TABE distribute low-grade heat among hydronic loops, altering heat flow direction and intensity. Finite element models of TABE roof and wall panels were developed and calibrated using field evaluation data. The calibration results showed that heat flux differences between the experimental data and finite element models averaged −0.42% and 3.57%, with a maximum mean square error of 1.78 and 3.96 for roof and wall panels, respectively. A reduction in heat flux from the environment to the building living space over the entire testing period (weeks in July/August) was found to be 85% for roof panels and 335% (load reversed) for wall panels. These results indicate TABE can effectively harness low-grade thermal energy sources to achieve high energy efficiency and promote demand-side management. [ABSTRACT FROM AUTHOR]

Accurately measuring the actual building performance would be a significant step toward performance contracting. Methods under occupancy have operational advantages but come with additional constraints due to the variability of weather and occupancy conditions, which cannot be overlooked. Especially in recent, well-insulated buildings, since solar gains are a larger contribution to the global heat balance. This work aims to enhance the accuracy of the Heat Transfer Coefficient estimation in an occupied building by taking better account of solar gains in multilinear regression models. The approach adopted here considers solar gains from both the incident solar heat flux through glazing and from the opaque elements of a building by calculating an equivalent outdoor temperature. This model feeds a multilinear regression model whose parameters are estimated by Bayesian inference. Our model for estimating HTC is validated against a set of virtual data from a simulated detached house under different weather conditions. [ABSTRACT FROM AUTHOR]

The climate-adaptive net-zero energy building design is an effective trend for achieving a carbon-neutral environment and reducing global energy demand, especially, in India where building energy consumption recorded substantial growth in the past decade. This review article focuses on the development of net-zero energy buildings in tropical climates through the analysis of 44 real case studies. This study investigates the building envelope parameters, advance technologies, and their effectiveness on the building energy models. In the first phase of this study, fourteen net-zero energy buildings or high-performance buildings in the USA, China, and India considering energy-efficient design features and their significant effect on energy consumption have been examined. Moreover, the role of building simulation tools in improving energy efficiency is discussed. The second phase investigates the thirty best practices of net-zero energy buildings in tropical climates worldwide based on envelope choices, heating, cooling, and lighting features. Furthermore, this review discusses the evolving definitions, challenges, and inconsistencies in terminologies of net-zero energy building and illustrates India's initiatives towards net-zero development. The objectives of this review study are to highlight the challenges in building material research, advanced lighting, heating, ventilation, and air conditioning technologies, and integration of renewable energy compared to developed nations. Additionally, the gaps that are the barriers to the development of net-zero energy building in India have been identified. The review eventually concludes by providing policy recommendations and suggesting areas for future research to facilitate net-zero energy-building development in India. [ABSTRACT FROM AUTHOR]

This paper explores the minimum energy that would be required to provide all energy-using services currently used the U.S. office building sector if they were all provided by thermodynamically ideal devices that do not violate physical law. Data from the U.S. DOE and the General Services Administration were used to identify office building workspace services, equipment, occupancy and schedules. Internal building loads were estimated after identifying or conservatively approximating the thermodynamically ideal power required for each service. The average thermodynamically ideal office building in the U.S. would use 2.2 kWh/m2-yr or less, which represents 1.0% of the current average end-use consumption in the sector. Such a large gap between the thermodynamic limit and today’s practice is related to the fact that the energy performance of all the internal gain producing equipment in buildings is far from ideal along with the HVAC equipment and envelope components. Ideal office buildings would use 69.7% of their energy for cooking and related domestic water heating and cooling; illumination accounts for a smaller portion, consuming 17.5%, while office equipment and cooling would use 6.9% and 5.9% of the total consumption, respectively. Dramatic reductions come from the elimination of heating energy and air distribution energy brought about by ideal adiabatic building envelopes and frictionless air distribution. Cooling energy is virtually eliminated by the combination of greatly reduced cooling loads and ideal Carnot equipment. But the thermodynamically ideal office equipment would use two orders of magnitude less energy than today as well. [ABSTRACT FROM AUTHOR]

Enhancing the energy efficiency and climate resilience of existing buildings is crucial amid growing environmental challenges. While extensive research has focused on non-residential buildings, studies on thermo-hygrometric conditions in warehouse-type buildings, particularly in subtropical climates, remain limited. This study investigated the impact of building envelope deficiencies on indoor thermal and moisture regulation at the Nori Distribution Center. Using infrared thermal imaging and long-term environmental monitoring, significant thermo-hygrometric fluctuations were identified, primarily due to design and construction deficiencies. Poor insulation, inadequate sealing, and the lack of moisture barriers contributed to unstable indoor temperature and humidity. Seasonal analysis showed that during summer, the median second-floor air temperature reached 28.8 °C, peaking at 39.2 °C, with relative humidity exceeding 70% for 45% of the time. First-floor relative humidity surpassed 70% for 72% of the time. While condensation risk remains low year-round, it increases significantly with air infiltration through gaps in the building envelope. This study recommends enhancing the sealing of the building envelope, upgrading insulation materials and moisture barriers, particularly in the roof, and optimizing the HVAC system to improve energy efficiency and storage conditions. These findings offer valuable recommendations for retrofitting warehouse-type buildings in subtropical climates to improve energy efficiency and climate resilience. [ABSTRACT FROM AUTHOR]

