The European building stock demands urgent renovation due to the age of the buildings, their expected lifetime, and their excessive energy consumption, which accounts for more than a third of the EU’s total emissions. However, the complexities involved, such as time, costs, and structural modifications, often discourage clients, tenants, and occupants from undergoing a building renovation process. Textile membranes, despite their long history in various architectural applications, have only been employed in façades in the last decades. Their intrinsic properties, such as lightness and flexibility, together with rapid assembly and low maintenance make these materials particularly suitable for façade retrofitting. Therefore, they are worth exploring as a way to promote the development of lightweight and easy-to-assemble façade products that could help overcome the current limitations of building retrofitting efforts. This paper aims to establish relationships between textile membranes and potential building retrofit applications. To this end, this study builds on the categorization of traditional façade retrofit strategies and proposes a new classification for textile façade retrofit products. The methodology includes a comprehensive literature review of textile properties and characteristics, along with a thorough assessment through case studies, of membrane use in façade applications. A sequential investigation leads to the main outcome of identifying three clear pathways for the development of new textile-based façade products for building retrofit.

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Additive Manufacturing with Varying Material Properties enables controlled spatial variation of material properties in 3D-printed components, facilitating custom-tailored characteristics, added functionalities and reduced assembly processes. To promote this approach in building façade applications, this paper presents a novel framework for Additive Manufacturing with varying material properties using a thermosetting reactive polymer, specifically polyurethane. By dynamically changing the polyurethane’s chemical composition, the material properties can be precisely controlled. The framework’s individual aspects, including the material, hardware setup and computational system, are described in detail. Additionally, the research explores the implementation of material transitions with this framework, highlighting three different modes (horizontal, vertical and multi plane) and their impact on print time and material consumption. The paper concludes by discussing the potential of this approach for building façade applications, addressing current challenges and outlining future research directions.@en

Residential buildings in the Kingdom of Saudi Arabia (KSA) contribute to nearly half of the overall electricity consumption in the building stock, highlighting their significant role in energy consumption. While an upgraded energy code has been established and enforced for new buildings, existing buildings continue to operate at the same level of energy consumption. Therefore, there is a need for further energy upgrades in existing buildings. This study evaluates the energy savings potential of various energy retrofitting measures for a case study in Jeddah, KSA. Data from previous studies and current practices were collected and analyzed. Different energy upgrade measures, such as windows replacement, wall insulation upgrade, roof insulation upgrade, and air conditioning unit replacement, were selected and evaluated using a digital simulation tool called Design-Builder. The simulation results were compared to understand the potential percentage of energy savings. The average annual energy consumption (AAEC) was used as the primary performance indicator to compare the energy savings among the scenarios. The results demonstrate significant reductions in energy consumption for the proposed scenarios. Furthermore, the study examined the significant impact of uncertainties, specifically, the infiltration rate and AC setback temperature, on AAEC. In conclusion, the proposed scenarios have the potential to achieve substantial energy savings, ranging from 25% to 66%, depending on the number of energy retrofitting interventions employed. The findings of this study can serve as a useful reference for similar energy retrofitting projects.@en

People in cities are often exposed to complex mixtures of sounds, some originating from nature along with some created by human activities like traffic noise, sounds of industrial machinery, or music. This research aimed to study how the acoustic environment of a university campus is perceived by people. The procedures for soundscape data collection and analysis were based on the ISO 12913 series. 30 volunteers divided into four groups participated in a “soundwalk” at the campus of the architecture school in Detmold, Germany, filling out questionnaires while sound measurements and recordings were being taken. After the soundwalk, the data from the questionnaires, sound measurements, recordings, pictures and videos were analyzed. The findings suggest that people’s perception of sound is susceptible to the context, as participants seemed to shift their preference according to the ongoing activities that drew attention, such as a construction site, sounds from children playing, music and groups of people. The results provide new evidence and insights about the acoustic environment and the soundscape of the university campus and can inform stakeholders to improve environmental quality.@en

This study aims to capture individual occupant preferences on window visual effects (daylight, glare, outside view, and privacy) concerning façade configuration and operation in a laboratory facility.@en

