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Local authorities (LAs) play an essential role in diffusing home energy renovation measures. However, there are rare business models developed for local authority actions. This paper aims to develop a critical review of the way that local authorities developed business models for pop-up centres where consultants can encourage home energy renovation measures. From 2017 to 2021, participatory research was conducted in collaboration with seven LAs from the UK, France, Belgium, and the Netherlands. Although local authorities could use business model approaches for the development of pop-up home renovation consultancy centres, we noticed that LAs could not apply specific strategies to fit various customer segment groups. Therefore, a traditional business model needs to be investigated further for local authority activities.

Many multi-owned condominiums need an energy renovation, but in practice the number of such renovations is low. Dutch policy emphasizes the need to search for cost-neutral renovation solutions. This study therefore examined how the number of living-cost neutral renovations of buildings owned by assemblies of homeowners in the Netherlands can be increased by means of an integrated unburdening offer that includes energy performance guarantees and supply chain integration. The study uses scientific literature, project experiences and in-depth interviews with experts to examine how policy, demand and supply currently play a role in the upscaling of living-cost neutral renovations. The study finds that customized guidance is needed for condominium associations to steer their maintenance decision processes towards deep renovations. Also chances are detected to link living cost neutrality with energy neutrality, while developing an integrated supply chain that takes into account full process guidance including the provision of performance guarantees. This is now already successfully implemented in a new non-profit service desk and a new process model will be tested in multiple regions.

Web portals have the potential to promote sustainable environmental ideas due to the capacity of digital media, such as easy accessibility, openness, and networking. Local authorities (LAs) are responsible for activating carbon savings in homes, and they are key actors when it comes to providing neutral information to their citizens. Local authority web portals may thus create environmental awareness, particularly regarding owner-occupied single-family home renovation. Nevertheless, the experiences of LAs developing web portals have rarely been studied. Therefore, this paper analyses the development process of various LA web modules and investigates how LAs foster modular web portals to stimulate the adoption of home renovation with parameters to assess LAs’ actions in terms of the management of web-modules development. A homeowner renovation journey model is applied to map current local authority developments. Case study research and interviews were done to analyse and evaluate the adoption of modular web portals developed and tested by six local authorities in four countries in Europe. Based on the development and use of the modular web portal, lessons have been derived emphasising the importance of co-creation, integrating with offline activities, and a strategic management plan.

© 2019 Published by Elsevier Ltd. European energy policies call for an increased share of renewable energy sources and a more active role of the energy consumer. This is facilitated by, amongst others, buildings becoming energy flexible hubs, supporting smart energy grids with demand response strategies. While there is abundant technical research in this field, the related business and policy development is less well documented. This research scopes existing policy programmes and identifies opportunities and barriers to business devel-opment supporting energy flexible buildings. Using examples from seven European countries, this work reviews influencing niche management factors such as existing policy instruments, business development cases and identified stakeholder concerns, using literature research, narrative analysis and stakeholder research. National policy pathways show many differences but confirm that European buildings might become active players in the energy market, by providing energy storage, demand response and/or shifts in the use of energy sources. Slow sustained business development for energy flexibility services was mainly identified in the retail industry, and for energy service companies and aggregators. The direct involvement of end users in energy flexible buildings is still difficult. Stakeholders call for policy improvement, especially concerning the devel-opment of flexible energy tariffs, supporting incentives, awareness raising and more stakeholder-targeted busi-ness development. This research was done in the framework of the IEA EBC Annex 67 Energy Flexible Buildings. The authors would like to thank the operating agent and members for their engagement. National contributions were supported by national participants who would like to thank their funding agencies. The Dutch participation to the IEA EBC Annex 67 was supported by the Dutch Enterprise Agency (RVO). The Spanish contribution was supported by the GEIDI Project (ref. TIN2016-78473-C3-3-R) financed by the Ministry of Economy and Competitiveness of Spain. Peer Reviewed Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant

Renovation at district scale is a key strategy to reduce CO2 emissions by optimising the implementation of renewable energy sources and taking advantage of economy of scale. This paper focuses on analysing good practice examples on energy renovations at district scale. The paper adapts a qualitative research methodology in four phases, including the multi-perspective analysis of nine exemplary renovation projects in six European countries, including identification of drivers and barriers of different stakeholders. It is found that the drivers for a district renovation are not restricted to energy savings, but typically also include improving the overall quality of life as well as the image and economic value of a district. Moreover, the need for financial models that can alleviate split-incentive problems between investors and resident organizations is identified. Barriers for carrying out a district renovation include that there is a need to comply with energy standards, that the renovation scope had to be limited to avoid a noticeable rent increase and that resettling of tenants during the renovation is often not possible. Lessons learned include that good communication amongst the different stakeholders, especially with residents, plays a key role for the success of the project. Furthermore, a strong leadership is needed to coordinate activities due to the great number of stakeholders.

