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The Urban Heat Island (UHI), a consequence of urban development, leads to elevated temperatures within cities compared to their rural counterparts. This phenomenon results from factors such as urban designs, anthropogenic heat emissions, and materials that absorb and retain solar radiation in the built environment. Materials commonly used in cities, like concrete, asphalt, and stone, capture solar energy and subsequently emit it as heat into the surroundings. Consequently, this phenomenon amplifies summertime cooling energy demands in buildings. To mitigate the UHI impacts, various mitigation strategies have emerged that include but are not limited to using higher solar reflectivity materials, known as “cool materials”, and increasing vegetation and greenery in urban areas. Cool materials have high reflectivity and emissivity, effectively reflecting solar radiation while emitting absorbed heat through radiative cooling. Increasing the solar reflectivity of building envelope materials is a promising sustainable solution to lessen the UHI effects. This state-of-the-art review summarizes the UHI causes and effects, states the mitigation strategies, describes the cool building envelope materials, explains the solar reflectivity index measurements, indicates the building and micro-climate simulations, highlights the performance evaluation of using cool building envelope materials, points out the research gaps, and proposes future research opportunities.

This study investigates, both experimentally and theoretically, the impact of incorporating window shutters on the thermal resistance of double-glazed window units, employing computational fluid dynamics (CFD) modelling. The integration of shutters, whether installed internally or externally, introduces an additional air layer that significantly influences heat transfer between indoor and outdoor environments. This effect on the thermal performance of the transparent structure was analysed through experimental measurements under real operating conditions and numerical simulations involving fluid dynamics and energy equations for the air gaps, alongside heat conduction equations for the solid components. Fourth-kind boundary conditions, considering both radiative and conductive components of the total heat flux emanating from the building’s interior, were applied at the solid–gas interfaces. The simulation results, comparing heat transfer through double-glazed windows with and without shutters, demonstrate a substantial increase in thermal resistance, ranging from 2 to 2.5 times, upon shutter implementation. These findings underscore the effectiveness of employing shutters as a strategy to enhance the energy efficiency of windows and, consequently, the overall energy performance of buildings. This research contributes to the advancement of sustainable materials for engineering applications by providing insights into the optimisation of thermal performance in building envelopes.

Purpose of Review The main goal of this study was to review the latest developments in the use of wood-based building materials and systems over the last 5 years. The methodology was carried out by using the systematic review procedure. This study considered only peer-reviewed articles written in English published over the last 5 years (2018 to 2022) on materials used in structural systems and building envelopes. Recent Findings The energy demand for cooling and heating represents from 40 to 60% of a building’s energy consumption depending on the energy mix. Every increase in energy efficiency increases the pressure on the energy embedded in the materials. In this context, bio-based and especially wood-based materials are gaining popularity. Their use is significant in structural and envelope systems, making them a powerful tool for working on both efficiency and embedded energy. Furthermore, the building construction industry is among the most significant in the economy of industrialized countries. Summary Forests are a carbon asset for our societies. Since buildings have been identified as a global warming mitigation tool, an increase in the use of wood and bio-based products should be considered. To support a better scientific understanding of building carbon sequestration under climate changes, a thorough understanding of structural and envelope systems is needed. Various materials are used in these complex systems, and a variety of assembly options are available. In structural systems, research has tended to be incremental over the last 5 years, with a focus on prefabrication and hybrid structures. As new designs and materials are introduced in the future, building physics principles will become increasingly important to ensure the quality of building envelopes. This review presents the latest research related to wood structural and envelope systems to support their use in the construction industry.

Building envelopes represent the interface between the outdoor environment and the indoor occupied spaces. They are often considered as barriers and shields, limiting solutions that adapt to environmental changes. Nature provides a large database of adaptation strategies that can be implemented in design in general, and in the design of building envelopes in particular. Biomimetics, where solutions are obtained by emulating strategies from nature, is a rapidly growing design discipline in engineering, and an emerging field in architecture. This paper presents a biomimetic approach to facilitate the generation of design concepts, and enhance the development of building envelopes that are better suited to their environments. Morphology plays a significant role in the way systems adapt to environmental conditions, and provides a multi-functional interface to regulate heat, air, water, and light. In this work, we emphasize the functional role of morphology for environmental adaptation, where distinct morphologies, corresponding processes, their underlying mechanisms, and potential applications to buildings are distinguished. Emphasizing this morphological contribution to environmental adaptation would enable designers to apply a proper morphology for a desired environmental process, hence promoting the development of adaptive solutions for building envelopes.