The application of façade products integrating solar cooling technologies tends to be one of the promising options to be considered for challenges related to the increase in global demand for cooling in the built environment. Accordingly, the technological innovation of such products represent an essential task to be taken into account for meeting the future cooling demand in buildings. However, selecting the right technology and tackling technical and product-related aspects in the context of solar cooling can be challenging, since each technology is different from one another in terms of their working principles. Furthermore, developing such building products can be a complex endeavour, due to the involvement of various components. This paper aims to propose a conceptual approach for designing and developing façade products integrating solar cooling technologies. Proposing this approach required establishing a matrix of key attributes and criteria affecting technological selection through referring to identified key perceived enabling factors by expert interviews in an earlier stage of the study. The outcomes of this study outlined various attributes, such as product performance and efficiency as well as compactness and space usability, that can be used in product development of solar thermally and electrically driven systems, in order to ensure to support the widespread application.@en

Under urgent sustainability targets, the building industry craves for renewable and recyclable biomaterials as cellulose is a fiber; Lignin is a plant-derived low-cost polymer with remarkable properties, yet its valorization is in its infancy. Recent studies have shown potentials to combine cellulose and lignin into a renewable bio-based material for the built environment, with the use of additive manufacturing to allow geometric customization and local control of material. However, previous studies also highlighted crucial issues to be solved. One main challenge is the lack of knowledge on combinations of lignin and cellulose with different binders to achieve a paste suitable for 3D printing, leading to a material applicable in the built environment. To contribute overcoming the challenge, this research aimed to explore various combinations of cellulose, lignin, and binders and to study the extrudability of the resulting paste using a clay extruder installed on a robotic arm. Several combinations were explored, evaluated, and compared. The four recipes with the highest scores were used to produce samples for tensile and three-point bending tests, water absorption and retention tests, and microscope analysis. The overall outcome has shown similarities between the mechanical properties of the mixture developed using methylcellulose as the binding agent and rigid polymer foams, such as the ones commonly used as insulation panels. Moreover, the material mix with the highest score in the preliminary assessment was further applied to fabricate samples with varied geometries to assess its potential and limitations combined with the fabrication process. Finally, two demonstrators were produced to explore the printing process for different geometric configurations: conceptual window frame and structural node were designed, and 3D printed as proof of concept.@en

Several studies performing building simulations showed that the automated control of façades can provide higher levels of indoor environmental quality and lower energy demand in buildings, in comparison to manually controlled scenarios. However, in several case studies with human volunteers, automated controls were found to be disruptive or unsatisfactory for occupants. For instance, automated façades became a source of dissatisfaction for occupants when they did not fulfil individual environmental requirements, did not provide personal control options, or did not correctly integrate occupant preferences with façade operation in energy-efficient controls. This article reviews current evidence from empirical studies with human volunteers to identify the key factors that affect occupant response to automated façades. Only twenty-six studies were found to empirically investigate occupant response to automated façades from 1998 onwards. Among the reviewed studies, five groups of factors were found to influence occupant interaction with automated façades and namely: (1) personal factors, (2) environmental conditions, (3) type and mode of operation, (4) type of façade technology, and (5) contextual factors.. Overall, occupant response to automated façades is often poorly considered in research studies reviewed because of the following three reasons: (i) the lack of established methods or procedures for assessing occupant response to automated façade controls, (ii) poor understanding of occupant multi-domain comfort preferences in terms of façade operation, (iii) fragmented research landscape, on one hand results are mainly related to similar contextual or climatic conditions, which undermines their applicability to other climates, while on the other hand the lack of replication within the same conditions, which also undermines replicability within the same condition. Lastly, this paper suggests future research directions to achieve a holistic and more comprehensive understanding of occupant response to automated façades, aiming to achieve more user-centric automated façade solutions and advanced control algorithms. In particular, research on the impact of personal factors on occupant satisfaction with automated controls is deemed paramount.@en

