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.@en

Shopping centres hold significant energy retrofit potential in the retail sector. However, their complex multi-stakeholder governance structure complicates decision-making for Energy Efficiency Retrofits (EER). Although literature identifies some barriers linked to EER, they are often scattered and not identified within a process perspective that considers their contextual complexities. This study addressed this gap by examining stakeholders’ behaviours, barriers, and relations during EER decision-making processes, to detect stakeholders’ needs to catalyse the energy transition. Qualitative research was conducted on three representative Dutch shopping centres case studies. The cross-case analysis uncovered the decision-making process for EER and new barriers attributed to this building typology. Amongst other, detected barriers can be attributed to limitations with governmental and internal regulations, lifecycle conflicts, proposed interventions being out of scope, and existing technical challenges. The study also revealed causal relationships among stakeholders, showcasing varying interpretations of barriers and highlighting the roles of owners, property managers, and public authorities in overcoming them. Furthermore, the findings indicate the key role that different contextual variables play in the EER decision-making process, such as ownership type, governance structure, and leasing structure. This study offers insights and recommendations for shopping centre owners, property managers, and policymakers, to support them in navigating the energy transition of the retail building stock. Key recommendations include decentralizing decision-making, optimizing governance structure, streamlining sustainability advisors, and acknowledging the collaborative roles of property managers and policymakers in providing effective and holistic solutions.@en

In the context of increasing focus on social sustainability, neighborhood rehabilitation has emerged as a crucial component of global urban renewal initiatives. Distinct from most renewal paradigms that are usually one-offs, neighborhood rehabilitation is a long-term endeavor that requires ongoing resident participation to effectively address diverse needs, investment shortages, and governance challenges. Extant research predominantly focuses on residents' initial engagement, leaving the dynamics of continued participation and its influencing factors largely unexamined. Employing the Expectation-Confirmation Model (ECM), this study explores how residents' initial participation experiences influence their intentions to continue participation. Analyzing questionnaire responses from 367 experienced residents in Wuhan, China, the study finds that a mere 38.2 % of residents exhibit re-engage intention. Path analysis shows that initial participation experience influences residents' re-engage intention indirectly through participation satisfaction and perceived usefulness. Residents' re-engage intention is most influenced by level of influence residents hold in decision-making, followed by type of activities they engage in, and stage of their initial involvement. As an exploratory study into the realm of continued participation, this research uncovers several potential pathways and policy recommendations, aiming to ease residents' transition from initial acceptance to sustained engagement in future neighborhood development efforts.@en

It is recommended to integrate specific management competencies in academic education to support the transition towards environmentally sustainable practices, particularly in the construction and real estate sector. This paper explores how architectural management education can integrate environmental sustainability within its current university programmes. In recent years TU Delft explored and experimented with various education initiatives to bring forward environmental sustainability knowledge and to connect with policy, societal and industry practices. This paper describes what we learned from both bottom-up and top-down initiatives implementing environmental sustainability in construction and real estate management education. Bottom-up educational initiatives show that knowledge about transition policies, stakeholder experiences, business models and management practices from a European perspective can help students across the globe to apply knowledge into their local context, reflecting on the overarching management principals across stakeholders, institutions, academic disciplines and cultures. Top-down initiatives show that the university has a vision on integrating sustainability in its curriculum, but that integrating environmental sustainability in construction and real estate management education is still challenging. Adapting the academic curriculum to integrate building and portfolio responses to environmental challenges might be a way forward and the experiences from numerous elective courses and educational initiatives can be a basis to identify the development of a future standard curriculum.@en

