Rising temperatures are leading to an increase in cooling energy demand and thermal discomfort due to overheating. Despite dynamic switchable glazing being a promising solution for controlling solar radiation while preserving user access to outdoor views, their cost is currently a barrier to their widespread adoption. The recent development of low-cost inkjet-printed switchable glazing offers a cost-effective alternative; however, its performance remains uncertain concerning its contributions to energy efficiency and user satisfaction in terms of thermal comfort and visual experience. This study presents a multi-domain evaluation of the performance of a novel low-cost inkjet-printed glazing with users in terms of their satisfaction with the environment, personal control and interaction. In comparison to a conventional façade with static glazing and external roller blinds, the EC glazing performed better than the conventional façade if the shading is fully down. In this case, higher satisfaction was measured in terms of view clarity, daylight access and colour in the room with the EC glazing. When comparing the performance of the EC glazing at the clearest state with conventional glazing with blinds raised, users’ satisfaction was not significantly different, except for the satisfaction with view clarity. Despite the long transition time of the EC glazing, users were not significantly dissatisfied with the speed of transition. Overall, these preliminary results show that this novel EC glazing is well-accepted by users especially as an alternative to traditional dark roller blinds, but further research is required to investigate its performance during summer.

The increasing frequency and intensity of heatwaves raises questions about the thermal vulnerability of buildings and, in particular, on how to assess their resilience to extreme heat. In this context, thermal fragility curves, which describe the probability of achieving or exceeding specific temperature thresholds for a building, serve as an effective measure to define the thermal vulnerability of existing buildings and identify tailored retrofit strategies. This study focuses on deriving thermal fragility curves for a case study: a 6-storey residential building constructed in the 1980s with a reinforced concrete structure and masonry infill walls. Dynamic thermal modeling and simulation were conducted over a one-year period using synthetic weather files generated to account for future heatwaves. The simulation results provide useful relationships in particular between: outdoor temperature and indoor Standard Effective Temperature (SET); and between outdoor daily maximum temperature and indoor SET. These relationships were finally analyzed to create and compare fragility curves using maximum likelihood fitting and the so-called Cloud methodology.

Achieving a climate-neutral European Union requires overcoming challenges in Nearly Zero-Energy Building (NZEB) renovations, including labour shortages and time-intensive traditional methods. Industrialised façade systems offer a promising solution, but their life-cycle impacts remain insufficiently studied.

This research uses life-cycle assessment to compare conventional and industrialised façade systems for renovating a representative residential building typology. Renovation scenarios integrating passive, active and renewable measures were analysed to assess embodied (A1–A5, B4) and operational (B6) carbon emissions. Results show that façade renovations can reduce total carbon emissions by 44 % (industrialised) and 58 % (conventional systems) compared to the current state. Additionally, large pre-fabricated panels significantly reduce construction waste, while modular façades with integrated photovoltaic panels exhibit the highest circular economy potential.

The findings of this study enhance the understanding of industrialised façade systems across their life cycle, highlighting their potential to accelerate NZEB renovations while addressing key barriers to scaling decarbonisation efforts across Europe.

Rising temperatures are leading to an increase in the cooling demand of buildings. Electrochromic (EC) glazing can be a promising solution for controlling solar heat gains while maintaining outdoor views. This paper presents the results of the monitoring of prototype panels of a novel type of inkjet-printed EC glass under real use and weather conditions in a small office building in the Netherlands. This building contained two identical west-facing meeting rooms of which one was equipped with EC triple glass IGUs and the other with normal triple glass IGUs. Each room was equipped with local heating/cooling units of which the energy use was monitored, and with an extensive environmental sensor network. Sensor and calendar data was fed into an energy balance model for each of the rooms for the entire measurement period, allowing to correct for differences between the two rooms with respect to heat losses and gains and use conditions. The results of the monitoring showed that in the meeting room with EC glass IGUs, the heating demand increased by 34% in Jan.-Mar. 2024 while in Sept. 2023 the cooling demand decreased by 3%. The main reason for the increase in heating demand was found to be the lower g-value of the EC glass IGUs in clear state as compared to the normal IGUs. The almost similar cooling demand was a result of a trade-off between the lower direct solar transmittance of the EC glass IGUs and the heating up of the absorptive layer inside the IGUs. Furthermore, an experiment with participants showed that in general in dark state, satisfaction with view clarity, daylight colour and daylight availability was higher for the EC glass IGUs. In transparent state, no significant difference was perceived between the EC glass IGUs and standard IGUs, except for view clarity.