The paper deals with the application of microalgae in building's façade, regard to the broader project comprising the aspects of the environmental comfort of academic spaces and the energy consumption with on-grid photovoltaic generation, as well as the investigation of alternatives for the improvement of the performance of the building envelopes. Thus, its main objective is the application of interdisciplinary concepts involving Architecture and Biotechnology, as known by Black Ecologies, referring to an investigative interest to explore a new approach of nature, not only related to architectural space, but an emergent environmental focus. This relationship is performed by using photobioreactors with microalgae, installed on the façades of buildings for educational use. The present work presents the methodological outline of the research, based on literature review and case studies; complementary experimental methodologies are also presented to contextualize the subject and its application and feasibility. The current state of art showed an emergent approach in terms of international level, but in the Brazilian context any further research was identified yet. In addition to thermal and energy performance, the strategies will allow the process of sequestration of carbon dioxide and other GHG (greenhouse gases) that impacts on the process of climate change and can contribute to reach the sustainable development. This subject coincides with the discussions of the 2050 scenarios and emission reduction, which were faced at the recent COP-27 and its connections with an integrative way to contribute to the United Nations Sustainable Development Goals. [ABSTRACT FROM AUTHOR]

Residential buildings consume approximately 36% of total electricity consumption in Cyprus and this is expected to continue increasing in the coming years. This study explores the potential for energy savings in residential buildings in Cyprus through optimising building envelopes and insulation materials. Using building information modelling and energy modelling software, the study analyses 120 combinations of building envelopes and eight insulation materials, identifying an optimal combination of wall, roof, and flooring materials that could result in 32% energy load reductions and 27% lower life-cycle costs compared to the median scenario. High-density rock wool insulation on roofs and double-glazed windows were also found to offer both monetary and energy performance benefits. A sensitivity analysis revealed that the current high energy prices could provide greater economic incentives to adopt these optimisation strategies. Optimising building materials in Cyprus could play a critical role in climate strategy while also offering significant economic benefits. [ABSTRACT FROM AUTHOR]

This article emphasizes the significance of understanding the actual thermal properties of thermal insulation materials, which are crucial for avoiding errors in building design and estimating heat losses within the energy balance. The aim of this study was to analyse the thermal parameters of selected thermal insulation materials, particularly in the context of their stability after a period of storage under specific conditions. The materials chosen for this study include commonly used construction insulations such as polystyrene and mineral wool, as well as modern options like rigid foam composites. Experimental studies were conducted, including the determination of the thermal conductivity coefficient λ, as well as numerical analyses and analytical calculations of heat flow through a double-layer external wall with a window. The numerical analyses were performed using the TRISCO software version 12.0w, based on the finite element method (FEM). A macrostructural analysis of the investigated materials was also performed. The findings indicated that improper storage conditions adversely affect the thermal properties of insulation materials. Specifically, storing materials outdoors led to a deterioration in insulating properties, with an average reduction of about 4% for the standard materials and as much as 19% for the tested composite material. Insufficient understanding of the true thermal properties of insulation materials can result in incorrect insulation layer thickness, degrading the fundamental thermal parameters of external walls. This, in turn, increases heat loss through major building surfaces, raises heating costs, and indirectly contributes to greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Wind-driven rain (WDR) constitutes a significant source of moisture for building facades, which poses considerable challenges to both the thermal insulation performance and long-term durability of walls. Prior studies have contributed significantly to the understanding of fluid behavior and moisture response of WDR upon impacting walls. However, the quantification of absorbed rainwater by the wall remains elusive. To address this gap, this study focuses on comprehending the dynamic WDR absorption behavior of various exterior finishing materials. Specifically, nine types of finishing materials were selected as research objects and conducted field measurements. The findings reveal that WDR absorption ratio is influenced by physical parameters of materials, surface waterproofing and the cumulative WDR. Leveraging multiple regression fittings, we established an empirical WDR absorption ratio calculation mode. This model serves as a valuable reference for determining building simulation parameters regarding dynamic moisture boundary conditions on the exterior surfaces of walls. By providing empirical insights into WDR absorption, our research contributes to a more comprehensive understanding of moisture behavior in building envelopes, thereby aiding in the development of effective strategies for enhancing building performance and durability. [ABSTRACT FROM AUTHOR]

Energy crises are becoming a problem for the globe. Most of the energy being produced is utilized in buildings. Building design and materials that are used in buildings play a vital role in saving electricity. Sustainable cities are one of the eleventh goal of Sustainable Development Goals to be achieved and this study is in context of SDGs for developing tools to create this globe sustainable and efficient society for humans. Phase change material is a type of material that can absorb and release heat energy as it changes between solid and liquid states. This ability to store and release thermal energy makes phase change materials a promising material for use in building insulation, Heating Ventilation Air Conditioning Systems, and other energy-efficient applications. The use of PCM in buildings has the potential to significantly reduce energy consumption and improve thermal comfort levels. By incorporating PCM into building envelopes, such as walls, roofs, and floors, the material can absorb excess heat during the day and release it at night, helping to regulate indoor temperatures and reduce the need for heating and cooling systems. This study investigates the impact of using PCM in building envelopes. In this regard, office building rooms are modelled in computer-aided design software and are simulated in energy plus software. The simulation results are validated by considering the experiment and numerical study as a reference from the paper. The model room is simulated for Hyderabad, Pakistan. Building envelopes without PCM have a conduction rate of around 106.6 W/m2, whereas building envelopes with PCM have a conduction rate of around 42 W/m2. This shows that utilization of PCM reduced heat conduction up to around 40%. PCM reduced energy consumption by around 33.25 kWh/year/m2. Results show that without PCM air temperature was above the thermal comfort value. it reached 300C in hot months, it reduced up to 270C with the incorporation of Phase Change Material. [ABSTRACT FROM AUTHOR]

