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The purpose of this paper is to develop a knowledge elicitation strategy to elicit and compile home energy retrofit knowledge that can be incorporated into the development of an intelligent decision support system to help increase the uptake of home energy retrofits. Major problems accounting for low adoption rates despite well-established benefits are: lack of information or information in unsuitable and usable format for decision making by homeowners. Despite the important role of expert knowledge in developing such systems, its elicitation has been fraught with challenges.

Using extensive literature review and a Delphi-dominated data collection technique, the relevant knowledge of 19 industry experts, selected based on previously developed determinants of expert knowledge and suitable for decision making was elicited and compiled. Boolean logic was used to model and represent such knowledge for use as an intelligent decision support system.

A combination of comprehensive knowledge elicitor training, Delphi technique, semi-structured interview, and job shadowing is a good elicitation strategy. It encourages experts to describe their knowledge in a natural way, relate to specific problems, and reduces bias. Relevant and consensus-based expert knowledge can be incorporated into the development of an intelligent decision support system.

The consensus-based and relevant expert knowledge can assist homeowners with decision making and industry practitioners and academia with corroboration and enhancement of existing knowledge. The strategy contributes to solving the knowledge elicitation challenge.

No previous study regarding a knowledge elicitation strategy for developing an intelligent decision support system for the energy retrofit industry exists.

Vacation rental homes, in general, have different energy usage characteristics than traditional residential homes mainly because of the occupancy pattern that changes on a weekly basis. These homes, predominantly larger in size, offer a greater scope for energy savings also because of the wasteful habits of their seasonal occupants. The purpose of this paper is to investigate the causes of energy inefficiencies prevalent in these homes so that appropriate retrofit choices can be offered to homeowners.

This research presents a case study of a vacation rental home whose energy consumption was investigated in depth and energy inefficiencies identified through modeling using energy modeling software, eQUEST. Simulations were performed to identify viable retrofit scenarios.

While improvement in the building envelope such as providing shades/overhangs on the windows, reducing infiltration and increasing insulation of the exterior wall did not show promising results for savings on energy cost, other improvements such as use of highly efficient lamps, tank-less water heater system and occupancy sensors showed viable investment options with shorter payback periods. It was also found that energy use intensity of sampled houses was about half of the average of US residential buildings, which could primarily be attributed to the seasonal nature of occupancy of these houses.

There is a dearth of literature pertaining to energy efficiency-related retrofits of coastal vacation homes. This research fills that gap to some extent by addressing this issue with an ultimate aim of assisting homeowners in retrofit decision-making.

The purpose of this study is to investigate and analyse the potential of existing buildings in the UK to contribute to the net-zero emissions target. Specifically, it aims to address the significant emissions from building fabrics which pose a threat to achieving these targets if not properly addressed.

The study, based on a literature review and ten (10) case studies, explored five investigative approaches for evaluating building fabric: thermal imaging, in situ U-value testing, airtightness testing, energy assessment and condensation risk analysis. Cross-case analysis was used to evaluate both case studies using each approach. These methodologies were pivotal in assessing buildings’ existing condition and energy consumption and contributing to the UK’s net-zero ambitions.

Findings reveal that incorporating the earlier approaches into the building fabric showed great benefits. Significant temperature regulation issues were identified, energy consumption decreased by 15% after improvements, poor insulation and artistry quality affected the U-values of buildings. Implementing retrofits such as solar panels, air vents, insulation, heat recovery and air-sourced heat pumps significantly improved thermal performance while reducing energy consumption. Pulse technology proved effective in measuring airtightness, even in extremely airtight houses, and high airflow and moisture management were essential in preserving historic building fabric.

The research stresses the need to understand investigative approaches’ strengths, limitations and synergies for cost-effective energy performance strategies. It emphasizes the urgency of eliminating carbon dioxide (CO₂) and greenhouse gas emissions to combat global warming and meet the 1.5° C threshold.

This paper aims to discuss the nexus between two societal (sub) systems of housing and energy supply to shed new light on the key institutional barriers to socio-technical energy transition in the built environment. The key research question is to explore if and how key patterns of institutional elements associated with energy retrofit and energy supply are combined, co-evolved and played out in the housing system, leading to an alternative energy transition pathway in the built environment.