PurposeDecarbonizing cities is one of today’s biggest challenges. In this regard, particular attention has been paid on improving the environmental performance of buildings. In this framework, this work consists in assessing the environmental impact of an innovative building envelope component derived from urban agriculture (UA) wastes. In fact, rooftop UA seems to be a possible solution to the rising food demand due to increasing urban demographic growth. Consequently, rooftop UA wastes need to be treated in sustainable ways.MethodsThis study aims to determine the carbon footprint and embodied energy of a new infill wall material, derived from UA wastes produced by a building rooftop greenhouse tomato crop, and evaluate the potential biogenic carbon that such by-product could fix temporally until its end of life. After an initial description of the manufacturing process of the new material, its carbon footprint and embodied energy have been calculated by means of the life cycle assessment (LCA) methodology according to the ISO 14044 and the ISO 14067 guidelines adapted to the analyzed context. In particular, the inventory analysis is based on data collected from the production of samples of the new material at the laboratory scale.Results and discussionThe results of the LCA indicate that, when the biogenic carbon fixed in the UA wastes is considered, a negative carbon footprint of − 0.2 kg CO2 eq. per kg of material can be obtained. Hence, it can be assumed that from a life cycle perspective the material is able to fix carbon emissions instead of emitting them. Specifically, for the considered scenario, approximately 0.42 kg CO2 eq./m2 per year could be sequestered. However, the crop area required to produce enough waste to manufacture a unit of material is quite high. Therefore, future studies should focus on individuate solutions to reduce the density of the new component, and also different urban crops with higher waste production rates.ConclusionsThe outcomes of the study put in evidence the potential of the new proposed infill wall component in fixing carbon emissions from UA, allowing to also compensate those relating to the production and transportation stages of the component life cycle. Moreover, producing by-products with UA wastes, hence temporally storing the carbon fixed by crops, may contribute to reduce the carbon cycles speed conversely to traditional waste management solutions, other than lower new raw materials depletion.

Population growth, urbanization, and climate change have significantly contributed to environmental degradation, posing severe consequences for humans and other species. By integrating ecological objectives with human-centric goals, a path towards a sustainable, multi-species future is possible. Current sustainable design principles have shown positive environmental impacts by addressing human-centric objectives such as enhancing green infrastructure, energy efficiency, thermal comfort, and more. However, the incorporation of multi-species design criteria remains unresolved. This paper proposes a conceptual framework in which human-centric and ecological design objectives are defined and associated through the selection of key performance indicators (KPIs) represented by numerical thresholds. But, while the objective-KPI relationship is an established path in architectural design, the same does not apply for preserving and promoting biodiversity. The proposed conceptual framework identifies, defines, and associates the relevant objective-KPI relationships for all stakeholders and becomes the basis for evaluating the project computationally. Such an approach is currently lacking.

The context for this article is sustainable and ecological green city and building design; the intent is to advance architecture and ecology integration and multi-species design in architecture through the development of a conceptual framework for and computational approach to the early-stage design of ecological building envelopes, which are enclosures of buildings that make provisions for humans, plants, and animals. This entails two research questions: (1) how to integrate architectural and ecological domain knowledge into a conceptual and methodological framework and (2) how to develop a computational workflow and components for the early-stage design of ecological building envelopes. A mixed-method approach was used to develop an ontology-aided generative computational design process that combines computational ontologies, a voxel model, and rule-based processes that generate design variety. The process was developed to support two dominant design cases in architectural practice: masterplan design and building design. This article outlines the underlying key concepts, the computational workflow, and the developed key computational components and summarily indicates validation approaches during the development process. Finally, thoughts on the technical implementation of the computational workflow and components are indicated and further research questions are outlined.