The prevalence of small-scale structures, such as sentry buildings, has become widespread, with many of these buildings exposed to the outdoor environment and exhibiting suboptimal thermal insulation in their envelopes. Through a comprehensive study of outdoor disturbances, the most unfavourable envelope was identified. In light of this finding, we have designed static air layer sentry buildings (SAL-SB) and dynamic air layer sentry buildings (DAL-SB). The study conducted experiments and numerical simulations to evaluate the impact of air layer thickness, vent opening forms, and inlet velocities on the thermal insulation of sentry buildings. The results showed that both the SAL and DAL effectively improved thermal insulation, and a thickness of 25 cm has been found to offer the best thermal insulation. However, considering the balance between thermal insulation and cost-effectiveness, a thickness of 15 cm is recommended. Additionally, for DAL, an inlet velocity of 3 m/s is the threshold for switching the heat transfer direction on the roof. These findings provide novel insights into enhancing the thermal environment. [ABSTRACT FROM AUTHOR]

Improving the energy efficiency of buildings is an important element of the effort to address global warming. The thermal performance of building envelopes is the most important thermal and physical property affecting energy performance. Therefore, identifying the thermal performance of a building envelope is essential to applying effective energy-saving measures. The U-value is a quantitative indicator of the thermal performance of the building envelope quantitatively. Methods for determining the U-value are largely classified into passive methods, which use building information without measurement campaigns, and active methods, which conduct in situ measurements. This paper reviews and evaluates the most commonly used methods and experimental results of previous studies to determine the actual U-value of a building envelope. Accordingly, this paper focuses solely on field measurement studies, excluding laboratory measurements. Comparing the existing methods used to determine the U-value can help researchers choose appropriate field measurement methods and future research directions. [ABSTRACT FROM AUTHOR]

The global drive for sustainable development and carbon neutrality has heightened the need for energy-efficient buildings. Photovoltaic buildings, which aim to reduce energy consumption and carbon emissions, play a crucial role in this effort. However, the potential of the building envelope for electricity generation is often underutilized. This study introduces an efficient hybrid method that integrates Particle Swarm Optimization (PSO), Support Vector Machine (SVM), Non-dominated Sorting Genetic Algorithm II (NSGA-II), and the weighted Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method. This integrated approach was used to optimize the external envelope structure and photovoltaic components, leading to significant reductions: overall energy consumption decreased by 41% (from 105 kWh/m2 to 63 kWh/m2), carbon emissions by 34% (from 13,307 tCO2eq to 8817 tCO2eq), and retrofit and operating costs by 20% (from CNY 13.12 million to CNY 10.53 million) over a 25-year period. Sensitivity analysis further revealed that the window-to-wall ratio and photovoltaic windows play crucial roles in these outcomes, highlighting their potential to enhance building energy performance. These results confirm the feasibility of achieving substantial energy savings and emission reductions through this optimized design approach. [ABSTRACT FROM AUTHOR]

There are many different factors affecting indoor air quality: environmental ones such as temperature, humidity, human activities within the building, smoking, cooking, and cleaning, but also external pollutants such as particulate matter, biological contaminants, and viruses or allergens. This study investigated the indoor air quality (IAQ) of a primary-school classroom in Cracow, Poland, based only on CO2 concentration levels exhaled by occupants. In the 1960s, over a thousand schools were built in Poland using similar technology. Most of them are still in use, and in many cases, modernization works are being carried out to improve their building envelope and the comfort of their use. The analyzed school is one of several hundred similar ones in southern Poland. Therefore, analyzing the possibilities of improving IAQ is an important topic, and the results can be used in the modernization process for many other buildings. Measurements indicated that the CO2 levels significantly exceeded acceptable standards, signaling poor air quality during usage time. This problem was connected mainly with the low efficiency of the natural ventilation system being used in the classroom. It is worth emphasizing that this type of ventilation system is the most commonly used ventilation solution in Polish schools. To address this problem, the classroom environment was simulated using CONTAM software, and the model was validated by comparing the simulated measurement data against the collected measurement data. Next, simulations for the entire heating season in Cracow were conducted, revealing that the IAQ remained consistently poor throughout this period. These findings highlight the persistent problem of inadequate ventilation in the classroom, which can have adverse effects on the health and performance of students and teachers. This article shows the usefulness of CONTAM for modeling not only gravity ventilation but also the window-opening process. The validated CONTAM model will be subsequently utilized to simulate annual IAQ conditions under various ventilation strategies in order to identify the most effective methods for maintaining acceptable IAQ while minimizing energy consumption. In our future analysis, the validated model will be used to test the following systems: demand-controlled ventilation (DCV), exhaust ventilation, and DCV/balanced ventilation with heat recovery. [ABSTRACT FROM AUTHOR]

Insulating glass units (IGUs) are the most common filling for external building envelopes. These elements have many advantages related to the thermal protection of buildings. However, some climatic loads are generated or modified due to the sealed gas cavity between the glass panes. The gas enclosed in the cavities changes its parameters under external load, which affects the operational deflection and stress in an IGU. In most computational models describing this phenomenon, the component panes are assumed to be simply supported on the edge spacer, which is considered a sufficient approximation. This article, which continues previous work, assumes that the component glass panes can be supported elastically at the edges. The parameter describing this connection is rotational stiffness. Based on the theory of linear–elastic plates, coefficients were determined to calculate the change in cavity volume, deflection, and stress in glass panes. Then, the results of calculations of the influence of rotational stiffness and static values in exemplary IGUs of various structures, loaded with changes in atmospheric pressure and wind, are presented. It was found that a feedback loop occurs here. The deflection and stress in elastically supported single panes are lower than in the case of those simply supported. However, the lower susceptibility to deflection of the component panes weakens the gas interaction in the cavity, and the resultant load on these panes increases. The influence of rotational stiffness on the resulting static values may therefore vary. In the analyzed examples, this influence was primarily negative for symmetrical loads and clearly positive for wind loads. [ABSTRACT FROM AUTHOR]