Buildings in the EU consume around 40 % of energy and are responsible for 36 % of greenhouse gas emissions. This necessitates building energy renovations as a coping strategy for energy reduction. Residential buildings consume about 27 % of the energy use in Europe. Multifamily residential buildings, known as condominiums, feature individually owned apartments and are managed by Homeowners’ Associations (HOAs). HOAs constitute a considerable percentage of the owners of the residential sector in Europe. However, the deep energy renovation rate is still low due to the complex process and the barriers faced by HOAs. There is a lack of understanding of the main barriers to undertaking deep energy renovation projects by HOAs and their potential solutions. Therefore, this paper investigates barriers, incentives, and possible solutions that motivate HOAs to undertake deep energy renovation projects. This study employs a combination of qualitative methods, including archival research, the gathering of information through observations at meetings organized by the EU, four interviews, and a workshop with eleven experts. This exploration was conducted from the perspective of three actors: home renovation providers, public authorities, and policymakers in the Netherlands and Flanders. The barriers are grouped under four categories, namely: financial, legal, social, and technical. The findings indicate that communication, cost, and legal structure are the most significant barriers. The incentives play a vital role only in the early phases of the renovation. The findings can inform policymakers, energy practitioners, and researchers in developing targeted strategies for successfully implementing deep renovation projects for HOAs.@en

Socially sustainable urban renewal hinges on active public participation, necessitating effective information sharing. Combining Social Network Analysis (SNA) and Ecological Network Analysis (ENA), this study longitudinally investigates how stakeholder information sharing evolves over the project lifecycle of neighborhood rehabilitation and its impacts on resident participation. A representative neighborhood rehabilitation project in Wuhan, China, serves as the study case, with data from 10 interviews, 35 questionnaires, and 3 focus groups. The study suggests that SNA and ENA are complementary and competent in identifying key stakeholders, as well as uncovering undesirable behaviors of manipulation and monopolization, and unhealthy relationships like exploitation and competition. Implementation unit and neighborhood committee emerged as principal information holders, while local media and tenant were least informed. SNA results underscore the central position of neighborhood committee in collecting and disseminating information, demonstrating significant autonomy and control throughout project lifecycle. Conversely, homeowner showed marked dependence and lacked control, particularly in the planning and design phase. ENA findings reveal neighborhood committee’s ongoing struggle with information exploitation, eroding its willingness and capacity to share information during the later phases of rehabilitation process. The information exploitation led to a fragile network that further marginalized local media, undermined by dwindling trust and autonomy. Notably, homeowners amplified their discourse power as project progressed, shifting from passive recipients to active decision-makers. Yet, well-informed homeowners monopolized information sharing, deliberately excluding others with conflicting interests, intensifying issues of inequity and opacity. Policy recommendations are provided to counter unhealthy stakeholder dynamics and promote equitable and inclusive public participation in urban renewal initiatives.@en

Across the European Union (EU), approximately 46% of the population resides in apartment buildings. A majority of these buildings are in need of energy renovation and are managed by Homeowner associations (HOAs). HOAs face distinct challenges in renovating their buildings. Integrated home renovation services (IHRS) have emerged as a potential solution to accelerate highly energy-efficient renovations for HOAs. The question arises: How do current integrated home renovation service providers facilitate energy renovations for homeowner associations, overcoming the prevailing barriers to uptake? This paper explores the current state of IHRS providers operating in four European regions with a focus on the Netherlands and Flanders. The study offers insights into the dynamics of their business models, strategies, and ways forward. The methods employed involve a combination of qualitative approaches. Fourteen business models of IHRS providers in the Netherlands, Belgium, France, and Austria were analysed, to define their strategies within the regional context. The results reveal that while public entities prioritize broad societal challenges, private models focus on operational efficiency and financial sustainability. Public-private partnerships offer a hybrid approach, blending strengths but requiring precise governance to align diverse interests and achieve comprehensive, sustainable outcomes. The findings can inform policymakers, practitioners, and researchers in developing effective and targeted IHRS initiatives in the EU.@en

