Façade engineering is facing an era of extraordinary challenge to meet the surge in demand for buildings that are environmentally sustainable and enhance occupant wellbeing. Facades, also known as building envelopes, play a major role in the resource-efficiency of buildings and the quality of its indoor environment. Consequently, the development of effective design approaches is crucial for generating appropriate façade solutions. Façade design is complex and multi-disciplinary involving several and oftentimes conflicting performance criteria. Systematic and holistic design procedures are, therefore, required to achieve optimal trade-offs. Over the last decades, researchers in this field have used computational tools and power to address this challenging problem within the context of multi-criteria design approaches. This paper reviews the existing research in this field, and presents the state-of-the-art review from simple to advanced decision-making procedures currently used at the early design stages, where decisions have a disproportionally large impact on the façade performance. The paper provides a complete description of the design variables and objectives typically involved. Alternative multi-criteria design methodologies regarding discrete decisions and automated optimization are reviewed, each with salient pros/cons, and overall conclusions are drawn. Finally, the paper discusses ongoing trends and research needs, namely, the development of uncertainty-based procedures to enable more informed decision-making; the inclusion of structural/seismic safety considerations in the design process to achieve higher socio-economic benefits; the integration of smart building information modeling and processing technologies to facilitate smarter design decisions; and the adoption of integrated design approaches to promote climate-adaptive solutions that enhance resilience.

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The adaptive control of sunlight through photochromic smart windows could have a huge impact on the energy efficiency and daylight comfort in buildings. However, the fabrication of inorganic nanoparticle and polymer composite photochromic films with a high contrast ratio and high transparency/low haze remains a challenge. Here, a solution method is presented for the in situ growth of copper-doped tungsten trioxide nanoparticles in polymethyl methacrylate, which allows a low-cost preparation of photochromic films with a high luminous transparency (luminous transmittance T_lum = 91%) and scalability (30 × 350 cm²). High modulation of visible light (ΔT_lum = 73%) and solar heat (modulation of solar transmittance ΔT_sol = 73%, modulation of solar heat gain coefficient ΔSHGC = 0.5) of the film improves the indoor daylight comfort and energy efficiency. Simulation results show that low-e windows with the photochromic film applied can greatly enhance the energy efficiency and daylight comfort. This photochromic film presents an attractive strategy for achieving more energy-efficient buildings and carbon neutrality to combat global climate change.

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Circularity for Educators’, and a second platform for interaction and direct exchange that we call ‘Educators for Circularity’, are part and parcel of the Circular Impulse Initiative (CII), a project intending to enhance the integration of circularity in BK education. Whereas the first provides with content on either circularity or pedagogy, the latter offers the opportunity for all of us to meet and share our experiences and learn from one another. More than 40 professors and researchers have contributed so far with videos and additional resources that are open and accessible to all. @en

For the past years, the Faculty of Architecture and the Built Environment of TU Delft and in particular, the Circular Built Environment (CBE) Hub, have been systematically involved in research related to how the concept of circularity affects and is affected by the built environment. But how can the input of this research be organically integrated into the faculty’s education in order to inspire students and educators towards adopting circular principles? Two major challenges emerged: the first was relating the research findings in one consistent narrative and translating the research input into communicable knowledge. The second, was developing novel pathways for teaching circularity and most importantly, building the capacity of the school’s educators to support students in their learning.@en

Introduction: The challenge of the energy transition in the built environment has, in recent years, been exacerbated by rising awareness of the material resource limitations we face on the path towards sustainable development. In this context the concepts of Circular Economy (CE) and Product-Service Systems (PSS) have emerged as potentially complementary industrial and business strategies to overcome the interdependent material resource and clean energy challenges. Research significance: Research in the field of circular and PSS-based construction frequently centres on the design and engineering of products, mainly through technical strategies such as design for disassembly and adaptability, and the use of the different “R’s” (Reuse, Repair, Remanufacturing, etc.) to extend and/or reset the service lives of building materials and components. Such an approach often ignores the fact that these strategies require changes in the management, financing, and governance aspects of products and therefore buildings, throughout their entire service-lives. This paper will focus on the systemic administrative (i.e. management, financing, and governance) challenges of the circular and servitisation transitions in the building and construction sector, to enable products which are “Circular by Design”, to effectively support regenerative processes. Research question: The paper asks how traditional building products’ management, financing, and governance processes prevent or delay the implementation of CE and PSS models. It explores the demand side’s perspective (commissioners, building owners and facility managers), taking a systemic view to the search for new practical, strategic, and scalable administrative models. Methodology: The research method applies the DAS model (De Jonge et al., 2009; Van der Zwart et al., 2009; den Heijer, 2011; den Heijer et al., 2016) to data gathered from focus group discussion and co-design sessions involving multidisciplinary teams of experts from both academy and industry, as well as literature. The research was conducted within the context of the TU Delft Facades-as-a-Service full-scale pilot project. Results: The research has shown that, while PSS models to enable material circularity can be partially implemented within the current managerial, financial, and governance framework, this implementation is not efficient, effective, or scalable. This is because standard modes of operation in these disciplines are misaligned with that goal. The practical barriers resulting from this misalignment increase the complexity, risk perception, and therefore cost of PSS alternatives, and thus prevent their organic adoption despite increasing market interest. Recommendations are made for policymakers, financiers, suppliers, and building owners to overcome these barriers.@en