To reduce material waste and carbon emissions, the manufacturing industry of exterior window frames (aluminium, PVCu and timber) could transition from recycling to remanufacturing. This paper investigates to what extent reclaimable window frames from 1970 to 2010 are technically upgradable to meet current thermal and airtightness requirements, and if the existing (linear) supply chains are able to perform these upgrades. To answer these questions, a multi-method approach was used. Historic window frame designs were retrieved from standard literature. These were assessed to see what minimum upgrades they require to comply to current regulations. Retrieved process models of the existing supply chains were then used to investigate to what extent the existing factories are able to perform these upgrades. The results show that based on the assessed historic window frames, it is possible to upgrade aluminium, PVCu and timber window frames of around 25 years old, depending on the window size. However, from a remanufacturing perspective, all three existing supply chains lack essential steps to perform these product upgrades. Also some existing manufacturing processes can't be used for remanufacturing, as they are designed to process unencased, individual profiles. This makes reclaimed encased frames incompatible with the first processes of the linear supply chains. PVCu and aluminium profiles are manufactured in respectively two and three factories, which is a notable impediment for re-finishing the profiles. Two identified opportunities for upgradability and remanufacturing are standardization of interfaces and modularity. Future multi-lifecycle circular window frame designs could benefit from further implementation of these design approaches.

The transition towards a circular economy in the built environment requires robust methodologies to evaluate carbon and material flows at the component level. This paper introduces Carbon Flow Analysis (CFA), an innovative approach that integrates Material Flow Analysis and Life Cycle Assessment to facilitate environmental decision- making for façade renovations. CFA systematically maps embodied carbon and material inputs within façade components, offering a transparent assessment of their circularity potential. The study further refines the selection process through a contextualization framework, which contrasts CFA results against environmental performance ranges derived from Environmental Product Declarations (EPDs) and environmental databanks. Findings demonstrate the variable role of secondary materials in reducing carbon emissions, due to the large variability of impact across materials and components. While CFA provides actionable insights into material selection for façade components, the study highlights the need for standardized circularity indicators and reliable databanks to enhance decision-making in architectural design. By combining quantitative carbon tracking with performance- based contextualization, this research contributes to the development of practical guidelines for achieving carbon-neutral façade renovations.

Justice-oriented, context-sensitive approaches that go beyond technocratic top-down decision-making processes can facilitate and improve the retrofit and energy transition of housing. Urban living labs (ULLs) are emerging as valuable collaborative spaces for learning and co-creating strategies. Although increasingly adopted in urban planning and placemaking, their potential to operationalise procedural justice by facilitating inclusive and accessible processes in energy renovation remains unexplored. Drawing on fieldwork notes and expert interviews, this study examines the initial phases of four Dutch energy living labs (ELLs) implemented in vulnerable neighbourhoods to support housing retrofit and energy transition projects. It analyses how they foster residents’ inclusion and connect institutional agendas with residents’ everyday practices and living environments. The findings reveal how ELLs play a strategic role in enhancing residents’ visibility, creating multistakeholder relational arenas that stimulate interorganisational learning. Researchers in ELLs mediate between theory and situated practices, facilitating energy justice implementation by challenging established professional assumptions. Flexible, locally guided forms of ELLs help address process shortcomings, supporting more socially embedded retrofit and energy transitions, and notably contribute to a) resident engagement and representation, b) technical design and performance and c) collaborative and responsive governance approaches.

Energy renovation of residential buildings is a key strategy for a just energy transition, involving complex socio-technical challenges and increasingly requiring attention to social implications and equity. However, what constitutes just energy renovations remains undefined and often limited to more abstract conceptualizations, lacking a field-specific definition, with integrated, implementation-oriented guiding strategies. Limiting the scope to developed countries, this study systematically reviews 104 interdisciplinary studies on energy renovation that consider social and resident dimensions. The literature is analysed through a synthesised framework of energy and spatial justice theories, adapting the principles of recognition, procedural, and distributive justice to residential environments and energy renovation requirements. Firstly, the study provides a comprehensive overview of socially oriented renovation research, demanding greater attention to vulnerable contexts, stakeholders' dynamics, design and post-renovation phases, through iterative, co-creative field research. Secondly, the study identifies critical domains, subdomains and related (in)justice trajectories within the three justice principles, offering context-sensitive application pathways and highlighting the relevance of beyond-energy-efficiency aspects and trust-building strategies. This results in a flexible framework of decision-making criteria that align environmental and social needs, supporting researchers, policymakers, and practitioners. Achieving justice requires interconnected mechanisms across decision-making levels and renovation phases, that rely on collaborative mutual-learning dynamics among actors. To complement strategic policies, design and implementation criteria emerged as crucial for ensuring effective engagement and user-centred interventions. This study contributes to validating energy justice as a decision-making guide, demonstrating the added value from spatial justice integration for a just urban transition, and laying fertile ground for further empirical research.

