The development of an open-access, reliable database for embodied energy and carbon (dioxide) emissions associated with the construction industry is described. The University of Bath's inventory of carbon and energy database lists almost 200 different materials. The data were extracted from peer-reviewed literature on the basis of a defined methodology and a set of five criteria. The database was made publicly available via an online website and has attracted significant interest from industry, academia, government departments and agencies, among others. Feedback from such professional users has played an important part in the choice of 'best values' for 'cradleto-site' embodied energy and carbon from the range found in the literature. The variation in published data stems from differences in boundary definitions (including geographic origin), age of the data sources and rigour of the original life-cycle assessments. Although principally directed towards UK construction, the material set included in the database is of quite wide application across the industrial sector. The use of the inventory is illustrated with the aid of 14 case studies of real-world new-build dwellings. It was observed that there was little difference between embodied energy and carbon for houses and apartments until external works were taken into account (energy inputs for roads, connecting pathways, etc.).Energy analysis has been widely used since the first oil crisis of the early 1970s. 7 There are several different methods of energy Energy 161 Issue EN2Embodied energy and carbon in construction materials Hammond . Jones

The exergy method has been used to analyse changes in the structure of the UK energy system over a period of more than 30 years from 1965. A sectoral approach was employed, with the supply side examined in terms of themain energy sources, while final demand was separated into four energy end-use groups: the domestic, service, industrial and transport sectors. Estimates of sector-weighted or ‘lumped’ parameters, such as exergy efficiencies, were obtained from the particular characteristics of each sector. These were employed to determine the exergetic ‘improvement potential’ for critical elements of the energy system. Electricity generation together with final energy demand in the domestic sector and in transport are shown to account for nearly 80 per cent of the Second Law improvement potential. This poor thermodynamic performance is principally due to exergy losses in combustion and heat transfer processes associated with power generation, space heating and main transport modes. The results of the exergy analysis are placed in the context of recent developments in energy market liberalization and of the need to achieve environmental sustainability. They are also contrasted with proposals for new or improved energy technologies to meet the requirements of a sustainable energy strategy. Finally, the role of the exergy method is contrasted with the various other approaches to energy technology assessment.

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This paper describes the approach to developing transition pathways for a low carbon electricity system in the UK, being pursued in a major new interdisciplinary research project. The project aims (a) to learn from past transitions to help explore future transitions and what might enable or avoid them; (b) to design and evaluate transition pathways towards alternative sociotechnical energy systems and infrastructures for a low carbon future; and (c) to understand and, where appropriate, model the changing roles, influences and opportunities of large and small 'actors' in the dynamics of transitions. The paper describes the approach, which builds on the work of Dutch researchers on transitions and transition management using a multilevel framework of niches, sociotechnical regime and landscape, as well as on other parts of the innovation systems literature. It also describes its application to several outline transition pathways to a low carbon energy system in the UK. The pathways embrace both the evolution of the physical and institutional infrastructure changes and the roles of both large actors, e.g. multinational energy supply and distribution companies, national governments, major investors, and small actors, e.g. households, innovators and entrepreneurs.

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