The global attention to solar cooling systems has increased during the last years as a result of the expected growth in the world cooling demand. Such systems encompass the use of renewable energy as the main driver for mitigating indoor temperatures. Currently, some of these technologies are mature enough for their commercial application in buildings. Building facades present high potential for the integration of such technologies. This is because of their direct effect on the indoor comfort of buildings, and also their ability to provide external surfaces exposed to the sun radiation. However, there are different challenges affecting the widespread application of solar cooling integrated façades. This paper aims to identify and categorize these challenges through conducting a comprehensive literature review. A literature review was conducted on scientific papers published in conference proceeding and scientific journals, through considering two databases, namely Scopus and Web of Science. Then the study suggested three main potential dimensions that should be tackled and integrated when supporting the widespread application of the façade integration a particular solar cooling technology. The dimensions include technical, financial, as well as process and stakeholder related aspects. Such proposed dimensions represent an initial step for identifying important aspects to be considered for supporting the product widespread application in the built environment.@en

Multi-Material Additive Manufacturing (MMAM) is an emerging manufacturing approach that is gaining interest in architecture and construction as an expansion of Additive Manufacturing. Hereby, different materials or material properties are combined in a single additive process in order to create objects that are composed of multiple materials. Ultimately, this approach introduces a new way of manufacturing and building, where assembly is no longer a necessity in order to combine multiple materials. Moreover, different potentials can be derived from the use of MMAM. Leading towards components with heterogeneous material composition and a high degree of adaption towards structural, environmental, and design criteria. This work provides an overview of the current state of MMAM in architecture and construction. Different processes and materials which have been reported are discussed and potentials, which emerge through the use of MMAM are described using specific use-cases.@en

The main bottleneck during the manufacture of complex geometry thin-walled GFRC structures is the time taken to make the timber or CNC machined moulds for each panel. Complex geometries are comprised of many unique panel forms and the extensive time and high costs of their manufacture often prevents their architectural intent from being fully realised. A novel mould-making process is proposed that uses a state-of-the-art flexible table with computer-controlled actuators to create free-formed geometry, fast-curing, dual-density, polyurethane moulds. This mould-making process was successfully tested by using sprayed GFRC to manufacture 9 different double curved intermediate moulds for a 10 m high GFRC self-supporting, thin-walled hyperbolic shell, with 12 mm thick panels at the base of the structure. The completed structure showcased the effectiveness of the novel mould-making process by reducing the production time from an estimated 100 days to 10 days. The primary outcome was the development and application of a new manufacturing method capable of casting complex geometry thin-walled GFRC panels with good surface quality that was suited to more rapid, cost-effective and automated large-scale production.

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Façades cover a significant amount of surfaces in cities and are in constant interaction with the acoustic environment. Noise pollution is one of the most concerning burdens for public health and wellbeing; however, façade acoustic performance is generally not considered in outdoor spaces, in contrast to indoor spaces. This study presents a systematic literature review examining 40 peer-reviewed papers regarding the effects of façades on the urban acoustic environment and the soundscape. Façades affect sound pressure levels and reverberation time in urban spaces and can affect people’s perception of the acoustic environment. The effects are classified into three groups: Effects of façades on the urban acoustic environment, including sound-reflecting, sound-absorbing and sound-producing effects; Effects of façades on the urban soundscape, including auditory and non-auditory effects; Effects of the context on the acoustic environment around façades, including boundary effects and atmospheric effects. @en

Adaptive façades are multifunctional systems that are able to change their functions, features, or behaviour over time in response to changing boundary conditions or performance requirements. As one of the significant developments in the façade industry over the last decade, the adaptive façade offers an intelligent solution that can decrease energy consumption and potentially increase users’ comfort in a building. From an engineering perspective, these advanced technologies aim to improve the overall performance of the building while generating a better indoor environment for the users, but unfortunately, investigations show that this goal is not always achieved. This is why, to bridge this performance gap, we embark on a change of perspective in façade design, from a technology-centred to a human-centred one. This research emphasizes that, with their changeability aspects, adaptive façade technologies offer unique potential, although the design of such façades requires a deeper understanding of users. With this as its focus, this paper aims to identify the factors affecting the user experience in a working environment, considering the interactions of the user with building services and façade systems from a holistic point of view, in which façade-user relationships are to be distinguished, towards the larger aim of developing a human-centred approach for adaptive façade design.