In a context of global warming, summer thermal comfort is a key issue for the design and operation of nearly zero-energy buildings (nZEBs). Although there are various methods and benchmarks for the long-term evaluation of summer thermal conditions in free-running buildings, their application to the residential sector is still debated. Based on data from post-occupancy measurements and survey campaigns, this paper evaluates the compliance with commonly used overheating criteria defined by existing standards (CIBSE and Passive House Institute) of 23 nZEB houses in Wallonia (Belgium). The quantitative relationship between measured and perceived comfort is statistically analysed, and building characteristics leading to the most critical overheating situations are qualitatively discussed. The results show that summer thermal discomfort is frequent in nZEB houses in Wallonia, despite its temperate climate. In living rooms, the long-term appraisal of thermal conditions appears to be related to the frequency of extreme temperatures, while occupants’ thermal perception in bedrooms seems to be more affected by smaller temperature deviations. These results imply a critical review of the capacity of the criteria commonly used for the evaluation of overheating risks in free-running residential buildings to predict the satisfaction of occupants with their summer thermal comfort. More generally, the findings reinforce the importance of a better integration, even in temperate climates, of environmental controls – and their required operation by the occupants – to properly mitigate overheating risks in nZEB houses.

In the EU, housing retrofit rates have to increase to about 2.5–3% of the housing stock per year to achieve policy goals. The development of new business models and collaboration of SMEs in a fragmented market is expected to result in an increase in home renovations. This study presents a way to better understand the usefulness of the business model as a market device for collaborating firms for realising home energy renovations, by analysing literature and action research observations. Joint innovation decisions during business model development were traced back for 24 groups emerging from the supply side in five European countries. Commonalities for all groups were analysed to understand the usefulness of the business model. The business model development experiences show that effort is still required to support SME collaboration and to introduce basic marketing knowledge within SMEs, particularly to identify the customer segment and its values and to clarify the effectiveness of existing communication channels. Business models appear to be very useful for collaborative vision formation and networking and for clarifying the need of customer-oriented approaches that include project management and structured guidance of homeowners. However, they do not readily lead to the introduction of collaborative businesses, for which action plan are needed. Collaborating companies are advised to pay specific attention to identifying quality assurance and independent advice for home energy renovations. The research acknowledges the success of action-based research approaches to support collaborative business development and recommends its future use to speed up market development.

The housing sector is responsible for a more than a quarter of the total final energy consumption in the EU. As the majority (70%) of the EU-housing stock is owner occupied and largely consists of single family dwellings it is understandable that many countries focus their energy saving policies on homeowners. Complementary to the national policy frameworks, regional and local authorities implement locally based policy instruments targeting specific groups and individual homeowners. In order to enlarge the effectiveness of their policy instruments and to reach the energy saving goals, frontrunner local authorities in particular are searching for ways to reach homeowners. Consultancy centres and pop-ups can be a way to make individual homeowners more aware about their energy use and stimulate them to apply low carbon technologies. The research results not only show that a wide range of business models are available to develop, structure and organise these consultation centres and pop-ups, but also that they indeed could play an important role in accelerating the energy performance of owner occupied housing. Through a pop-up or consultancy centre, public and private parties can join their forces to reach, stimulate and support the individual needs and wishes of homeowners during their customer journey to realise an energy efficient dwelling.