A supermarket made of infra‐lightweight concrete – Proof of stability for a fire wall Infra‐lightweight concrete (ILC) is a special form of lightweight concrete which, due to its low density, possesses improved thermal insulation properties in comparison to normal concrete. ILC facilitates the construction of monolithic, single‐layer building skins without any added thermal insulation or facade cladding. This way, the building components are effectively simplified in comparison to conventionally insulated concrete members and the recyclability is significantly improved. In addition to that, structural elements made of ILC have a reduced CO2 footprint in comparison to conventional composite elements of the building envelope. After 15 years of research and several completed construction projects in the housing and education sector, a commercial retail building has been realized. For this project, an individual approval for a firewall built out of ILC was obtained based on a fire test in combination with a transfer concept based on calculations. This article demonstrates the transfer concept as well as a simplified structural analysis concept for the proof of stability developed for the special application of a firewall. [ABSTRACT FROM AUTHOR]

Based on the coupling characteristics of photovoltaic power generation and phase change heat storage, a photovoltaic phase change composite building envelope structure was proposed and the effect of phase change heat storage on the performance of the composite building envelope was further analyzed. Firstly, the heat flow transfer model of photovoltaic phase change composite envelope structure was constructed, and then the influence of phase change layer structure position, phase change temperature and phase change thickness on its power generation capacity and thermal insulation effect was explored. On this basis, by comparing the thermal characteristics of traditional envelope structure and composite envelope structure, the indoor environmental load regulation and energy saving potential of composite envelope structure were expounded. The research shows that the phase change heat storage has a great influence on the power generation and thermal insulation performance of the photovoltaic phase change composite envelope structure. The closer the phase change material is to the room, the better the thermal insulation effect is; and the indoor temperature shows a tendency to approach the phase change temperature. The phase change material close to the photovoltaic panel means that the heat can be stored more fully, and the photovoltaic power generation is higher. When the phase change material is close to the photovoltaic panel, the power generation is 1 263.06 J, which is significantly improved compared with the photovoltaic envelope structure. At the same time, when the thickness of the phase change material is 40 mm, the power generation reaches the maximum value, which is 0.55% higher than the working condition of 10 mm. In addition, within one operating cycle, the photovoltaic phase change composite envelope structure significantly reduces the building's cooling load, showing good heat insulation and energy saving effects. [ABSTRACT FROM AUTHOR]

A solution for solar photovoltaic evaporative cooling and ventilation cavities was proposed to address the bottleneck problems faced by photovoltaic modules in the application of building envelope structures, such as increased working temperature and reduced power generation efficiency caused by photovoltaic module heat generation, as well as their potential impact on building cooling and heating loads. This solution involved installing photovoltaic cells on the surface of the building envelope and keeping a certain distance from the building wall to form a ventilation cavity. At the same time, an evaporative cooling device was arranged on one side of the back panel of the photovoltaic cells. By setting up an outdoor test platform and conducting controlled experiments, the impact of the evaporative cooling effect on the thermal and moisture performance of each component of the solar photovoltaic ventilation cavity and the changes in its electrical properties were studied. Experimental results show that the ventilation cavity with evaporative cooling has a significant cooling effect on the photovoltaic front, photovoltaic backplane, cavity backplane and cavity interior. Compared with the ventilation cavity without evaporative cooling, the average temperatures of these parts are reduced by approximately 3. 7, 7. 6, 4. 5, and 3. 9 ℃, respectively, with the percentage reductions being 10. 2%, 20. 8%, 13. 6%, and 11. 9% respectively. At the same time, the all-day average electrical power of the ventilation cavity with evaporative cooling is improved by approximately 15. 9% compared to the ventilation cavity without evaporative cooling. These experimental data verify the effectiveness of evaporative cooling technology in reducing the operating temperature of photovoltaic modules and improving the power generation efficiency of photovoltaic modules, and provide data support for the further application of photovoltaic building integration. [ABSTRACT FROM AUTHOR]

Residential buildings are one of the prime candidates in the United States for reducing energy consumption. Continuous exterior insulation (CEI) is being used increasingly often in residential buildings to improve energy efficiency. Windows constitute 15–40% of a building envelope and are the weakest component in energy performance. The installation of windows in walls with CEI has not been well evaluated. We identified four cases of installing windows in walls with CEI of 25–76 mm (1–3 in.) thickness and analyzed the energy loss between the window and wall interface (flanking loss), structural issues, air leakage, and moisture penetration. Thermal analysis showed that the insulation value (RSI) of the 305 mm (12 in.) perimeter wall surrounding a window decreased by 7.6–34.5% in the four cases when compared with the RSI of the wall without the window. A window installation method is proposed to address the issues likely to occur with installation methods currently being used in the field. An out-of-the-box installation system was also designed to achieve a better thermal performance, cost effectiveness, and structural performance in high-performance residential buildings. [ABSTRACT FROM AUTHOR]

The performance and durability of wood-frame building envelopes is affected by long-term moisture transport and its impact. Despite considerable progress in deterministic and prescriptive methodologies aimed at estimating moisture deposition and the consequent risk of mold growth, a consensus in methodology applicable to the analysis of moisture risk in building enclosures is an unfinished agenda. This might partly be caused by uncertainties that exist due to variations in input parameters, model structure, and data scarcity. To address this issue, this study presents a probabilistic risk assessment of building envelope deterioration from moisture accumulation. The proposed methodology integrates the development of meta-models, a full-factorial response surface methodology, and Bayesian analysis. The effectiveness of the proposed approach is demonstrated through a parametric analysis of typical wall assemblies featuring diverse layers and boundary conditions. The findings highlight the influence of input variables and their relative significance on moisture accumulation in the selected climate zones. Additionally, a sensitivity analysis of model parameters and the application of Bayesian analysis in specific contexts are presented, facilitating comparative evaluation of moisture-related risk of building envelopes. [ABSTRACT FROM AUTHOR]