Resident participation is essential for neighborhood rehabilitation. It requires the active involvement of residents and efficient management by organizers. To improve the effectiveness of resident participation, it is necessary to understand the critical success factors (CSFs) underlying it. However, previous research has examined the critical factors from a single-stakeholder perspective, overlooking potential differences in perceptions among stakeholders with diverse roles and rehabilitation experiences. Based on 30 interviews and 255 questionnaires from six stakeholder groups in Wuhan, China, this study explores how the perception of critical factors for effective resident participation varies among local government, community-based organization, designer, contractor, consulting party, and resident. Thirty-seven factors were identified and compared among the stakeholders. Financial Incentive (for participation organizers) was identified as the most critical factor for effective resident participation, followed by Information Disclosure and Transparency, and Trust. Results from the analysis of variance (ANOVA) show that the six groups differed significantly in the importance of most factors (25/37), especially in Participant Education and Prejudice against the Working Group. Interview results indicate that the COVID-19 pandemic and rehabilitation experience changed stakeholders’ perceived importance of some factors. Specifically, in future RP initiatives, extra emphasis could be placed on Trait and Capacity (of the working group) and Participation-assistance Technologies. Stakeholders regarded these two factors as more critical as their rehabilitation experience accumulated. By understanding stakeholders' conflicting and changing perceptions of effective resident participation, suggestions were proposed to each stakeholder group to fulfill their distinct participation objectives and improve the overall effectiveness of participation practices.@en

The need for energy efficient buildings has become increasingly important in climate change mitigation. Almost 75% of the building stock in Europe is energy inefficient. Residential buildings are responsible for 27% of the total energy consumption in Europe. Integrated home renovation services (IHRS) have emerged as a potential solution to accelerate highly energy-efficient renovations for homeowners’ associations (HOAs). The question arises: How can the business models of current IHRS accelerate highly energy-efficient renovations by HOAs? This report explores the current state of IHRS in Europe with a focus on the viewpoint of the Netherlands and Flanders. The methods used are desk research, questionnaires and interviews. Five business models (BMs) of CondoReno project partners were analyzed, to support their development strategies within the regional context. This report compares IHRS BMs and brings knowledge about the operation of IHRS. The results show that the BMs of the project partners share some similarities and differ in other aspects. Regarding the similarities, all five providers share the value of offering customized energy renovation packages, also in terms of customer segments, by addressing the specific needs of HOAs. They slightly differ regarding the channels used, customer relationships, key resources, key activities and key partners. They differ in revenue/value streams and cost structure, owing to context-specific aspects of the type of organization. As such, this study informs stakeholders about the development of effective and targeted IHRS initiatives in the EU.@en

This report describes the methodology for identifying and assessing cost-effective strategies for renovating urban districts towards far-reaching objectives regarding reducing carbon emissions and energy use. The report proposes different scenarios considering boundary conditions and different interventions on building envelopes and thermal systems. The proposed methodology builds on the methodology previously developed for individual buildings in IEA EBC Annex 56 (developed by the same main authors of this report), extending it to the level of districts/groups of buildings. Furthermore, it also makes use of results from other related Annexes. The idea is that the methodology supports decision-makers in evaluating the efficiency, impacts, cost-effectiveness and acceptance of various strategies for renovating urban districts, and in identifying suitable renovation strategies. The methodology defines the boundary conditions set for the assessments carried out, the research questions/hypotheses mainly investigated with the assessments, and the type of outputs generated from the assessments. It is intended that, based on the methodology developed, existing tools can be identified, or existing tools can be adapted to support the application of the methodology in case-specific assessments. In addition, an online Calculation Tool (Annex 75 CT) was developed to support the application of this methodology, which is available at: https://annex75.bim.energy and at https://annex75.iea-ebc.org/publications.@en

