This research compares the potential environmental impacts of heat pumps with gas boilers and scenario analysis through utilising the life cycle approach. The study analyses the current situation with the baseline model and assesses future applications with Circular Economy (CE), Resource Efficiency (RE) and Limited Growth (LG) scenarios. Then, hybrid applications of low-carbon technologies and different manufacturing scenarios are investigated according to baseline and CE scenarios. Our results show that the use and manufacturing phases are responsible for 74% and 14% of all environmental impacts on average as expected. Even though the electricity mix of the UK has decarbonised substantially during the last decade, heat pumps still have higher lifetime impacts than gas boilers in all environmental categories except climate change impact. The carbon intensity of heat pumps is much lower than gas boilers with 0.111 and 0.097 kg CO₂e for air source heat pumps and ground source heat pumps, whereas the boiler stands as 0.241 kg CO₂e. Future scenarios offer significant reductions in most of the impact categories. The CE scenario has the highest potential with a 44% reduction for heat pumps and 27% for gas boilers on average. RE and LG scenarios have smaller potential than the CE scenario, relatively. However, several categories expect an increase in future scenarios such as freshwater ecotoxicity, marine ecotoxicity and metal depletion categories. High deployment of offshore wind farms will have a negative impact on these categories; therefore, a comprehensive approach through a market introduction programme should be provided at the beginning before shifting from one technology to another. The 50% Hybrid scenario results expect a reduction of 24% and 20% on average for ASHP and GSHP, respectively, in the baseline model. The reduction is much lower in the CE scenario, with only a 2% decrease for both heat pumps because of the reduction in heat demand in the future. These results emphasise that even though the importance of the use phase is significant in the baseline model, the remaining phases will play an important role to achieve Net-Zero targets in the future.

This study aims to create a comprehensive, holistic approach to evaluate the environmental, energy, and economic impacts of air source heat pump deployment scenarios through: (i) a life cycle assessment of air source heat pumps in Orkney houses, (ii) energy systems optimisation modelling to optimise the performance of an air source heat pump coupled with thermal energy storage tank to reduce use phase related impacts in Orkney, (iii) modelling of Orkney’s domestic building stock to understand the housing condition, and (iv) economic modelling to analyse the life cycle cost of an air source heat pump and potential savings when replacing conventional heating systems. The results show that an 82% reduction in energy supply could be achieved when ambitious energy efficiency improvement measures are adopted in the circular economy scenario. The use phase related emissions could be reduced by 98% when the air source heat pump becomes the only heating technology in Orkney. However, the life cycle-wide approach suggests that strong commitments are required in the manufacturing stage of these technologies through implementing circular principles, such as including the use of secondary materials, eco-design, and reusability of all components. Moreover, total heating costs paid by consumers in Orkney could be reduced by 84% in the circular economy scenario when air source heat pump uptake is coupled with energy efficiency improvement measures, but it requires a £130 million investment to insulate the whole housing stock of Orkney. Future scenarios indicate that decision-making has significant importance on overall results. Therefore, circular economy standards for air source heat pump manufacturing and deployment are crucial to reduce the negative impacts of fuel poverty and reach the net zero target.

An analysis of eco-innovations solutions for efficient low carbon buildings through circular economy principles (reduce, reuse, recycle), that also consider economic and social indicators has been performed at the national (Turkey) and urban scale (Kayseri). The framework for the city of Kayseri and the implementation of the circular economy for construction chain were determined that the three enabler tools which are policies, funding and awareness and collaboration could help to implement circular city model in Turkey. Reducing energy intensity and understanding the factors that can influence this (such as urbanization and industrialisation) will help mitigate future climate changes, improve local air pollution and health.

The transition to a circular economy requires reimagining waste as resource, particularly in post-disaster contexts where temporary infrastructure often becomes obsolete after its initial use. This study aims to operationalise a circular framework by repurposing nearly 215,000 container units from the 6 February 2023 earthquakes in Türkiye into affordable student dormitories. By designing a dual-use lifecycle, the research addresses the chronic shortage of university accommodation while ensuring these units remain maintained and ready for rapid deployment in potential future disasters. Using the Erciyes University campus as a case study, the methodology focuses on architectural strategies for modular retrofitting and the establishment of scalable site typologies. These designs integrate residential units with essential social and study areas, allowing for rapid implementation in diverse campus locations without requiring site-specific modification. Initial results indicate that the integration of high-standard units into permanent urban infrastructure secures the long-term economic value of the initial investment, with projections suggesting this model could yield 56.7 billion TL national savings. The research concludes that how circular strategies can transform disaster waste into resilient and permanent social infrastructure, contributing to Türkiye’s 2053 net-zero emissions target.

Artificial Intelligence (AI) has rapidly reshaped residential building energy research; however, the field lacks a data‐driven synthesis of its global structure and evolving themes. This study addresses this gap by combining bibliometric analysis with latent Dirichlet allocation (LDA) topic modelling to analyse 1368 articles (2020–2025) from Web of Science Core Collection (WoSCC) and Scopus. Results show a dramatic increase in publications within a global but uneven landscape: China and the United States (US) lead in volume, while Vietnam and Denmark produce the most influential outputs per paper. The United Kingdom (UK) maintains a balanced profile, and several EU member states, including Italy, Spain and Germany, rank among the leading contributors. Collaboration networks are primarily academic, with limited industry involvement. LDA identifies four main themes: energy performance modelling, HVAC optimisation, load forecasting and management and smart‐home energy management. Within these, research centres on operational applications and shows a methodological progression from conventional machine learning (ML) toward hybrid deep learning (DL), including emerging transformer‐based and graph‐based models. The analysis scale is expanding from single‐buildings to district‐level and interconnected systems. The comprehensive review identifies a persistent gap in occupant‐centric modelling and highlights the need for real‐time data integration and improved transparency to deliver practical, human‐responsive, and scalable energy efficiency solutions.