Energy efficiency in the context of building design is a significant concern in Morocco. This paper offers a comprehensive analysis of how various design variables can impact both energy consumption and thermal comfort in the Moroccan context. Rather than isolating individual design variables, we investigate synergistic combinations of these variables. To achieve this, we develop multiple building design scenarios, each employing different combinations of design options, focusing on building orientation, window-to-wall ratio, building envelope construction, and window shading. We use EnergyPlus to conduct energy simulations for all scenarios under the hypothesis of air-conditioned houses and free-running houses with and without natural ventilation. Our results reveal that building design has the potential to significantly enhance energy efficiency and thermal comfort, but not for the same design strategies. In comparison to the most energy-efficient design scenario, the least favorable design scenario can lead to an increase in energy consumption between 237% in Agadir and 130% in Ifrane. Meanwhile, design scenarios favoring comfort can increase the number of comfortable hours by 85% in Agadir and 59% in Ifrane. We identify optimal building design scenarios that simultaneously offer the highest comfort levels with the lowest energy requirements. The findings provide valuable guidance for architects, allowing them to design high-performance buildings in all climate zones in Morocco. [ABSTRACT FROM AUTHOR]

This paper addresses the research gap concerning the impact of thermal diffusivity on cooling energy consumption in buildings, specifically in the context of Saudi Arabia's hot climate. The objective is to determine the optimal thermal diffusivity of building walls for different climate conditions in Saudi Arabia to minimize the cooling energy consumption of residential buildings. The study analyzes four locations in Saudi Arabia, namely, Riyadh, Jeddah, Abha, and Tabuk, to understand the correlation between optimal thermal diffusivity and cooling degree days. The study includes numerical modeling using the finite-difference method and developing a calibrated building energy model of an existing residential building. Sensitivity analysis is conducted to evaluate the influence of thermal conductivity and heat capacity on cooling energy consumption. Correlation analysis is performed to assess the relationship between optimal thermal diffusivity and cooling degree days. The results highlight the importance of finding a balance between thermal insulation and thermal mass for energy-efficient buildings, considering the unique climate conditions in Saudi Arabia. Finally, this study considered the development of the Saudi Energy Conservation Code (SBC-602), which provides guidelines and regulations for energy-efficient building design in Saudi Arabia by recommending the selection criteria for the optimal thermal properties of building walls while considering the outdoor climate conditions. By aligning the findings of this study with the requirements and recommendations of the SBC-602, the study aims to contribute to the effective implementation of energy-efficient strategies in building design. [ABSTRACT FROM AUTHOR]

High-performance building envelope materials, components and systems have been developed to achieve reduction in energy demand and meanwhile maintaining a satisfactory indoor environmental quality. The performance of building envelopes is generally assessed through numerical and experimental methods. Experimental work conducted with outdoor testbeds provides live data under real weather conditions, and therefore become an effective approach to evaluating the performance façade technologies. This paper reviewed 82 outdoor testbeds employed in studies on performance of building envelopes. They are categorized according to scale and form. Representatives in each category are discussed in details, and the main features are compared and summarized systematically. The functions of testbeds are analyzed according to the dedicated experimental purposes. Different construction materials and structures are also compared. On this basis, recommendations are made for future design, construction and application of outdoor testbeds. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the possibility of using two different methods together to detect more accurately and to evaluate thermal defects in the envelope of agricultural buildings. The structure of heated agricultural buildings is significantly influenced by the characteristics of the indoor environment (aggressive gaseous and liquid substances, high humidity, higher heating temperatures, etc.). In this study, research has been conducted that synergistically combines two methods for the evaluation of thermal defects, where the structure is evaluated using infrared thermography and at the same time described as a numerical model for a more detailed identification of envelope defects and thermal bridges. The study confirmed that in agricultural building structures, thermal defects are most commonly found in the areas of window lintels, ceiling and bracing structures, window and door joints, and foundation and floor joints, while the proposed combination of the two methods for assessing thermal defects in structures demonstrated superior performance in terms of accuracy and detail of results obtained compared to the standard partial use of only one of these methods. [ABSTRACT FROM AUTHOR]

Concern for unsustainable buildings has obliged the global construction industry to embrace energy-efficient building envelope. In Mauritius, building insulation like the eco-block technology was initiated to reduce energy consumption from air-conditioning, ensure energy cost savings and improve thermal comfort. An investigation of the factors which motivate society's acceptance of the new building is important to enable its wider-scale implementation. Normally, the adoption decision-making process is a generic model to understand the different stages leading to the purchase decision of a specific innovation. However, the model is restricted in terms of obtaining an in-depth contextual understanding towards the selection process. The contribution of this research is, therefore, to develop a new adoption decision-making framework that aims to explore the contextual factors and examine Mauritians' purchase decision of the eco-block building, filling the literature gaps. A survey questionnaire was designed and distributed to Mauritians based on the researcher's judgment, where 257 responses were useful to undergo structural equation modelling. The findings revealed that dissatisfaction with the thermal comfort of existing buildings during hot season, importance to reduce energy, household size, internal product features, economic incentives and public education have significant influence on the building acceptance. Contrastingly, building age, awareness of building insulation alternatives, external product features and past experience have no effect on adoption decision. Accordingly, the predictor variables within the contextual model could satisfactorily explain 21.1% of the eco-block building purchase behaviour. The contextual framework can eventually assist building developers to use the research outcomes and formulate successful implementation strategies. [ABSTRACT FROM AUTHOR]