This report, therefore, focuses on the following objectives:
- Give an overview of various policy options that could target the district level, considering existing and emerging policy instruments with the potential to be successfully applied within that context, and how policy challenges specifically occurring in an urban context can be overcome;
- Develop, test and use a methodology which can be applied to identify best-practice policy instruments for specific districts by evaluating stakeholder’s acceptance of proposed policy instruments and the effects and impacts stakeholders expect for reducing carbon emissions and energy use in buildings in cities at the district level, combining both energy efficiency measures and renewable energy measures;
- Illustrate the development and assessment of innovative local policy instruments that could target the district level for achieving energy renovations and renewable energy systems;
- Provide the necessary background for recommendations to policymakers and their key partners on how they can influence the uptake of cost-effective combinations of energy efficiency measures and renewable energy measures in building renovation at the district level.@en

The present report provides guidance on the main concepts regarding building renovation and aims to set a common language for communication between local authorities, professionals, researchers, inhabitants and, in general, all the stakeholders and international partners. Each term is defined in the context and scope of IEA EBC Annex 75, namely building renovations at the district level, and combines definitions from the European legal framework, common definitions of English dictionaries, related projects, research papers, and other professional@en

The guidebook illustrates that the district, as an action level for building renovation, allows for synergies through combinations of energy efficiency measures and measures that promote the use of renewable energy and opportunities for stakeholders to cooperate, compared to an individual building approach. But building renovation at the district level also presents challenges. These include high upfront costs, a long payback time, and risks of not being implemented due to a potential withdrawal of some building owners at different stages. However, the studies also show that often the opportunities are greater than the challenges in district approaches, even if the cost-effectiveness of certain measures may not necessarily be one of these opportunities.
One main conclusion from IEA EBC Annex 75 is that assessments must be carried out for each district renovation project since no "ready-made" or "one size fits all" solutions exist. Still, several techno-economic potentials for district solutions are apparent. Furthermore, the research indicates that the best renovation solutions for a district-level renovation depend on the district's starting situation. The building insulation level, the installed heating/cooling systems, the availability of renewable energy sources and the possibility of integrating renewable energy are determining factors.@en

The present report aims to identify the key characteristics of business models important for upscaling business from the building to the district level. Understanding those characteristics and gaining insights about the opportunities the BMs offer for the different stakeholders will support the implementation of the renovation and the stakeholder dialogue. The methods implemented in the study included desk research and quantitative analysis of semi-structured interviews.@en

Among environmental controls, solar shading and ventilative cooling are widely considered as key passive strategies for limiting the overheating risks in buildings. While their application is encouraged through Energy Performance of Buildings Directive regulations, several studies have shown that summer thermal comfort in heating-dominate temperate climates still requires deeper investigation, particularly in low-energy residential buildings. Based on qualitative and quantitative data collected through surveys and monitoring in 147 highly insulated houses in Wallonia (Belgium), this paper gives an overview of the implemented passive strategies and discusses their effectiveness. Statistical tests are conducted to evaluate their impact on both perceived and measured indoor conditions. In general, the results highlight a limited impact of the implemented strategies, questioning their proper operation. Operational modes for environmental controls thus appear crucial, and should better respond to occupants’ needs, preferences and control opportunities. At a more general level, the study calls for a better understanding of the barriers inhibiting successful integration and operation of environmental controls, in order to effectively reduce overheating risks in residential buildings and limit future diffusion of active cooling systems with their induced environmental impacts.

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Energy efficient renovation (EER) of the owner-occupied building stock is identified as a key effort to pursue in order to mitigate climate change. However, current renovation rates continuously fall behind and a need to foster EER uptake is apparent. As homeowners' behaviour and decision-making are crucial in the context of EER, behavioural research holds vast potential for policy design and ultimately increasing EER uptake. So-called ‘spilling effects’ in the domain of pro-environmental behaviour (PEB) continuously catch the attention of researchers. Therefore, this article proposes a conceptual framework of ‘spilling effects’ in the context of homeowner EERs based on an integrative literature study, facilitating policy design.@en