In-depth knowledge from demonstrations is needed for the future development of facility management, related to the introduction of energy-saving devices, buildings and energy systems. Particularly there is a need to understand better how the concept of Energy Flexibility can effect energy saving strategies and innovation decisions. Using a district heating network installation as a case study (TU Delft university campus in the Nether-lands), this research investigates the opportunities and barriers that stakeholders en-counter.To save energy and to deploy renewable energy systems, the Technical University of Delft is looking for ways to lower the heat supply temperature in the local (heat) grid on its campus. This implies that the connected individual buildings on the campus will need to be able to manage their energy demand more effectively, taking into account the new grid requirements, as well as the local climate conditions and user needs for indoor comfort, while delivered network supply temperatures for heating are lowered.This innovation adoption study first analyses the motivations of stakeholders to change grid requirements at the TU Delft campus and the opportunities and barriers they encounter for introducing energy flexibility in the campus buildings, due to these changing grid requirements. The transition from a high to a medium supply temperature has far-reaching consequences on the facility management of the buildings and the redevelop-ment of the heat grid.Secondly, this study looks at the main results from comfort simulations and real-life experi-ments to transform the heating network with a smart control system, with the aim to provide relevant information on encountered opportunities and barriers regarding facili-ty management.Thirdly, the study discusses the encountered portfolio management opportunities and barriers from the viewpoint of innovation adoption.The research concludes that the introduction of a smart heat network can be successfully test-ed on an estate of buildings with one estate operator. The smart control system can lower the heat network supply temperature in an individual heat network branch, which can support the implementation of renewable energy systems. However, this requires a time shift in the energy use of individual buildings and technical modifications of hardware, devices, buildings and systems.The visibility of energy flexibility still needs to be improved and research results show an urgency to lower complexity for facility management. The lack of interoperability of building management, control and data transfer systems is an important practical barri-er for facility management. Limited suitable business models, the lack of framing of energy flexibility for sustainable portfolio management, and legal barriers can further hinder adoption of energy flexibility.

The house construction sector in Europe is facing the need to meet stricter energy requirements. For example, some customers are demanding passive houses with almost no demand for space heating. Passive house quality assurance systems have been introduced to certify the energy performance of such houses. The aim of this study was to identify opportunities for improving passive house certification in line with customer's comfort expectations. Questionnaires, site visits and interviews were carried out to identify and assess the comfort concerns of owner-occupiers in certified single-family passive houses in Flanders, northern Belgium. The results show that certified passive houses in Flanders are well rated and perceived as very comfortable. However, there were some cases where comfort concerns were expressed related to perceived flaws in the design or construction of the building services. In particular, the study recommends incorporating criteria for the planning and installation of user-friendly ventila...

The construction of highly energy-efficient buildings is more than an emerging business opportunity, it is also a major challenge in systemic innovation, particularly for SMEs, which are more accustomed to incremental innovation. Accordingly, this study searches for new innovation opportunities for supplier-led innovation in highly energy-efficient housing by examining the innovation journey and analysing the innovation opportunities and barriers encountered by a successful innovator in Flanders. Existing innovation models and innovation barriers and opportunities in the construction of highly energy-efficient housing are discussed within the framework of the theory on systemic innovation. The successful innovation journey of a supplier illustrates how coordinated collaboration can help an incremental (technological) innovation idea to develop into modular, system and even radical innovation. The study highlighted the importance of suppliers as players in the development of innovation. To successfully introduce innovation (even incremental innovation) suppliers need to join forces with other organisations and respond to the challenges of systemic innovation. Demonstration projects and collaboration between SMEs are key to achieving the modular and architectural innovation needed for highly energy-efficient housing. Given the specificity of both the construction sector and highly energy-efficient housing, the supplier should be given explicit guidance on how to link modular innovation to architectural and system innovation. Finally, the study also showed that players in dedicated radical innovations such as passive house networks can contribute to the market uptake of innovation.

High end-user satisfaction levels are key for the acceptance of nearly zero-energy housing. Post-occupancy evaluation research on highly energy-efficient dwellings can lead to recommendations which will influence their performance in the expected future large volume market of such houses. This study analysed mainly German, Austrian and Swiss post-occupancy evaluation research results on nearly zero-energy dwellings and undertook a survey of occupants of nearly zero-energy houses in the Netherlands. The study determined how various comfort parameters (such as winter thermal comfort, summer thermal comfort, indoor air quality and acoustics), information provision and control parameters are related to positive or negative end-user appraisal, finding that summer comfort design and the quality of – and information about – heating and ventilation systems are critical factors which must be addressed to improve user satisfaction in nearly zero-energy dwellings.

In theory, there is huge potential for reducing the energy consumed by existing single-family houses by thoroughly renovating them. For the successful market development of highly energy-efficient integrated renovations, supply chain collaboration is very important, while at the same time customer demand for integrated renovations has to be stimulated. A research and networking methodology was developed within the framework of the One Stop Shop project to identify and develop collaboration opportunities for advanced housing renovation in Belgium, Denmark, Finland and Norway. The research identified key supply-side needs through interviews and questionnaires, and analysed important elements for the development of a web-based portal that can connect supply and demand. The project further developed ideas and methods for collaboration and business model generation between different players on the renovation market. These different research results contributed to defining new business opportunities related to process innovation to unburden the homeowner and to achieve less fragmented renovation processes.