Integrating solar cooling technologies into building façades can play a crucial role in reducing reliance on conventional cooling systems. However, incorporating various aspects at the early stages of a project can be challenging for designers due to the diverse types of information, steps, and decisions required. This study aimed to develop strategies for design teams to facilitate the early-stage design and evaluation of building façades integrating solar cooling technologies. The strategies were developed using a research-through-design methodology, considering the Spanish context and a proposed evaluation set-up to assess techno-economic feasibility. The development of strategies involved mapping the design and evaluation of solar cooling integrated façades by identifying and relating key processes, inputs, outputs, design decisions, and tools within key design stages. Consequently, a systematic design and evaluation process was carried out, including the identification and assessment of potential integration scenarios for solar electrically driven and thermally driven technologies based on relevant techno-economic criteria. The findings indicate that water-cooled vapor-compression chillers (VCC), combined with photovoltaic (PV) panels as an electrically driven solution, were the most relevant option for the selected case. Additionally, the developed strategies revealed that early-stage decisions significantly impact later processes, as they involve a greater number of steps, required information, and design choices. These strategies serve as guidelines to support designers in adopting a systematic design approach, helping to manage the complexities associated with processing diverse technical and economic information. Providing such structured methodologies to professionals with limited experience in solar cooling technologies is crucial for enabling their broader application.

Research into the impact of innovative sustainable energy experiments and demonstrations is crucial to diversifying, scaling up, and accelerating the sustainable energy transition. Although there is vast research into sustainable energy experiments and demonstrations, research literature offers a fragmented collection of findings. A coherent overview of themes and insights regarding the transformative impact of innovative sustainable energy experiments and demonstrations on sustainable energy systems from the past, present, and near future is lacking and necessary to increase experiments and demonstrations' impact on the sustainable energy transition. The research in this study fills this knowledge gap by providing such an overview and yields novel insights into the organized function and impact of experiments and demonstrations. It spans a broad spectrum of sustainable energy technologies, the empirical domains where these are invented, developed and applied, and the stakeholders involved. The overview is the outcome of a Delphi study in which the insights of 47 international scientific research experts in sustainable energy experiments and demonstrations are bundled and explained. This study presents a thematic overview of the significant insights regarding past and current sustainable energy experiments and demonstrations and outlines a research agenda for the future. Policymakers, practitioners, and scientists can leverage this to inform their sustainable energy policies, business strategies, and research programs.

Given the global challenges arising from climate change, relevant, promising methods to expedite the energy transition are essential. The integration of solar cooling technologies into façades represents an important option. Potential benefits of applying solar cooling technologies include conserving primary and conventional electricity sources, lowering peak energy demand to achieve cost savings, and offering environmental benefits. This study aimed to support the design team and stakeholders involved at the design and development stages with a framework that supports developing solar cooling integrated façades. This study adopted a participatory research methodology to identify, outline, and validate key decisions, information, and stakeholders supporting product design and development. The key study findings revealed that the integration of solar cooling technologies into façades should be considered at the conception stage, where the client, climate designer, building physicists, building service consultants, and architects were identified as key participants who should be involved in the decision-making process. The most critical information identified for supporting design decisions includes technology costs, performance and efficiency, cooling demand, and construction characteristics of the thermal envelope.

In the early stages of building renovation projects, the lack of information on the existing building and an unclear definition of project objectives have been identified as critical bottlenecks. An early decision support tool has been developed to mitigate or overcome these barriers. The tool provides initial estimates tailored to the specific building and climate being assessed, and can be used to guide the renovation design at an early stage, even from very limited information. It includes the automatic generation of potential renovation scenarios, a dynamic energy simulation of existing and renovated cases, integrated economic and environmental assessments from a life cycle perspective, and a multicriteria analysis that ranks renovation alternatives to meet the interests of the stakeholders involved. The user obtains an initial indicative budget and the expected potential benefits of several renovation projects over comfort, energy consumption, economic cost and environmental performance. One of the main assets of the tool is the reduction in time and cost at initial phases of the renovation process, avoiding the need of site visits and the use of more laborious simulation tools.

Roughly 97% of the European Union (EU) building stock is not considered energy efficient, and 75–85% of it will still be in use in 2050 (Artola et al., Boosting building renovation: What potential and value for Europe? 2016). Residential buildings account for around two thirds of final energy consumption in European buildings. The rate at which new buildings either replace the old stock or expand the total stock is about 1% per year. Similarly, the current renovation rate of existing buildings in the EU is about 1–2% of the building stock renovated each year. Renovation strategies on building levels need to be derived from a combination of energy efficiency upgrades to buildings and the use of renewable energy to decarbonize the energy supply, on a district or city scale. IEA EBC Annex 75 subtask D2 focuses on promoting cost-effective building renovation at district level combining energy efficiency and renewable energy systems, by focusing on the business models that can make implementation possible. This paper intends to provide an overview of the business model archetypes that can support the development of district demand and/or supply of energy-efficient building renovations and/or renewable energy solutions by targeting various types of stakeholders. It builds upon existing literature to gain insights into the current distributed energy business model landscape. Further, implementation strategies are identified that focus on a holistic evaluation of the expected energy and CO₂ performance of the site and optimized infrastructure investment pathways.