Addressing the challenges of scalable and cost-effective energy performance analysis in mid to high-rise office buildings, this paper introduces a novel approach utilizing an inverse-based artificial neural network (ANN). This ANN was trained on synthetically generated heating and cooling load parameters – derived from simulations conducted in EnergyPlus – to predict characterization parameters, including the building envelope, internal heat gains, and HVAC operational parameters. Diverging from traditional forward surrogate models, this inverse surrogate model fills a critical gap in current building energy modeling approaches that are hindered by data and resource limitations. Its effectiveness is verified with a testing dataset of 3000 buildings and is further demonstrated through a case study in Ottawa, Ontario. Proving to be an efficient, cost-effective tool for energy retrofit screening, the model is enhanced by a user-friendly web-based application (Ferreira and Gunay), marking a significant advancement in accessible building energy analysis. [ABSTRACT FROM AUTHOR]

Residential homes and apartments' cooling and heating needs account for 63% of total building energy consumption. Improvements in the properties of building envelopes are among the best ways to reduce their energy consumption. The project's general objective was to compare the performance of externally insulated and traditional envelopes of light wooden frame buildings at full scale. Two houses were constructed and equipped with relative humidity sensors and temperature probes to assess the physical properties of the building envelope. The first house was built according to the conventional method (insulation between the studs), and the second house was built according to the method with the insulation outside the wall (also known as the perfect wall). The results showed that external insulation effectively mitigates internal condensation risks by relocating dew points to the exterior surface, thereby enhancing structural durability and thermal stability. Thermographic imaging confirmed reduced thermal bridging and improved thermal performance in the externally insulated walls. Overall, this study supports, with a full-scale experiment, the adoption of external insulation as a viable strategy for enhancing energy efficiency, thermal comfort, and durability in residential buildings. [ABSTRACT FROM AUTHOR]

In response to increasing global temperatures and energy demands, optimizing buildings' energy efficiency, particularly in hot climates, is an urgent challenge. While current research often relies on conventional energy estimation methods, there has been a decrease in the efforts dedicated to leveraging AI-based methodologies as technology advances. This implies a dearth of multiparameter examinations in AI-driven extreme case studies. For this reason, this study aimed to enhance the energy performance of residential buildings in the hot climates of Dubai and Riyadh by integrating Building Information Modeling (BIM) and Machine Learning (ML). Detailed BIM models of a typical residential villa in these regions were created using Revit, incorporating conventional, modern, and green building envelopes (BEs). These models served as the basis for energy simulations conducted with Green Building Studio (GBS) and Insight, focusing on crucial building features such as floor area, external and internal walls, windows, flooring, roofing, building orientation, infiltration, daylighting, and more. To predict Energy Use Intensity (EUI), four ML algorithms, namely, Gradient Boosting Machine (GBM), Random Forest (RF), Support Vector Machine (SVM), and Lasso Regression (LR), were employed. GBM consistently outperformed the others, demonstrating superior prediction accuracy with an R2 of 0.989. This indicates that the model explains 99% of the variance in EUI, highlighting its effectiveness in capturing the relationships between building features and energy consumption. Feature importance analysis (FIA) revealed that roofs (29% in Dubai scenarios (DS) and 40% in Riyadh scenarios (RS)), external walls (19% in DS and 29% in RS), and windows (15% in DS and 9% in RS) have the most impact on energy consumption. Additionally, the study explored the potential for energy optimization, such as cavity green walls and green roofs in RS and double brick walls with VIP insulation and green roofs in DS. The findings of the paper should be interpreted in light of certain limitations but they underscore the effectiveness of combining BIM and ML for sustainable building design, offering actionable insights for enhancing energy efficiency in hot climates. [ABSTRACT FROM AUTHOR]

Stone curtain walls are widely used in contemporary architectures; however, their regular inspection is always labor-intensive, time-consuming, and hazardous due to the complex and enclosed spatial structure of these high-rise building enclosures. To address this issue, this study proposes an automated and novel inspection method, which is composed of the following three steps: First, we utilize 3D laser scanning technology to capture colored point cloud data of the stone curtain wall system; subsequently, by extracting and processing the integration of color and depth information, the stone panels and end sealants are precisely segmented; finally, various defects, such as cracks, unevenness, and irregularities, are automatically identified through artificial intelligence algorithms in a timely manner. To validate the proposed method, an on-site experiment was carried out to demonstrate the effectiveness in detecting multiple defects concurrently on stone curtain walls. The experimental results showed that our proposed method could provide a non-contact and automated inspection alternative for all the stone curtain walls with a high accuracy of anomaly detection, facilitating rational maintenance plans and strategies to ensure the safety and performance of these modern building enclosures. [ABSTRACT FROM AUTHOR]

The adaptive façades serve as the interface between the indoor and outdoor energy of the building. Adaptive façade optimization design can improve daylighting performance, the thermal environment, view performance, and solar energy utilization efficiency, thus reducing building energy consumption. However, traditional design frameworks often neglect the influence of building envelope performance characteristics on adaptive façade optimization design. This paper aims to reveal the potential functional relationship between building façade performance characteristics and adaptive façade design. It proposes an adaptive façade optimization design framework based on building envelope performance characteristics. The method was then applied to a typical office building in northern China. This framework utilizes a K-means clustering algorithm to analyze building envelope performance characteristics, establish a link to adaptive façade design, and use the optimization algorithm and machine learning to make multi-objective optimization predictions. Finally, Pearson's correlation analysis and visual decision tools were employed to explore the optimization potential of adaptive façades concerning indoor daylighting performance, view performance, and solar energy utilization. The results showed that the optimized adaptive façade design enhances useful daylight illuminance (UDI) by 0.52%, quality of view (QV) by 5.36%, and beneficial solar radiation energy (BSR) by 14.93% compared to traditional blinds. In addition, each office unit can generate 309.94 KWh of photovoltaic power per year using photovoltaic shading systems. The framework provides new perspectives and methods for adaptive façade optimization design, which helps to achieve multiple performance objectives for buildings. [ABSTRACT FROM AUTHOR]