Promoting energy efficiency in the building sector is essential if the agreements of the Kyoto Protocol are to be honoured. Different initiatives for energy labelling of highly energy-efficient residential buildings have emerged throughout Europe as an essential method to stimulate market demand, to control grants or to ensure the quality of demonstration projects with excellent energy performance. The paper identifies the barriers and opportunities for the further diffusion of labels for highly energy-efficient houses. A model based on the theory of the diffusion of innovation is developed to analyse perceived attributes of existing European labels. The paper investigates the innovation characteristics of existing labels in Europe, with a focus on advanced countries. The question of compatibility with the development of the European Energy Performance of Buildings Directive (EPBD) is examined in detail. We found that the diffusion of emerging and already existing voluntary European labels for highly energy-efficient houses is needed. Their complexity can be lowered and relative advantage, trialability, observability, and compatibility can be increased. EPBD calculation procedures should be able to receive highly energy-efficient houses. In the framework of the recast of the EPBD, official recognition of existing voluntary labels is recommended.

Vanaf eind 2020 moeten alle nieuwe gebouwen in Nederland bijna energieneutrale gebouwen (BENG) zijn, conform het Europese Directief voor Energieprestaties van Gebouwen (EPBD). Voor woningen en woongebouwen in Nederland [1] betekent dit dat de energiebehoefte voor verwarming+koeling en het primair energiegebruik dienen te worden beperkt tot 25 kWh/m2.jr, grosso modo vergelijkbaar met een EPC van 0,2. Het percentage duurzame energieopwekking dient bovendien minimum 50% te bedragen. Iedereen is enthousiast over de Big BENG, maar levert de markt wel dat wat de bewoners waarderen? Wat leren we van meer dan vijf jaar onderzoek naar bewonerservaringen aan de TU Delft? BENG hebben nood aan een zorgzamer ontwerp, een waakzamere uitvoering en een verregaande samenwerking tussen bedrijven. Gebruiksevaluaties kunnen slim worden ingezet om comfortproblemen te detecteren. Bewoners van BENG moeten echter ook bijkomende informatie krijgen en de renovatiemarkt vraagt een extra stimulans.

The supply side for nearly zero energy building (nZEB) renovation of owner-occupied single-family houses in Europe is suffering from a severe image problem of lack of knowledge and trust, inefficient construction processes, insufficient quality assurance and communication difficulties with home-owners. Research was done in Austria, Belgium, Germany, the Netherlands and Norway as part of an Intelligent Energy Europe project, entitled “COHERENO - Collaboration for housing nearly zero-energy renovation” to understand the emergence of collaboration structures for nearly zero energy building (nZEB) renovation of owner-occupied single-family houses. The business model of Osterwalder and Pigneur (2010) is used as a reference of the project. Used research methodologies include desk research, explorative semi-structured interviews and focus groups. Based on this, barriers and opportunities for collaboration and business model development in this market segment were detected. Important barriers on the supply side are a lack of knowledge, particularly understanding the necessity for and approaches of collaboration, and to address customer values. Also, there is a lack of capacity to absorb knowledge in small enterprises. On the demand side, there is a lack of confidence in professionals’ experience. Home-owners expect independent advice and tailored pricing. Some of the home-owners expect one actor to take the lead and be the ‘reassuring’ contact point. The way how to collaborate was addressed in the second part of the COHERENO project by organising Business Collaboration Events and action research on business modelling of cooperation structures in the different countries.

It is poorly understood what the characteristics are of households who want to engage in nZEB single-family home renovations. This paper addresses the research question: What are customer segments, and what are their customer values and motives to choose for a nZEB renovation of privately-owned single-family dwellings in the Netherlands? Research methods are a literature review, a home-owners questionnaire and home-owners interviews. In the Netherlands customer segmentation for nZEB renovations currently is not useful because of the limited actual size of the market. One could focus on somewhat older households, high educated and with an income which is on average or above. Characteristics of the dwelling, the energy use, the technical status and inherent comfort levels could be taken as main ingredients for value propositions. Trust in professional involved actors and objective advise are very important issues in customer relationships.