Solar cooling integrated façades (SCIFs) have the potential to reduce primary energy consumption for space cooling. Identifying key enabling factors in the context of technical and product (T&P), financial (F), as well as process and stakeholder (P&S) related aspects represent an important step providing relevant knowledge for implementing solutions supporting the widespread application. This study aims to identify main factors enabling the widespread integration of SCTs in façades from the point of view of various professionals. An interview guide was designed to tackle main aspects to be considered for supporting the widespread application. Different criteria were considered to select the interviewees during the data collection, such as participants who worked on the application or façade integration of solar/SCTs in buildings. The findings obtained from a total of 23 interviews revealed that the most frequently mentioned factors are product performance and efficiency, facilitating the delivery of product information to architects and clients, aesthetical acceptability, multidisciplinary teamwork, and ability to customize products. The factors were mapped in the context of façade design and construction processes to establish a matrix for implementing solutions in product development. Majority of the factors were linked to the design phase according interviewees’ perceptions. The results also indicated that newly built office buildings have been perceived to be one of the most relevant types of buildings to be considered for such technologies. The identified enabling factors and prospects of future applications of solar cooling integrated facades (SCIFs) contribute to expand the boundaries of knowledge in the field of building product development.@en

In the façade sector, the ecological and circular transition requires the adoption of new business models that exploit the value of the material as much as possible. In this context, the Internet of Things (IoT) is identified as a potential innovation driver for the widespread use of circular approaches. The aim of the paper is to clarify the role of IoT in enabling five circular business models in the façade sector. The potential benefits of an IoT-based façade system are highlighted through a matrix underscoring the relationship between information produced and key actions to achieve the innovative business models. The research discussion and findings open the debate on the perspective of digitally integrated building components.

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Traceability is considered a crucial requirement to enable Circular Economy (CE). Product and process life-cycle data can facilitate circular asset management preserving the asset's value over time and reducing resource consumption. Many scholars point out how the loss of traceability data, lacking information reliability, and unstructured data are still barriers to the widespread application of CE. In the building façade sector, an increased interest on traceability is dictated by a growing demand for environmental product certifications. However, these aspects are often limited to collect data at supply chain stage, thus neglecting a huge amount of information produced during the asset service life. To foster an accessible and life-cycle oriented asset traceability, this research investigates the Internet of Things (IoT) as a potentially disruptive technology for supporting information management. The objective of this work is twofold: (i) to identify what façade life-cycle information is needed to promote CE and (ii) to clarify the enabling role of IoT in tracking, storing, and sharing such information. Through a scoping review combined with interviews to professionals, a theoretical framework structured on four key elements (stakeholders, information list, information management tools, and IoT) is proposed to fill the literature gap and support façade industry in the circular transition. Further research will have to be conducted to face the digital-physical integration issues and develop business models able to fully exploit traceability information value.

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This paper introduces a methodological framework to integrate circularity in architectural curricula and the building blocks that led to its conceptualisation. The first block (Part A) examines how complexity has affected learning and architectural education, in particular. The paper departs from the notion that knowledge produces further uncertainty in conditions of critical complexity. Moreover, the highest levels of complexity require the least scientific of approaches. It then examines the main challenges resulting from this shift: one is that learning identifies with individuals’ ability to make informed decisions and is now conceptualised as actionable knowledge. Second to that, education should opt for a pedagogy that can support learning through decision making. Architectural education, in particular, should be able to foster a new type of professionalism, where individuals assume accountability for their design decisions that extends beyond the aesthetic realm. But what can drive curricula to become more responsive to the current environmental, social, and political realities? The second block (Part B) looks into the issue of circularity. It examines its relevance to architectural education for its potential to function both as an operational scheme as well as a value system. Furthermore, being a concept in the making, circularity can benefit from academic research but can also support a pedagogy that focuses on helping students learn how to learn. The proposed methodological framework (Part C) builds on these two blocks and on the faculty’s research on circularity to develop a scheme of what constitutes content for teaching circularity, how the goals for integrating it into the curricula can be formulated, and what type of pedagogy is suited to support the integration. @en

