The UK has one of the least energy-efficient housing stocks in Europe. By 2030, the emissions from UK homes need to fall by at least 24% from 1990 levels to meet the UK’s ambitious goal, which is reaching net-zero emissions. The originality of this paper is to apply the building typology approach to predict energy savings of the UK housing stock under a step-by-step energy retrofit scenario, targeting the Passive House Standard for refurbishments of existing buildings, namely the EnerPHit “Quality-Approved Energy Retrofit with Passive House Components.” The typologies consist of twenty reference buildings, representative of five construction ages and four building sizes. The energy balance of the UK residential buildings was created and validated against statistical data. A building stock retrofit plan specifying the order in which to apply energy efficiency measures was elaborated, and energy savings were calculated. The predicted total energy demand for the UK residential building stock for the year 2022 is 37.7 MTOE, and the carbon emissions estimation is 65.33 MtCO₂e. The energy-saving potential is 87%, and carbon reductions are about 76%, considering all the steps of renovation applied. It has been demonstrated that the step that provides the biggest savings across the housing stock is the one that involves replacing windows, draught-proofing, and installing mechanical ventilation with heat recovery.

Energy retrofit tools are considered by many countries as one of the strongest incentives to encourage homeowners to invest in energy renovation. These tools help homeowners to get an initial overview of suitable retrofit measures. Although a large number of energy retrofit tools have been developed to inspire and educate homeowners, energy renovation by individual homeowners is still lagging and the impact of current tools is insufficient as awareness and information issues remain one of main obstacles that hinder the uptake of energy retrofitting schemes. This research extends the current knowledge by analysing the characteristics of 19 tools from 10 different countries. The selected tools were analysed in terms of energy calculation methods, features, generation and range of retrofit measures, evaluation criteria, and indications on financial support. The review indicates that: (1) most toolkits use empirical data-driven methods, pre-simulated databases, and normative calculation methods; (2) few tools generate long-term integrated renovation packages; (3) technological, social, and aesthetic aspects are rarely taken into consideration; (4) the generation of funding options varies between the existing tools; (5) most toolkits do not suggest specific retrofit solutions adapted to traditional buildings; and (6) preferences of homeowners in terms of evaluation criteria are often neglected.

Applying circular economy principles to the renovation of existing buildings is increasingly recognized as essential to achieving Europe’s climate and energy goals. However, current decision-making frameworks rarely integrate life cycle carbon assessment with multi-criteria evaluation to support circular renovation strategies. This paper introduces an innovative framework that combines life cycle carbon assessment with multi-criteria decision analysis to identify and sequence circular renovation measures. The framework was applied to a residential case study in the Netherlands, using IES VE for operational carbon assessment and One Click LCA for embodied carbon assessment, with results evaluated using PROMETHEE multi-criteria analysis. Renovation measures were assessed based on operational and embodied carbon (including Module D), energy use intensity, cost, payback period, and disruption. The evaluation also introduced the embodied-to-operational carbon ratio (EOCR), a novel metric representing the proportion of embodied carbon, including Module D, relative to operational carbon savings over the building’s lifecycle. The homeowner’s preferences regarding these criteria were considered in determining the final ranking. The findings show that circular insulation options involving reused materials and designed for disassembly achieved the lowest embodied carbon emissions and lowest EOCR scores, with reused PIR achieving a 94% reduction compared to new PIR boards. The impact of including Module D on the ranking of renovation options varies based on the end-of-life scenario. The framework demonstrates how circular renovation benefits can be made more visible to decision-makers, promoting broader adoption.

Many retrofit projects went wrong in the UK principally because of the application of inappropriate retrofit solutions, which resulted in damp issues, with some leaving houses in worse conditions than pre-retrofit. Various online tools were developed to inform homeowners about the benefits of retrofitting. Prior to this study, little was known about users’ evaluation of these tools and the effects of calculator use. Furthermore, no retrofit tool aims to raise the awareness of homeowners about moisture risks in a retrofit project. The originality of this study is to develop and evaluate an online moisture-safe retrofit decision-making tool for homeowners. The adopted methodology consisted of two phases. Phase one aimed to develop the tool. In phase two, semi-structured interviews were conducted to evaluate the tool. The results indicate that the tool has been well received by homeowners. The tool significantly increased participants’ awareness of moisture risks related to a retrofit project. Most participants considered the tool an eye-opener, while few of them found it scary. However, the tool did not result in an increased willingness to invest in energy efficiency measures. The discouragement was related to high investment costs and long payback periods of some retrofit measures. Based on our findings, we formulate a set of design recommendations to improve the proposed tool and help retrofit calculators, in general, overcome challenges.

The construction sector is responsible for a significant share of greenhouse gas emissions in Europe, making the decarbonisation of the existing building stock a critical priority. In this context, Digital Building Logbooks (DBLs) are increasingly promoted as digital tools to support renovation planning, data continuity, and circular economy practices across the building lifecycle. Despite growing policy attention, the adoption of DBLs in renovation projects remains limited in practice. This study provides one of the first empirical rankings of perceived barriers, benefits, and drivers influencing DBL adoption in renovation projects across Europe. An exploratory quantitative survey was conducted with a purposively selected sample of stakeholders involved in renovation-related activities. Likert-scale responses were analysed using descriptive ranking statistics and reliability testing, while qualitative data from open-ended responses were analysed using directed content analysis. The results indicate that stakeholders strongly recognise the benefits of DBLs, particularly in terms of improved access to reliable building information, informed decision-making, and support for circular renovation practices. However, adoption is constrained by regulatory uncertainty, limited awareness, and unclear governance and operational frameworks. The most influential drivers identified relate to interoperability with existing digital tools, rising awareness of DBLs among stakeholders, regulatory support, and the availability of standardised and operationally clear frameworks for DBL implementation.

The building sector plays a central role in achieving global decarbonization targets, yet the implementation of high-performance energy renovation standards such as EnerPHit remains constrained by fragmented workflows and limited integration with digital processes. This study proposes a BIM-supported, performance-driven renovation framework that systematically integrates EnerPHit requirements within an Open BIM environment adapted to the Algerian context.,The methodology adopts a milestone-based approach, structuring the renovation process into sequential phases, including strategy definition, data collection, As-Built modeling, BIM-to-BEM integration, energy performance assessment, and energy design. This structured workflow enhances information management, stakeholder coordination, and continuous verification of performance objectives in accordance with ISO 19650 principles. Unlike existing approaches, the proposed framework ensures direct interoperability between BIM and energy modeling through standardized data exchanges, improving model continuity and reducing redundancy.,The framework is validated through a case study of a secondary school building in Tlemcen. Results show that envelope retrofitting measures, including façade and roof insulation and window replacement, significantly improve thermal performance and enable compliance with EnerPHit requirements.,The proposed approach provides a reproducible and scalable methodology that bridges the gap between performance-based energy standards and BIM-driven workflows, supporting sustainable renovation practices in Algeria and similar contexts.