This report is part of an Intelligent Energy Europe project, entitled “COHERENO - Collaboration for housing nearly zero-energy renovation” (www.cohereno.eu). The main objective of this project is to strengthen the collaboration of enterprises in innovative business schemes to develop nearly Zero Energy Building (nZEB) renovation in owner occupied single-family homes.

The mixing of different polyolefins, several calcium-based fillers, and a type of vegetable oil was investigated. The effect of viscosity and type of polyolefin on Young's modulus, yield stress, and elongation at yield has been determined. Tensile and machine torque properties have been studied for both mixing at 180°C and at 250°C as a function of the content of several types of calcium carbonate or calcium hydroxide filler. The influence of the addition of a sunflower oil as a lubricant has also been characterized. SEM micrographs indicate some problems of the formation of agglomerates and the influence of particle size on matrix morphology and filler/matrix adhesion. Physical and chemical interactions among high-density polyethylene (HDPE), vegetable oil, and calcium hydroxide was noticed. Spectra from infrared spectroscopy illustrate the formation of structures similar to metallic soaps, which integrate well within HDPE. Compared to calcium carbonate, results reveal excellent possibilities for the use of calcium hydroxide as a filler for polyolefins. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2761–2772, 1997

Europe expects the housing sector to evolve towards ‘nearly zero-energy’ dwellings. Meanwhile, general terms and research, marketing and legal definitions considering such dwellings have already been introduced. Appraisal of existing definitions is now needed for further policy development. This paper examines what nearly zero-energy terms can be expected to be adopted in Belgium and the Netherlands. The research method uses an interview method based on innovation diffusion theory. The analysis traces the regional adoption trajectory of relevant definitions and examines the opportunities and barriers for the inclusion of existing definitions in regional energy policy. The analysis shows that—whilst international prominence of the terms ‘net zero energy’ and ‘net zero carbon’, in addition to ‘low energy’ and ‘passive house’, is observed—in Belgium and the Netherlands ‘passive house’ and ‘energy neutral’ are preferred. The research findings indicate that the adoption of already existing definitions for nearly zero-energy houses will depend on the region and can prove a very complex process with several conflicting issues. Terms should be clearly defined and used at all political and marketing levels. It is recommended to enhance the relative advantage, demonstrability, visibility and compatibility of favoured definitions by policy initiatives

From the previous LEHR-project, it became clear that many retrofit projects are executed in a very fragmented way: many actors do a certain part of the works, without cooperation or coordination. Sometimes, there is a lack of attention for works that have been executed already, or the works that have to be executed afterwards are not kept in mind. This is however very important, especially when striving for nearly zero energy buildings in housing. It is desirable that every activity executed in a renovation, is integrated in a global concept, and thus takes into account the works executed earlier and afterwards in the process chain. The presented research was executed during the One-Stop-Shop-project. It maps these interactions for thorough, nearly-zero-energy, retrofit projects, using a structured approach (matrix), a process analysis and contacts with frontrunners in the field. An overview is given of the most important and critical attention points during design and execution, when different actors intervene in the same project. This overview allows for the development of solutions. These can be a more integrated execution of the works and/or the application of innovative technology. A selection of solutions is presented.

This study examines opportunities for the emergence of SME networks regarding highly energy-efficient housing, as well as the barriers they face. A theoretical innovation diffusion model is developed from the point-of-view of social and environmental entrepreneurship and sustainable consumption. The qualitative analysis reflects key elements from the theoretical model and is based on a representative case study of a successful passive house network located in the Belgian Flemish Region. Data were gathered during the emergence of the network, by means of participant observation and action-based (thematic innovation) research. Interviews provided further supplementary information. The study concludes that the successful emergence of an SME network regarding highly energy-efficient housing requires a holistic approach, in which both enterprises and clients are guided in each step of the innovation-decision process. In their role as intermediaries between clients and firms, change agents should be supported by policy that facilitates networks for innovation diffusion.

Europe now expects an evolution of the building sector towards „near zero energy? buildings. In Belgium, the passive house concept offers a feasible portal towards 0-energy developments. Meanwhile, for the major market of renovations, we still have to learn-by-doing what is achievable from demonstration projects. Different technological options and concepts (low energy, passive house, zero energy) to reduce the energy consumption have been analyzed in the framework of the Belgian Low Energy Housing Retrofit (LEHR) project. Based on the LEHR research, the paper discusses the Belgian context for 0-energy development, and the feasibility of achieving 0-energy renovations by means of the passive house concept in Belgium. We present a detailed case study and discuss results and lessons considering innovation adoption. The research detected possibilities and hindrances considering the market introduction and early adoption in Belgium of innovative technologies and concepts for reaching near zero energy renovations in Belgium.