Air-permeable building envelopes (APBEs) utilize the infiltrated or exfiltrated airflow within porous materials to directly change their temperature distribution to reduce heat loss/gain. APBEs effectively integrate building ventilation and heat recovery to achieve excellent thermal insulation while improving indoor air quality. This paper presents a comprehensive review of the fundamentals and classifications, historical evolution over time, opportunities and benefits, and future views on APBEs. It can be treated as a responsive building envelope that enables building envelopes to dynamically change the U-values by varying the infiltrated or exfiltrated airflow rate within a porous material. Previous studies have indicated that the U-value of 0.1 W/(m2·K) can be realized by employing APBEs. Moreover, some research demonstrates that APBEs could act as high-performance air filters that reduce over 90% of particulate matter within fresh, ventilated air. Some factors, such as airflow rate, thickness, and thermal conductivity of porous materials, have a significant influence on the effectiveness of APBEs. For practical applications, integrating the APBE with passive building ventilation can help reduce the initial cost and facilitate decarbonization in buildings. Moreover, advanced control strategies could collaboratively optimize the operation of ABPEs and build energy systems to maximize their energy-saving potential.

This experimental study explores the integration of Phase Change Materials (PCMs) within building envelopes. The research specifically centers on the utilization of two microencapsulated paraffin-based PCMs with melting points of 37 °C and 43 °C. The study assesses their performance within cement and gypsum-based PCM composites, concentrating on service areas often overlooked in thermal analysis, including underground garages, staircases, and utility rooms. The experimental setup included constructing three chambers inside an underground garage during the hot months of June and July in Saudi Arabia. Two chambers were assigned to integrate the PCM, while the third chamber served as a control without PCM. The experiment unfolds in two phases. In the initial phase, the objective was to determine which PCM is more effective in reducing the heat load inside the chambers. This led to the adoption of the 43 °C PCM for the subsequent stage. The adoption of the 43 °C PCM resulted in a fourfold decrease in heat compared to the 37 °C PCM. The second phase investigates the integration of the selected PCM with cement and gypsum composites. The percentage of PCM incorporated into the concrete and gypsum composites was determined experimentally. For cement-based composites, the identified percentage that maintains material integrity is 20%, and for gypsum-based composites, it is 22%. The findings demonstrate a significant reduction in cooling load with PCM incorporation, with cement-based composites exhibiting superior thermal performance compared to gypsum-based alternatives and reducing the heat load by approximately 63%. Additionally, it was observed that concrete reduced the highest temperature during the day by 5.2 °C, which equates to about a 10% reduction, further enhancing comfort. Conducted over the course of two summer seasons, this study contributes valuable insights toward improving the quality of life for building occupants, considering various factors such as their living environment.

One trend in building design is building envelopes with perforated patterns, which create a sculptural envelope using parametric and generative design tools to adapt to environmental conditions and user preferences. However, there are gaps in understanding the potential benefits of perforated building envelopes (PBEs) and their key design parameters used in contemporary projects. Therefore, this study aims to examine the classification of PBE design parameters and their commonly used parametric design tools that provide appropriate indoor environmental quality (IEQ) for buildings. The study is based on (1) a review of relevant studies, and (2) an analysis of case studies of contemporary projects. The results reveal relationships between key design variables of contemporary PBEs based on a conceptual framework developed in terms of (a) general building properties, (b) detailed envelope properties, and (c) environmental performance indicators. This study contributes to the field of architecture by providing a design strategy for creating PBEs based on a parametric approach and highlights the importance of considering IEQ in the early digital modelling process. By applying the five-stage strategy: creativity, configuration, generation, performance, and evaluation, it was found that PBEs can be a powerful tool to enhance energy efficiency by about 26.91% compared to glazed envelopes in Egypt, which may lead to improved IEQ. Future research could apply the proposed strategy to explore the impact of PBEs on various IEQ indicators. Highlights Improving Indoor environmental quality by perforated building envelopes (PBEs) is investigated. Developing a conceptual framework for classifying PBE design parameters. Uncovering the interrelationships between key design variables in contemporary PBEs. The study presents a five-stage strategy based on a parametric approach. Evaluation using parametric tools can significantly enhance the energy efficiency of PBEs by 26.91%.