The type of glazing implemented in a building plays an important role in the heat management of a building. Solar heat entering through glazing causes overheating of interior spaces and increases building’s cooling load. In this work, the energy saving potential of window films based on Cholesteric Liquid Crystals (CLC) is explored. This emerging technology allows for the fabrication of static and thermochromic solar heat rejecting window films and can provide a simple renovation solution towards energy efficient buildings. Simulations on a model office showed that static CLC-based window films can save up to 29% on a building’s annual energy use in warm climates. In climates with distinct summer and winter seasons, static solar heat rejecting windows films cause an additional heating demand during winters, which reduces the annual energy savings. In these climates, the benefit of thermochromic CLC-based window films becomes evident and an annual energy saving up to 22% can be achieved.@en

The servitisation of the built environment, through the implementation of product–service systems, is considered a promising business strategy to achieve a circular economy transition. This servitisation faces a number of practical challenges, among them the technological readiness and effective integration and application of existing and emerging products, manufacturing processes, and digital monitoring and management tools. The research builds on targeted literature review, and on a research-through-design approach based on full-scale pilot projects developed in an ongoing feedback loop between researchers, planners, and industry partners representing both the demand and supply sides of the façade industry in the Netherlands. The paper analyses the technical implementation challenges currently preventing the façade industry from adopting performance-based contracts. It then proposes the roles that existing and emerging digital design and engineering technologies, manufacturing processes, and asset management systems can play in the development, implementation, and fulfilment of such contracts. The paper proposes a multi-stakeholder, systemic model for the development and application of façade technologies capable of overcoming many of the technical implementation barriers to the delivery of performance-based contracts for integrated facades. From this it concludes that an effective development of building technologies should strategically align with the solving of economic and contractual challenges such as circularity-readiness, profitability, risk distribution, legal demarcation, performance monitoring, and residual value stewardship. The resulting framework provides a strategic and conceptual basis for the development of circularity-enabling façade technologies, accounting for the diverse and sometimes conflicting interests of the multitude of stakeholders involved throughout a project’s lifecycle. The framework aims to support planners, manufacturers, and builders accelerate the circular deep energy renovation of the built environment while also exploring new business opportunities.@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

This paper discusses the relevance of academia in addressing complex contemporary issues and more specifically, its potential to help society transition to a circular built environment. Can academia provide society with a safe space for developing imaginaries and socially performing alternative political futures? Can it help reconnect the many knowledge domains that appear now to be dispersed and fragmented? And what is the role of adult learning in achieving this transition and in dealing with complex issues such as sustainability? The typology and goals of adult educational modules developed by the Faculty of Architecture and the Built Environment of TU Delft and in particular the Circular Built Environment (CBE) Hub are presented here as a response to the growing need of creating synergistic alliances between academia and the rest of society. Three different typologies are examined in this chapter for their specific contribution in raising awareness; inspiring professionals and instigating change in attitudes as well as contributing to the training of selected groups of stakeholders respectively. Authors reflect on the benefits of such interaction, its limitations as well as its future potential. Promoting the benefits of transitioning to a circular built environment and reaching the widest audience possible to assist with the transition requires that academia develops new educational formats. Attention should therefore be given not only to the content produced, but also to the modes of delivery; the effectiveness of the message that is ultimately delivered as well as the establishment of a continuous presence where different individuals or groups can return to when challenged by complex issues. Consolidating this relation can close the knowledge gap between the two: on the one hand society directly benefits from academic research, on the other hand, academia becomes more relevant for society.@en

The regulatory drive to accelerate the clean energy and circular economy transitions in the European building stock is currently failing to overcome systemic implementation barriers. These barriers include high initial investment costs, misaligned financial incentives among stakeholders, and the relatively low cost of less sustainable energy and materials. A Product-Service Systems (PSS) approach could successfully overcome many of these barriers by (1) outsourcing capital investment, as well as financial and technical risks, (2) providing shared economic incentives to collaborating stakeholders, and (3) retaining extended producer responsibility and ownership over materials and products. However, PSS is still not seen as a viable business model when compared to both a standard “ownership” contract and a “no-retrofit” scenario. This paper proposes a Total Value of Ownership (TVO) method to evaluate the financial performance of a building energy retrofit in terms of Net Present Value, comparing a matrix of scenarios. Results show that – when accounting for capital and opportunity costs tied to alternative investments, internalising externalities, and monetising soft values such as user productivity and property value – a PSS model can deliver the highest NPV. Furthermore, results show that a PSS alternative can act as a positive future-proofing strategy to safeguard the building owner’s position in the face of uncertain future market indicators and carbon taxation. Recommendations for policymakers, investors, financiers, building owners, and end-users are presented to identify the economic value of PSS contracts, leading to better-informed decisions which can accelerate deep energy retrofit of the building stock.@en