This paper examines if and how indoor climate systems are important for passive house certification. The research subjects are passive houses in Belgium, occupied by owner-clients. These have received a quality assurance certificate from an independent organization. Through interviews with the owners, and on-site analysis of indoor climate installations in passive houses, the selection of indoor climate systems for passive houses was analyzed and insights were obtained in changes occurring after certification. Also, two houses were analyzed during further visits, including interviews and measurements, to allow detailed performance evaluation of the indoor climate systems. The paper concludes that adaptation of certification procedures is recommended, by looking more closely at the practical implementation of indoor climate systems. The paper further questions the general validity of the scientific basis of the passive house definition.

For the realization of the first passive house demonstration projects in Belgium, passive houses were requested by convinced clients, designed by architects with experience in low energy building, and built by contractors with a feeling for working in building teams. These first passive house examples were not limited to one specific building system, but already showed a diversity in technical solutions. Due to networking initiatives and financial stimuli, the demand for passive houses has grown exponentially in Belgium, like in other European countries. Nowadays, clients base their decisions on available grants and tax reductions, any architect is consulted for building a passive house and many contractors still lack experience and practical information. The Presti 5 research project ‘Details in the passive house standard’ acknowledged this lack of practical information. Its goal is to multiply the realization of good construction solutions to assure the quality of construction of further passive houses. This is done by defining and spreading practical design outcomes for the Belgian building situation, providing both design and construction information. In collaboration with the building industry and knowledge institutes, building details are designed and established for both massive and wood construction of passive houses, linking the innovative construction techniques of a passive house to the Belgian building tradition. Working groups were formed that discussed these details on a regular basis. Thus, in the scope of less than one year more than 10 fundamental building details have been finalized, in agreement with building industry and knowledge institutes. This paper gives an overview of the existing innovative solutions in Belgian passive house construction, discusses experiences and the potential of the related research process, and discusses examples of construction details in passive house standard, with specific concern for the thermal quality and air tightness. The building details will shortly be spread to all Flemish architects in order to multiply the local knowledge on passive house construction. It is recognized that with the current state of the building market, good building details are essential for the broad introduction of passive houses. Finally further research ideas are discussed.

Following the good examp les of new buildin gs and renovations with outstanding ener gy p erformance, a main challen ge is to brin g holistic sustainable construction concep ts for new and existin g buildin gs into mass mark et. It is still at an early stage in mark et develop ment and lessons between residential or non -residential build in gs can be exchan ged. To better understand the develop ment of the mark et of high ly ener gy -efficient construction, several International Ener gy A gency (IEA) Tasks examined op p ortunities and barriers of mark et develop ment. This p ap er summarizes main barr iers and drivers detected in the differ ent tasks, involving worldwide insights from research ers and develop ers. Finally it is discussed how segments interact on each other, and how authorities may influence.

According to the definition, passive houses in Europe meet a target energy demand for heating of less than 15 kWh per square meter and per year. This low level for the heating demand is based on heating by a small post-heater in the hygienic ventilation system at 52 °C maximum, while the ventilation system can be dimensioned purely for ventilation purposes. In theory thus the installed heating power is less than approximately 10 Watts/m2. But what happens in practice in renovations? Example projects of low energy housing retrofits and their indoor climate systems in winter and in summer were examined. The study includes inspection of technical details and interviews with occupants of some renovation projects. It is shown that the practical realization of very low energy houses can be different from the original passive house definition, but also that the passive house standard is feasible in difficult conditions. The results illustrate the concerns of occupants considering winter and summer comfort and health, and the difficulties of choosing adequate ventilation and backup heating when the passive house standard is not reached. Also, a good realization of (passive) cooling and solar shading is a very important issue. The research further illustrates tendencies in innovation considering design of ventilation systems for renovation purposes, including possibilities of space reduction, prefabrication, decentral heat recovery and improved user friendliness of indoor climate systems for passive houses.