A comparative case study of residential buildings in the Swiss cities of Basel and Sion is conducted to map retrofitting policies and practices in a wide range of buildings (e.g. multi-family and single family) that each requires a particular constellation of institutions, actors and artefacts.

The key finding is that the regulative institutions support energy transition in each urban form/housing type. However, the co-evolution with normative and cultural-cognitive institutions does not play out very clearly in the housing system. One reason is that the norms and cultures are deeply rooted in the practices exercised by business community and households and therefore they need a longer time frame to adapt to a new regulation.

The policies and actions to increase the rate of housing retrofit are discussed in the specific socio-political context of Switzerland. Therefore, the results of this study might not be applied in other contexts with different conditions, limiting the possibility for analytical generalization. The case study can generate only context-specific knowledge, which might be valuable only to cities with similar conditions. This paper addresses theoretical, methodological and policy challenges in scaling-up retrofit projects by taking a holistic and integrated approach to the systems of housing and energy supply.

It would have been necessary to find out how the introduction and enforcement of new energy policies and regulations (regulative institutions) have changed the norms and building practices (normative institutions) used by actors from housing industry and the attitudes and energy consumption behaviour of the households (cultural-cognitive institutions). Nevertheless, information about normative and cultural-cognitive institutions require more primary data in the form of interviews with organizations and households, respectively, which goes beyond the scope and resources of this study.

Insights from different strands of literature (institutions and sustainability transition) are combined to understand if and how retrofitting practices go along with other elements of urban sustainability including architectural, technical, socio-cultural and economic factors.

Among the existing buildings, hotels use as much as 50% of their total expenses on energy and offer significant opportunities for energy efficiency improvement. Yet, comparatively the level of implementation of energy retrofits (ER) in hotels appear to be low. This has been mainly attributed, inter alia, to the absence of clearly defined process for ensuring the delivery of ER and lack of proactive guidance for project teams to make right decisions. Hence, this study aims to propose an effective decision-making process, which could support the successful adoption and implementation of in-house-led ER projects in existing hotel buildings.

Two in-depth case studies were carried out focussing on ER projects led by in-house teams in existing hotel buildings. Data was collected via 14 semi-structured interviews and was analysed through code-based content analysis.

The decision-making process for ER projects led by in-house teams was developed, which presents 39 key activities to be performed and 16 key decisions to be made. The parties responsible for these identified actions and decisions as well as the points at which each decision should be made to ensure the success of ER projects was also identified.

A total of 21 new activities and 10 decisions relevant for in-house team led ER decision-making processes previously not found in literature were identified. It is hoped that the decision-making process developed in this study will serve as a roadmap for the effective adoption and implementation of ER in existing hotel buildings.

This paper aims to propose a methodology for assessing an optimal portfolio of investment instruments that minimise the social costs of decarbonising economic activity while improving the environmental objectives proposed in EU legislation.

The methodology defines the net social cost of decarbonisation related to a portfolio of four instruments: installation of solar PV and wind generation, thermal insulation of households and deployment of heat pumps. The social cost is minimised by restricting it to the minimum level of the targets proposed in the Spanish National Energy and Climate Plan to reduce greenhouse gas emissions, increase generation from renewable sources and reduce energy consumption. The empirical approach also includes differences between regions according to the expected effect for instruments.

The application of this methodology to the environmental objectives defined in the current Spanish National Energy and Climate Plan for 2030 concludes that it is clearly possible to reduce the social cost of decarbonisation while improving environmental performance through a reorientation of investment instruments. In this case, such a reorientation would be based on a minimisation of efforts in thermal insulation of households and a maximisation of measures aimed at the installation of heat pumps.

The paper proposes a novel methodology for a social cost assessment that improves the allocation of a portfolio of environmental instruments. This portfolio could be extended in further work to include instruments related to transport or support for industrial decarbonisation, such as the deployment of renewable hydrogen, among others.

Despite their energy conservation potential, still existing buildings are slow in embracing building energy efficiency retrofits (BEER), mainly because of the absence of a clearly defined process to deliver the BEER projects, and the lack of proactive guidance for project teams. Further, the identification of factors that can facilitate BEER projects is also important to ensure the project success. This is particularly true in energy service company (ESCO)-led projects. Hence, this study aims at investigating the decision-making process, including the motivators for the successful execution of each stage in implementing BEER when projects are outsourced to a third party.