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.

In typical practice of building renovation design, distributed teams communicate through technical drawings, but the construction industry lags in digitalization. This study addresses this gap by proposing a methodological framework integrated into digital tools for early-stage renovation processes. The framework, implemented as a web-based tool, gathers user inputs related to building details and preferences to generate alternative renovation scenarios. It utilizes databases for building characteristics, technologies, and life cycle assessment (LCA)/life cycle cost (LCC) calculations. The information flow involves user inputs, database storage, and processing layers, enabling simulations and scenario evaluations. The framework facilitates quick, cost-effective, and customized decision-making in the early design phases, aiming for energy-efficient retrofits. Results highlight the importance of databases, such as building characteristics and LCA/LCC, while emphasizing a clear communication protocol among stakeholders. Overall, the study seeks to accelerate and streamline the renovation process, promoting efficient collaboration and reducing time and costs.

Energy renovation processes in vulnerable neighbourhoods are complex decision-making endeavours. The JustPrepare project aims to develop inclusive strategies attuned to local needs to enhance energy renovation and transition effectiveness, considering economic, environmental, and social benefits.

The renovation of existing buildings is widely recognized as a powerful strategy for reducing emissions and land use. However, when it comes to residential buildings, the socio-technical challenges are particularly complex. The necessity and urgency of increasing energy efficiency often lead to retrofit processes that overlook residents’ needs and fail to consider the impact of renovation techniques on their lives. This study conducts a systematic and interdisciplinary literature review to explore how and to what extent social aspects, particularly residents and their needs, are considered in building renovations. An analysis of 40 studies from the Web of Science and Scopus databases is presented. The holistic overview focuses on two interrelated aspects: the orientation of decision-making processes towards residents and social components of multi-stakeholder involvement, and the relationship and interaction between design choices and residents. By doing so, the review enables a collection of meaningful and heterogeneous criteria for process management and retrofit solutions selection. Recognizing the existing gaps in the literature and clarifying relevant criteria, this review can help identify areas that require further research and intervention.

The construction industry, accounting for a significant portion of energy consumption and greenhouse gas emissions, is pivotal in achieving Europe's ambitious climate neutrality goal by 2050. Circular Economy (CE) principles and the renovation of existing buildings are identified as promising strategies to reduce raw material and energy consumption. However, the lack of knowledge and guidelines for effective CE design and construction in the built environment, along with heterogeneous metrics and standards, pose challenges. The research outlines an investigation study aimed at developing Key Performance Indicators (KPIs) for evaluating building products based on CE principles, focusing on façade renovation. The study emphasizes the need for a holistic approach, considering both material input and output flows, and introduces qualitative and quantitative KPIs addressing aspects such as recyclability, modularity, and local materials. The research proposes established frameworks like Life Cycle Assessment (LCA), Material Flow Analysis (MFA), and the Level(s) framework, but recognizes their limitations in assessing circularity comprehensively. The methodology involves a comprehensive analysis of material streams and circularity potential for nine components crucial to achieving a net-zero façade renovation. Results from the material flow analysis demonstrate the environmental impact of selected building products, such as insulation panels and photovoltaic panels. The research underscores the importance of informed design choices, leveraging adaptable KPIs, and visualizing resource flows to enhance decision-making for sustainable construction practices aligned with CE principles.

The present research proposes a framework to design and evaluate façade products integrating solar cooling technologies (SCTs), applied in an office building in a Southern Europe region. The building comprises various types of façade elements, such as opaque walls, glazed curtain walls, overhangs, and balconies. Key regulatory measures were implemented considering national energy saving regulations. The results represent annual energy consumption (kWh/m2/year) and the average daily cooling demand in Summer Design Week (kWh/day) of the simulated base model. This energy consumption lies within range of a previously simulated generic office and the average annual energy consumption of office blocks. Potential scenarios for integrating SCTs were outlined and evaluated using the solar fraction (SF) as an indication to measure the potential performance of the system based on nominal efficiencies, providing an initial reference of its ability to meet cooling demands, an essential step in early design stages. Scenarios per configuration related to double-effect chillers with evacuated tubes collectors and water-cooled vapor compression chiller and photovoltaic (PV) panels were the only one having an SF value of 1 or more, meaning that they can be able to handle the required cooling demand. Future steps should consider a second level of technical evaluation of scenarios having SF values of 1 or more, which should involve aspects related to how to physically integrate the technology, considering compactness and space usability and also maintenance requirements, among other relevant criteria.