For newly built houses and renovations European and national ambitions prescribe increasing levels of energy performances, even including achieving the passive house standard, net zero energy or carbon neutral houses. For highly energy-efficient renovation, project information from first demonstration projects is now becoming available. This paper examines experiences of demonstration projects with improved energy performance, in order to diffuse these experiences to reach other innovators and the early adopter market. Innovation diffusion theory is used to analyse examples of residential renovations using passive house technologies. Further the paper examines challenges and opportunities for the diffusion of demonstrated solutions to an early adopter market. Detailed case studies show that passive house retrofit, as well as low energy retrofit, need more holistic approaches, higher skill competence and strong process coordination. The results show that it is technically feasible to reach outstanding energy performance in renovation. However, social, political and economical issues remain important barriers to reach a more substantial market share. In particular there is a need to cluster energy efficiency principles to focus on substantial energy savings. The research leads to ideas for further study of the possible role of change agencies to support substantial energy reduction in retrofit projects.

Buildings account for 40% of EU final energy demand and policy developments like the Energy Performance of Buildings Directive are stimulating the innovation development for nearly zero-energy housing. However, businesses switching to innovative products for highly energy-efficient houses is a process that is poorly understood. To accelerate nearly zero-energy housing, all obstacles that currently restrict the distribution of innovation - experienced by end users, businesses and policy makers - must be defined and tackled simultaneously. These barriers and opportunities have been described in detail in a market study, three business innovation studies, three studies on end user experiences and three policy studies. These studies were recently assembled in a book. The enterprise studies confirm that collaboration between companies is essential to innovation, even beyond the usual ad-hoc knowledge application and the individual collaboration during demonstration projects. One major obstacle is the transfer of the necessary technical knowledge and skills by the few pioneers to the other companies. Manufacturers, in particular, play a key role in the adoption of innovation and the transfer of new insights to small and medium-sized enterprises, which are a key target group for the market introduction of new concepts in the building sector. Only a small group of occupants is interested in the energy savings and new forms of sustainable living. The study shows that end users can be motivated by low energy costs and improved living quality. They may be adequately satisfied with their homes, particularly with the high level of comfort. The policy studies confirm that the government should play a more active part in getting energy-efficient housing off the ground, especially house renovations: the business community should be encouraged to develop more innovations which requires financial resources. Manufacturers and suppliers switching to innovative products for ultra energy-efficient homes is not a standalone process of companies promoting technologies which consumers then use. Innovation is a diffuse process which must be approached from a policy perspective as well as the demand and supply perspectives.

More significant reductions in residential primary energy consumption and in space heating in particular, can contribute to achieving climate change and energy efficiency objectives. Project information from demonstration projects is now becoming available for highly energy-efficient renovation concepts. The goal of this research is to understand how owner-occupants can be persuaded to apply far-reaching energy-saving renovations of single-family houses. To this end, the research examines drivers and barriers of owners to adopt highly energy-efficient renovation concepts. Theory on decision processes in innovation diffusion is used, in order to examine the adoption of integrated concepts to achieve high energy performance. Belgian case studies (different building typologies) were examined. Adoption drivers and barriers perceived by owner-occupants are analysed. This leads to improved understanding of characteristics that can persuade future adopters. Possible measures are discussed to overcome barriers in the introduction phase of innovation diffusion, and are illustrated more in detail with a case study. The research shows that especially expectations of improved comfort provide an opportunity for the market entry of integrated concepts. Owners, architects and contractors could benefit from increased attractiveness, competitiveness, affordability and availability of highly energy-efficient renovations. Holistic approaches (stronger coordination and clustered renovation concepts), higher skill competence (education) and improved communication (actor networks, significant economic incentives) are recommended.

It is expected that future buildings will be able to manage their demand and generation not only according to local climate conditions and user needs, but also related to changing grid requirements. This development will introduce new challenges regarding asset management, which so far have not been explored. This innovation adoption research identifies key opportunities and barriers for asset managers from a case study that considers changing grid conditions on a university campus in the Netherlands. The case illustrates that implementing energy flexibility is certainly not only a problem of data communication and transfer. The paper sets the scene that asset management for energy flexibility also requires detailed consideration and planning of required technical changes in buildings and grids.

This report is part of an Intelligent Energy Europe project, entitled “COHERENO - Collaboration for housing nearly zero-energy renovation” (www.cohereno.eu). The main objective of this project is to strengthen the collaboration of enterprises in innovative business schemes to develop nearly Zero Energy Building (nZEB) renovation in owner occupied single-family homes.