Especially in underprivileged neighbourhoods (UNs), with high renovation urgency and thus opportunities to kick-start the energy transition (ET), residents tend to resist retrofit measures. This is due to general lack of trust in government, housing corporations, and other key players. We contend that a negative spiral of ET effectiveness and justice is rooted in two mismatches, between (i) UN resident needs and everyday practices and customary ET solutions and between (ii) UN residents and the key players running the ET. This may produce a downward spiral of ineffective solutions, declining trust and inequalities. We argue that fundamentally addressing these mismatches may reverse this downward spiral into an upward one, and then present our Just PREPARE approach to that challenge. At the core of this approach are (i) ‘double-eyed’ methods to help articulate residents' needs and practices in their own context, which then inform the design of the technological and governance aspects of solutions and (ii) participatory settings and processes for planning the ET. We elaborate this approach and present some illustrative preliminary experiences from a transdisciplinary research project in which we implemented it in four UNs in the Netherlands. We end with some recommendations for future research.

Transitioning existing dwellings to lower temperature heating (LTH) is crucial for achieving the Dutch goal of making 1.5 million homes gas-free (i.e., independent of natural gas-based heating) by 2030. This transition often necessitates energy renovations, which present significant decision-making challenges in selecting appropriate solutions. Consequently, this study introduces a systematic framework based on multi-criteria decision-making (MCDM) approach to support selecting suitable renovation options for preparing Dutch dwellings for LTH supplied by sustainable heating systems. The framework is methodically developed by generalising typical steps from existing literature and identifying essential decision-making aspects for framework development. It was then theoretically tailored to the specific context of LTH-ready renovations. The framework involves six steps: data collection and benchmarking, evaluating LTH readiness, establishing decision-making preferences and generating renovation solutions, filtering LTH feasible options, quantifying their performance, and ranking them using the TOPSIS method. Furthermore, the theoretical framework was applied to a case study of a multi-family social house (MFH) in the Netherlands to demonstrate its practical usability and to incorporate real-world context in decision-making. While the framework's applicability has been validated for this specific case, further application across different contexts is necessary to generalise its usability. The proposed framework comprehensively evaluates renovation solutions needed to transition to LTH based on environmental, economic, and social criteria, thereby addressing energy poverty and occupant comfort concerns. This supports stakeholders in making informed decisions and accelerating energy renovations for a decarbonised built environment.

Districts face dual pressures: reducing carbon emissions while managing surging electricity demand from electrification and urban growth. Traditional grid expansion cannot match the speed and complexity required for modern energy transitions. District energy transitions require connecting different scales, from individual buildings to grid networks, and different timeframes, from daily operations to long-term planning. Despite growing interest in Digital Twin (DT) for energy management, their application to integrated district-level energy transitions remains poorly understood. This review investigates how DTs can enable district energy transitions by examining their applications in built environment and energy infrastructure at district level, analyzing implementations across Positive Energy Districts (PEDs), microgrids (MGs), and related district energy paradigms. DT components (physical models, core capabilities, data infrastructure, and functional evolution) are investigated to assess their integrative potential. The analysis reveals three disconnects: building and grid systems are modeled separately despite inherent interdependencies; operational insights rarely inform infrastructure planning; and intervention strategies overlook sequential dependencies. To address these gaps, we propose an integrated framework advancing DTs toward district energy planning. The framework bridges semantic, temporal, and sequential planning through: knowledge graph architectures enabling cross-domain data integration, coupled simulation pipelines capturing building-grid interactions, and reinforcement learning optimizing intervention sequences. Unlike optimization that fixes strategies upfront, sequential planning accommodates technology emergence and regulatory shifts inherent to multi-decade transitions. This integrated approach transforms DTs from domain-specific monitoring tools into strategic planning platforms where coordinated building improvements and distributed energy resources defer costly grid expansions while accelerating district decarbonization.

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.

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.

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.

Current multi-hazard risk approaches in seismic engineering primarily focus on structural performance under hazards such as earthquakes, floods, and wind. Despite the distinct risk due to their direct impact on human health, heatwaves receive limited consideration. This unbalanced and fragmented approach is particularly noticeable in facade retrofit design, which has a significant influence on both structural vulnerability during earthquakes and indoor thermal conditions during heatwaves. In this case, integrating seismic and heat risk considerations would help balance performance trade-offs across both domains and assist designers in the selection and combination of technologies that are effective under seismic and heatwave conditions. This study therefore proposes a simulation-based multi-objective methodology for facade retrofit decision making. The suggested approach is demonstrated through a case study: a reinforced concrete building retrofitted using a timber rocking-dissipative external exoskeleton and precast concrete sandwich facade panels. Key facade design parameters-component capacity and dimensioning-were varied to generate a multivariate response for both seismic and thermal performance. The simulation results revealed two challenges for optimization: a limited sample size and nonlinear relationships between design inputs and performance outcomes. To address both, a multivariate regression was applied within segmented performance ranges, defined by breakpoints where the relationship between parameters and performance shifted. The resulting segmented multivariate model enabled the identification of optimal technology combinations within specific performance ranges and the generation of multiple Pareto fronts. This broadened the viable solution space and better supported project-specific trade-off decisions.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

This study introduces a systematic framework to facilitate decision-making in selecting renovation options for preparing existing Dutch dwellings for utilising lower temperature heat (LTH) supplied by district heating (DH) systems. The framework was applied to an archetype terraced intermediate house built between 1945 and 1975 to identify the renovation options required for transitioning from existing High-Temperature (90/70℃) supply from gas-boilers to Medium Temperature (70/50℃) supply from DH systems. The framework's effectiveness was demonstrated by systematically assessing the readiness of the archetype dwelling for LTH use, reducing the number of viable renovation options, evaluating the financial feasibility using a life cycle costing approach and generating decision support insights through comparative analysis. The framework identified an optimised solution involving cavity wall insulation, exhaust ventilation and switching to low-temperature radiators. This solution incurs low initial investment and global costs while significantly reducing space heating and underheated hours. As a result, the framework provides tangible solutions for the specific use case and can serve as a valuable tool for dialogue among stakeholders during the decision-making process.