De VvE-versnellingsagenda wil de verduurzaming van Verenigingen van Eigenaars (VvE’s) stimuleren door besluitvorming aan te passen, het renovatietraject te vereenvoudigen en financiële ondersteuning te bieden aan VvE’s. Het LIFE-project CondoReno omarmt deze visie en streeft bovendien naar meer renovaties en betere energieprestaties. CondoReno ondersteunt verschillende stakeholders voor de ontwikkeling van geïntegreerde woningrenovatiediensten (GWRD) voor VvE’s. Het realiseren van een betere samenwerking tussen de publieke sector en de vraag- en aanbodzijde vormt een belangrijke sleutel voor dit project. Met het voorliggend rapport ondersteunt CondoReno alvast de identificatie en classificatie van lokale en nationale stakeholders die een belang kunnen hebben bij de ontwikkeling van GWRD voor VvE’s in Nederland. Deze stakeholders hebben ook een belang bij het gebruik van toekomstige deliverables en tools, zoals archetypes van mogelijke bedrijfsmodellen, instrumenten voor dienstverleners, beleidsaanbevelingen en eisen voor fondsen, de realisatie van demonstratieprojecten en matchmaking tussen vraag en aanbod. De CondoReno-partners hebben het stakeholdersveld verkend d.m.v. bilaterale gesprekken en workshops. GWRD zijn momenteel vooral vertrouwd met het bedienen van individuele bewoners en kleine VvE’s. Voor de doorontwikkeling van GWRD voor VvE’s is een gevorderde samenwerking nodig tussen diverse stakeholders. Gemeenten spelen een belangrijke rol voor het faciliteren of aanbieden van aangepaste geïntegreerde diensten. Er is ook nood aan sociale deskundigen en procesbegeleiders die vertrouwd zijn met de VvE-besluitvormingsprocessen. Een woonlasten-optimale propositie vergt ook samenwerking met juridische en financiële adviseurs. Bovendien vergt het bereiken van gebouwprestatiegaranties ook de samenwerking met gespecialiseerde energiedeskundigen, master planners en kwaliteitsbewakers. Dit rapport geeft tevens een overzicht van de stakeholders die reeds hebben verklaard te willen werken aan de ontwikkeling van GWRD voor VvE’s in Nederland. Deze stakeholders werden gevraagd om deel te nemen aan een nationale CondoReno-adviesraad die adviseert over de nodige ontwikkeling van competenties voor - en samenwerking tussen – stakeholders. Gezamenlijk streven deze stakeholders naar het creëren van interesse, middelen en ontzorging voor VvE’s zodat alle VvE’s gebruik kunnen maken van geïntegreerde woningrenovatiediensten.@en

A comprehensive and detailed Guidebook (Meyer et al., 2023) was prepared to provide target group-oriented recommendations for policymakers and investors/decision-makers. As a supplement to this Guidebook, two complementary versions offer more straightforward guidelines oriented to each target audience, with a summary of the main recommendations. This document provides guidance for investors and decision-makers only.@en

This report aims to identify both barriers that hinder energy-efficient renovation of buildings and drivers enabling the implementation of energy and cost-effective renovation of buildings and energy supply systems at the district level. Fifteen success stories regarding barriers and drivers were analysed in the first step. These success stories consisted of projects from seven European countries (Austria, Denmark, Italy, Portugal, Spain, Sweden and Switzerland) where energy-efficient and/or renewable energy measures had been successfully implemented at the district level. In the next step, different stakeholders involved in energy renovations at the district level were interviewed about their experiences to identify barriers and drivers. In total, 39 in-depth interviews from eight countries (Austria, Belgium, Germany, Netherlands, Portugal, Spain, Sweden and Switzerland) were carried out. The stakeholders included policymakers, renovation solution suppliers, energy solution suppliers, clients and beneficiaries, financing intermediaries and other intermediaries. The barriers and drivers were divided into the following categories: policy, legal aspects, economic aspects, social aspects, communication, technical aspects, and knowledge and training.@en