The need to construct environmentally friendly buildings to meet current environmental and ecological standards is urgent. This study introduces a new multi-layer construction material with two outer layers of ordinary mortar and an inner layer of a pozzolane-limes composite to meet this need. The thermal efficiency of this material in building construction is investigated using TRNSYS18 simulations for two distinct climatic zones in Morocco, with a particular focus on its impact on heating dynamics. The primary objective is to evaluate the thermal performance of multi-layered pozzolanic materials, for which mortar samples are meticulously prepared as a reference in the two different climatic zones (Azilal and Errachidia). Using the asymmetric hot plate method under both stable and transient conditions, the authors conduct thermal characterization experiments. The results underscore the improvement in thermal performance made possible by the incorporation of pozzolan as an aggregate in the multi-layer material compared to ordinary mortar. Specifically, thermal conductivity improves significantly, from 0.735 W m−1 K−1 for ordinary mortar to 0.4 W m−1 K−1 for multi-layered pozzolanic materials, representing a 46% mass gain. Additionally, effusivity decreases from 730 to 604 J m−2 K−1 s−1/2, while diffusivity decreases from 3.78 to 2.23 × 10−7 m2 s−1, further attesting to the material's thermal efficacy. TRNSYS18 simulations corroborate the viability of using multi-layered materials as building envelopes, revealing potential annual heating gains of 25% in Azilal and 5% in Errachidia. These findings underscore the promising prospects of integrating these materials into sustainable construction practices. [ABSTRACT FROM AUTHOR]

The demand for sustainable building materials and systems with the emphasis on energy efficiency is on the rise. Insulating Concrete Forms (ICFs) are an example of such structural systems. Screen Grid Insulated Concrete Forms (SGICFs) are an innovative system that combines structural strength and thermal performance. ICF walls are commonly used in Western countries to provide high-level insulation and internal weather control. Accordingly, the current research conducts a comparative thermal analysis for a market-supplied ICF wall, a SGICF proposed design, and three typical brick walls used regionally in the Middle East. The heat transfer through the five walls is simulated by COMSOL Multiphysics and validated experimentally by utilizing a guarded hot box facility under the regulations of the ASTM C1363 standard. The market-supplied ICF walls showed better thermal insulation properties than the proposed SGICF walls, because of their higher thermal mass of concrete than in the SGICF walls. However, both walls had a remarkably higher insulation performance than the other three typical brick walls available in the market. The results reveal that the market-supplied ICF walls are overdesigned for use in the Middle East region, and SGICFs, with their comparative thermal transmittance, are a very good competitor in the Middle East market. [ABSTRACT FROM AUTHOR]

This perspective article describes the past, present, and future directions on TiO2 photocatalysis, 3D concrete printing, and recycling for developing innovative building envelope components from façade skins. Using a methodology consisting of three phases, first the historical evolution of TiO2 photocatalysis, 3D concrete printing, and recycling policies was investigated. Second, the rationale and positioning with regard to the state of the art were developed. Third, the cementitious mix design assessment for 3D printing of the building envelope components, evaluation of the photocatalytic activity, evaluation of the self-cleaning and air-purifying properties, and environmental and health assessment of the building envelope components were identified and discussed as major issues in developing innovative building envelope components that have the potential to mitigate urban air pollution, reduce building maintenance activities, and reduce building embedded carbon while, for example, recycling significant amounts of construction and demolition waste. [ABSTRACT FROM AUTHOR]

This article focuses on the thermal bridging issues associated with interface of parkade concrete suspended slab to base of wall. The study aims to determine the optimal length and thickness of insulation at the top and underside of the suspended slab to minimize heat loss. The thermal performance of wall to parkade suspended slab is investigated, for both wood frame and steel stud constructions. Various insulation configurations are proposed and evaluated, including different lengths and thicknesses of extruded polystyrene foam (XPS) and Fiberglass spray insulations. The thermal performance calculations are conducted using steady-state heat transfer analysis. A finiteelement based software is utilized for the simulations. The study provides a detailed methodology for analyzing the thermal performance of building envelope details, considering different insulation configurations. The results of the simulations are presented as Thermal Resistance Values (R-Values) and Linear Thermal Resistance Values (PSI-Values), allowing for a comparison of the thermal efficiency of different insulation configurations. The results show that utilizing the optimal insulation configuration can lead to up to 80 % enhancement in the thermal efficiency of the assembly. The findings serve as a guideline and aim to assist building designers in improving the thermal performance of concrete suspended slabs. [ABSTRACT FROM AUTHOR]

This study investigates the thermal performance of polymer-modified concrete composites, focusing on their potential to enhance energy efficiency in building envelopes. Four types of recycled polymers—low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (POLYP), and polyester—were integrated into concrete mixes at varying percentages (10%, 20%, and 30%). Key thermal metrics, including thermal transmittance (U-value), decrement factor (f), decrement delay (ϕ), admittance (Y), optimum thickness, and heat capacity per unit area, were measured using the admittance approach and a MATLAB program conforming to CIBSE standards. Results indicate that higher polymer content generally improves thermal damping and reduces cyclic transmittance. Notably, LDPE 30% exhibited the best performance, achieving a decrement factor of 0.179 and a time lag of 11.76 hours. HDPE 30% demonstrated a decrement factor of 0.206 and a time lag of 10.85 hours. Polyester 30% showed a decrement factor of 0.310 and a time lag of 8.50 hours. Sensitivity analysis revealed that optimal wall thicknesses for polymer-modified concretes are lower than those required for conventional concrete, with LDPE 30% requiring an optimal wall thickness of 0.128 meters compared to 0.269 meters for conventional concrete. This research underscores the dual benefits of waste management and energy performance improvement, advocating for the practical application of polymer-modified concrete in sustainable construction. The study ranks the polymers' efficiency as LDPE, HDPE, POLYP, and Polyester. These findings support the use of recycled polymers in concrete, promoting sustainability through effective waste management and improved thermal efficiency in building envelopes. [ABSTRACT FROM AUTHOR]