An in-depth case study was carried out to investigate the decision-making process and motivators in implementing BEER in a selected hotel building. Seven semi-structured interviews were conducted to collect the required data within the case.

Study disclosed the 13 key decisions made and 37 key activities performed in each stage of the project. A total of 19 motivators for the successful execution of the respective stages were also elicited. Ultimately, the research findings are mapped against the five key stages of BEER decision-making process.

The outcome of this study will provide the industry practitioners a basis for the effective adoption and implementation of BEER in existing hotel buildings when an external contractor is involved.

Existing buildings encompass the largest segment of the built environment and, hence, have become a key target for energy retrofits (ER) to substantially reduce global energy usage. The success of ER projects is closely linked to the effective involvement of various stakeholders within the decision-making process. This paper aims to investigate different stakeholders and their involvement throughout the decision-making process of ER projects.

Two successfully implemented ER projects in existing hotel buildings were selected as cases to gain novel insights into the key stakeholders to be involved along with their functions and roles in five different stages of the ER decision-making process. To collect required data, in total 11 semi-structured interviews were conducted with stakeholders involved in different stages of the decision-making process in the respective case studies. Data was analysed using code-based content analysis with the aid of NVivo computer software.

Altogether, 18 stakeholders and 7 roles reflective of the nature of their involvement in the respective stages were established. Findings disclosed that the nature of the project, level of knowledge, expertise and commitment of internal staff, type of ownership of the facility and mode of financing have significant influence on involvement of different stakeholders in ER projects.

The findings of this study are useful in enhancing the successful adoption and implementation of ER through timely and effective involvement and integration of stakeholders.

Office buildings confront with the issue of high energy demand during the day time mainly due to heavy use of energy for HVAC and lighting systems. Demand-side energy retrofits (DSER) are identified as effective in controlling electricity demand of existing buildings. The purpose of this paper is to analyse the potential of incorporating DSER in to existing office buildings. The paper reports the cost benefits of using DSER in existing office buildings. Furthermore, it reveals several enablers that can be used to promote retrofits in office buildings of Sri Lanka.

An industry survey was conducted by selecting a sample of 35 office buildings to study the usage of DSER in office buildings of Sri Lanka. Furthermore, three case studies were conducted to analyse the costs benefits of widely used DSER techniques in office buildings.

Research revealed that the use of DSER techniques in existing office buildings of Sri Lanka is at a lower level. However, it found that the financial viability of those DSER was at a promising level. Furthermore, 11 enablers in two levels as organisational level and national level were identified to enhance the use of DSER.

The study justifies the potential of DSER in reducing energy demand of existing office buildings through in-depth cost benefit analysis, which is useful for a country like Sri Lanka which faces massive energy crisis. This encourages Facility Managers towards using DSER to reduce building energy demand. Furthermore, study provides enablers at organisational and national levels to enhance the use of DSER.

The success of energy retrofits (ER) projects is highly dependent on the involvement of right stakeholders at the right stage. So far, little insight is available from previous literature on the involvement of different stakeholders during various stages of the ER decision-making process, and their roles and functions in the respective stages. This is specifically true in the context of Energy Service Company (ESCO) led ER projects, which is an emerging trend in the current context. Hence, this paper aims to investigate the roles and functions of stakeholders during different stages of an ESCO-led ER project in the hotel sector.

An in-depth case study was conducted in a selected hotel building to gain insights into the roles and functions of stakeholders throughout the project stages. To collect the required data, face-to-face semi-structured interviews were conducted with seven selected respondents within the case.

The study identified nine key stakeholders that were involved during five different project stages along with their functions. Based on these identified functions, four main roles (i.e. decision-maker, performer, monitor/observer, and supporter) emerged that were reflective of the nature of the stakeholders' involvement in different stages of the decision-making process. Owner/client, facilities manager (FM), ESCO and architect attached to ESCO emerged as the key “decision-makers” during project implementation process.

The outcomes of this research would be useful in ensuring the proactive involvement of all the identified stakeholders in respective project stages of ESCO led ER projects in the hotel sector.