Unitized curtain walls are glazing facade systems widely used in modern architecture for mid and high rise buildings, due to their benefits in terms of lightness, quality control, ease of construction and quick installation. However, recent earthquake surveys have shown damages to these non-structural elements. Slight-to-moderate damage can cause loss of facade functionality, moderate-to-major damage can provoke severe post-earthquake economic losses and pose a life-threatening danger to both building occupants and pedestrians. Despite recent studies on the seismic behavior of unitized curtain walls, research in this field is still limited and experimental investigations typically neglect the study of the overall facade performance as well as the identification of the full sequence of damage states and the ultimate resistance of the facade components. This paper presents the extensive experimental campaign carried out at the laboratory of Permasteelisa Group, in Vittorio Veneto (Italy), to investigate the seismic behaviour of full-scale unitized curtain walls from a holistic and multi-performance perspective. The research aims at providing information about the serviceability performance and the ultimate limit state of alternative facade designs. The tests involve various facade configurations consisting of dry (gasket) vs. wet (structural silicone) glazing systems with different construction details for glass, frame and joints (dimensions and type). The testing sequence consists of displacement-control dynamic cyclic loading and/or time histories at increasingly seismic intensity levels, accounting for in-plane, out-of-plane and vertical movements. Air infiltration tests, water leakage tests and wind resistance tests are performed before and after the low-intensity seismic tests to study the post-earthquake facade serviceability. This paper discusses the research objectives, the specimen details and the test setup, and provides preliminary experimental results.@en

Als gevolg van een wereldwijd groeiende bevolking en de behoefte aan comfortabele en gezonde binnenomgevingen, ligt er een enorme bouwuitdaging in het verschiet met de ontwikkeling van nieuwe bouwprojecten en de noodzaak om de bestaande gebouwenvoorraad te upgraden. Om te zorgen voor een toekomstbestendige, duurzame economie voor toekomstige generaties is het terugdringen van het gebruik van primaire hulpbronnen essentieel. Er is dan ook nood aan een verschuiving van lineair naar circulair ingerichte systemen. Circulariteit is gericht op het vernauwen, vertragen en/of sluiten van materiaal-, water- en energiestromen (Bocken et al. 2015).@en

Researchers have reported that despite technological development in photovoltaic technology and substantial cost reduction, there is still a narrow interest in architectural photovoltaic applications (APA). Lack of interest is correlated to various bottlenecks, and one of them is a lack of knowledge among architects on the possibilities and approaches to adopt APA. In response to the issues mentioned, the aim of the research presented was collecting qualitative and quantitative information from architects as lessons learned and perceptions in regards to APA. In total, 30 architects with and without experience of using photovoltaics (PV) were invited and interviewed. They were asked about their experience, design and decision-making process with PV, their understanding of integration, and the decisive factors to use APA. The results showed apparent differences between the experiences and perceptions, and they highlighted the lessons learned from realized projects. The analysis of the visual implication of PV integration shows that, to the eyes of architects, integration of PV into architecture does not depend on the PV product used, but instead, that when PV is part of the design concept and design process, the outcome is seen as a meaningful integration. @en

Incentivising investment and long-term collaboration in high-performance facadeprojects. This technical report is an annex to the Facade Leasing Demonstrator Project 2019 performance report(2.7.3.FLD.D1). For general information on the Facade Leasing research project, its process, and objectives please refer to the aforementioned document. This technical delivery report focuses on the economic and business model aspects of the FLD project. The innovation behind the Facade Leasing research project lies not so much in the creation of new, energy-efficient facade technologies, but rather the creation of new investment and management processes leading to amore widespread and effective use of available and upcoming technology. The present report starts by describing the large, and growing, market for economically feasible facade renovation solutions. The research presently focuses on the Dutch non-residential, (semi-)publicly owned market, which has been identified as an ideal early adopter, but extrapolations are made to other European segments in the “Upscaling” chapter. The report then presents the work done by the research and practice consortium of the FLD project, represented by real estate owners/operators, facade fabricators, financial institutions, and other key stakeholders towards the definition of a promising business and financial model for the contracting of Facades-as-a-Service.@en