Cogeneration is an important means for heat supply enterprises to obtain heat, and accurate load prediction is particularly crucial. The heat load of a centralized heat supply system is influenced by various factors such as outdoor meteorological parameters, the building envelope structure, and regulation control, which exhibit a strong coupling and nonlinearity. It is essential to identify the key variables affecting the heat load at different heating stages through data mining techniques and to use deep learning algorithms to precisely regulate the heating system based on load predictions. In this study, a heat station in a northern Chinese city is taken as the subject of research. We apply the Fuzzy Clustering based on Fourier distance (FCBD-FCM) algorithm to transform the factors influencing the long and short-term load prediction of heat supply from the time domain to the frequency domain. This transformation is used to analyze the degree of their impact on load changes and to extract factors with significant influence as the multifeatured input variables for the prediction model. Five neural network models for load prediction are established, namely, Backpropagation (BP), convolutional neural network (CNN), Long Short-Term Memory (LSTM), CNN-LSTM, and CNN-BiLSTM. These models are compared and analyzed for their performance in long-term, short-term, and ultrashort-term heating load prediction. The findings indicate that the load prediction accuracy is high when multifeatured input variables are based on fuzzy clustering. Furthermore, the CNN-BiLSTM model notably enhances the prediction accuracy and generalization ability compared to other models, with the Mean Absolute Percentage Error (MAPE) averaging within 3%. [ABSTRACT FROM AUTHOR]

This paper provides an analysis of challenges and available solutions for exterior insulated panels suitable for deep energy retrofits of existing building envelopes. The analysis covers a review of available technologies that provide flexible retrofit insulated panels suitable for multiple climates and building typologies. Moreover, the paper proposes a new design for insulated retrofit panels that account for the majority of identified technical risks including cost, architectural diversity, climate variations, structural concerns, moisture resilience, air sealing, and water sealing. Additionally, the proposed design can be easily installed with minimal disruption to the occupants. A series of parametric and optimization analyses is carried out to identify the optimal design specifications for insulated panels suitable for deep retrofits of existing US housing stocks. The analysis results show that the optimal design criteria for the insulated panels can reduce heating and cooling energy consumption by up to 80% and HVAC capacities by 70%. Moreover, the results indicate that these insulated panels are highly cost effective for retrofitting US housing units located in cold climates. [ABSTRACT FROM AUTHOR]

This paper investigates the theoretical and experimental cooling performance of textile materials utilizing radiative cooling technology. By applying Kirchhoff's law, the emissivity of surfaces is determined, revealing that materials with high transmission values can achieve comparable cooling performance to those with high reflection values. Notably, materials exhibiting moderate reflectance and transmittance in the solar range tend to absorb minimal solar radiation, thus offering high theoretical cooling performance. However, practical applications like building envelopes or clothing present challenges due to the impact of background radiation on overall cooling capacity. Despite their intrinsic cooling properties, a significant portion of solar radiation is transmitted, complicating matters as the background can significantly affect overall cooling performance. This study provides a solution that accounts for the influence of background materials. Based on spectral data, various background materials and their impact on different semi-transparent comparison materials can be considered, and cooling performance can be simulated. This enables the simulation of cooling performance for various application scenarios and facilitates comparisons between transparent, semi-transparent, and opaque textile materials. [ABSTRACT FROM AUTHOR]

Featured Application: This article applies to building maintenance and the life-cycle assessment of repair operations. The possibility of diagnosing and repairing specific sets of defects (those with more severe consequences and impact on the degradation of building components) with the same means is considered. It is important to optimise the planning and kick-off of building inspections by using, from the start, a predetermined set of equipment and to optimise the maintenance and rehabilitation of the building envelope in terms of funds invested and resources. An existing methodology is used to create inter-defect correlation matrices, taking into account an expert knowledge-based building inspection system. The main results include a set of essential diagnosis methods—crack measuring and monitoring; temperature and moisture measurement; infrared thermography; and water absorption tests—and the identification of the most transversal repair techniques—cleaning; protection coating; replacement/reapplication of claddings/glazing; re-application of finishing coats or more adequate claddings—which were also analysed in terms of resource consumption, as a preliminary approach to their life-cycle assessment. The main conclusions indicate that there is still a long path to cover in the field of life-cycle assessment of repair techniques, which can be extended to the application of diagnosis methods. [ABSTRACT FROM AUTHOR]

Moisture ingress in photovoltaic (PV) modules is a critical factor for performance degradation, therefore, a low water vapor transmission rate (WVTR) is highly desirable for polymers used to embed the solar cells, including backsheets, frontsheets, and encapsulants. With the advent of glass‐free modules for integration in building envelopes and vehicles, there is growing interest in polymer composite structures with embedded glass fibers to enhance rigidity. Furthermore, due to environmental concerns, there is increased interest in fluorine‐free polymers for PV applications. In this work, 21 samples with different base polymers, coatings, and/or surface treatments are investigated and their WVTRs are measured. The results show no good alternatives to existing fluoride‐based polymers/coatings for reducing WVTRs of backsheets and frontsheets among the investigated samples. In addition, glass fibers embedded within polymers to provide increased stability to backsheets or in composites for lightweight PV are shown to significantly increase WVTRs, especially, when fibers are not properly embedded, providing additional diffusion pathways for moisture ingress. [ABSTRACT FROM AUTHOR]