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Earth is one of the oldest and till now intensively used natural building material. Around 30% of the world population still lives or works in buildings constructed out of earth. Most of them dwell in simple huts of rural communities or traditionally hand-crafted buildings. However, a growing number of people looking for healthy, environmentally friendly buildings in so called developed societies experience benefits of earthen construction materials. Due to the hygrothermal potential of clay, these benefits of earthen constructions include evaporative cooling during cooling periods and stable relative humidity levels indoors during the heating season. In addition, earthen building materials may contribute to the urgently needed circular economy, as earthen constructions like earth blocks or earth dry boards are reusable and earth plasters and mortars are replasticisable through the addition of water, as long as no chemical binder is added. Research gaps regarding physical properties, missing standardisation concerning building law and modern construction methods, and a limited number of manufacturers are hindering a wide application of earthen construction worldwide. Meanwhile, new digital production techniques evolve, which may elicit the potential of earth as future building material. Therefore, this Ten Questions article presents the state-of-the art and research gaps related to earth as building material in light of the potential of new digital production techniques like robotic fabrication or additive manufacturing. Such discussion includes new opportunities to combine the natural performance of the material with future-oriented construction systems and a new growing circular economy.

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Additive production techniques such as 3D printing and robotics enable new production methods and possible uses for earth, as one of the most ancient building materials in the building industry. This study examines the potential of different building elements and components and their possible combinations made of or containing earthen building products. In addition to the 3D printing of lightweight, highly insulating external and heavy internal wall elements and load-bearing rammed earth walls for use as inner and outside walls are compared. Furthermore, the activation of the walls with water-based heating and cooling elements is taken into consideration. In particular, the sensitivity of earth to humidity and water has a positive effect on all life cycle phases from production through operation as a low-tech building to the end of use, i.e. the reuse as well as the possible return to natural cycles. The focus of the study is to assess the building material earth in light of modern production methodologies, the impact on indoor comfort and indoor air quality as well its life cycle assessment.@en

The study examines the existing technical basis in building practice for the application of cyber-physical systems on the façade. The associated intelligent cooperation of automated adaptive façade functions, inspired by intelligent technical systems in industry 4.0, offers a potential for the overall building performance. By the type and scope of automations already introduced today, façade functions are identified that offer special potential for consideration in a cyber-physically implemented façade. The investigation represents a multiple case study analysis in which office façades in Germany are examined. Data is collected from literature, expert interviews and field investigations. The evaluation is carried out in a single case analysis and a following cross-case analysis, in which patterns and dependencies in the joint implementation of automated and adaptive façade functions are identified. The study found that especially sun-related functions are implemented adaptively, often in combination with ventilation and the heating and cooling support function.

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This research examines the technical feasibility of façades as cyber-physical systems, which can revolutionize former hierarchical and closed automation concepts of mechatronics through their cooperation of decentralized entities. While such systems are already employed in many application fields to increase the flexibility and performance of automated processes, a transfer to the operation of automated adaptive façades has not yet been investigated. In this study, a prototype is developed to systematically test the application of individual cyber-physical system criteria to façades. The prototype is organized in modules, each of which represents one instance of the selected façade functions of solar shading, natural and mechanical ventilation, and heating and cooling. The emphasis lies on development of a communication system that allows the functions to communicate and cooperate with each other. Evaluation of the prototype takes place in five independent case studies, in which the potential of the cyber-physical implementation is demonstrated by a successful system-internal cooperation. The study found that important aspects of cyber-physical systems, like their embedded control, the integration of actuators and sensor networks, implementation of a communication system and connection to a digital twin, are also feasible and promising in the façade domain.

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Additive Manufacturing (commonly known as 3D printing) technology has become a global phenomenon. In the domain of heritage, 3D printing can be seen as a time and cost-efficient method for restoring vulnerable architectural structures. The technology can also provide an opportunity to reproduce missing or destroyed cultural heritage or to express lost appearances, in the cases of conflicts or environmental threats. Researchers from TU Delft have led two experimental projects published respectively in Innovative Materials (volume 6 2018 and volume 1 2019). The projects show the challenges and possibilities of contemporary 3D printing technology for the 3D printing of heritage. The first one, a 4TU-project called ‘Re-printing architectural heritage’ focused on the Hippolytuskerk in the Dutch village of Middelstum. There, the group of researchers tested available technologies to reproduce a mural on a section of one of the church’s vault with maximum possible fidelity to material, colours and local microstructures. Simultaneously, a second project was conducted at the Mauritshuis at The Hague. This to investigate and to discuss the potential of reprinting historical spaces as a copy.@en