• Energy Research

Residential buildings consume a large fraction of energy and thus represent a major opportunity for reducing energy requirements and greenhouse gas (GHG) emissions. This article presents a life-cycle energy and GHG analysis of three representative residential building types in a well-known area in Lisbon (Bairro de Alvalade). The life-cycle model focused on building construction, retrofit and use phases, applied an econometric model to estimate energy use in Portuguese households, and considered two functional units: per square meter per year and per person per year. Over the buildings’ 75-year lifespan, the use phase accounted for most (69–83%) of the primary energy requirements and GHG emissions. Larger buildings have lower life-cycle energy requirements and GHG emissions on a square meter basis. On a per person basis, however, this pattern is reversed and larger buildings are associated with higher energy requirements and GHG emissions. Due to the considerable variability and uncertainty associated with life-cycle analyses of buildings, the use of both occupancy- and area-based functional units is recommended.

Dataset on LCA results of electricity generation and supply in Italy for 2018, 2019 and 2020 (current mix) and two future scenarios (2030) - Global Warming, average demand perspective. Modelling materials and methods are described in the paper "Life-cycle assessment of current and future electricity supply in Italy: addressing average and marginal hourly demand".

The increase in overall electricity demand in recent years, together with the rapid and significant changes in electricity generation has motivated increased research addressing environmental impacts of current and future electricity generation and supply systems. This article presents a comprehensive life-cycle assessment (LCA) of electricity generation and supply for the Italian current mix and future scenarios, for a wide set of environmental impacts and indicators, addressing intra-year variations, and including average and marginal demand impact perspectives. The generation mix was modelled for a 3-year period (2018–2020) with hourly and country-specific data, for the main generation technologies; and two future scenarios (for 2030) were modelled applying the EPLANopt energy system model. While future scenarios - with larger renewable energy shares - resulted in reduced environmental impacts in most categories, they were associated with burden shifts. In particular, increased shares of solar photovoltaic generation in future scenarios resulted in significant contributions to mineral and metal resource depletion and to land use impacts. The high penetration of renewable energy sources in future scenarios was also associated with important seasonal and hourly variations, demonstrating the importance of addressing intra-year temporal variations. Moreover, complementing an average with a marginal demand perspective provided insight on potential impacts of demand changes. When considering a marginal demand perspective, future scenarios offered no clear benefits in terms of global warming, for example. The research demonstrated the need for comprehensive and detailed environmental impact assessments with fine time resolution, which can assess seasonal and intra-daily variations, and the evaluation of environmental impacts with both average and marginal demand perspectives highlighted the complementary nature of the two in providing insightful results. The approach is fully replicable to other countries and regions - it can improve LCAs of electricity generation and supply and provide robust results to adequately inform decision-making on electricity generation and demand management, toward more sustainable energy systems.

Abstract Nowadays, debates addressing climate change, fossil fuels depletion and energy security highlight the need for a more sustainable built environment in order to reduce energy consumption and emission trends in the buildings sector. Meeting these targets is a challenge that calls for innovative research to improve the use of renewable energy sources, new technologies, and holistic tools and methodologies. Such research should integrate the dynamics and main drivers of energy supply and demand in buildings to support new policies, plans and actions towards lowering the built environment burdens. This paper brings together ten research topics concerning the energy and environmental performance of buildings, which can support a shift towards a more sustainable built environment. Background information and state of the art literature on the covered research topics is briefly summarized, gaps are identified and guidelines for future research are provided. The selected topics cover different stages along the lifetime of buildings (from design and operation, to retrofitting and end-of-life), different scale approaches (from building elements/components, to the building, district and urban scales), and different methods to assess the energy and environmental performance of buildings (life-cycle assessment, generative design methods and retrofitting tools). Other topics are discussed such as: nearly zero-energy buildings, the control of domestic energy resources in smart grid scenarios, the need to include end-users' behaviors in the dynamics of energy demand, the advantages of improving thermal storage by using phase change materials, the importance of reducing heating and cooling energy demand (maintaining indoor thermal comfort), and the optimization of heating and cooling fluids, and their system control.

While most life-cycle assessments of buildings have focused on construction and use phases, the location of a building can significantly affect the transportation demand of its inhabitants. The life-cycle energy and greenhouse gas (GHG) emissions of two representative buildings in Lisbon, Portugal, are compared: an apartment building in the city centre and a semidetached house in a suburban area. An integrated approach is used to conduct a life-cycle analysis that includes building construction, building use and user transportation. Sensitivity analyses are used to evaluate impacts for multiple locations. For the apartment, building use accounted for the largest share of energy and emissions (63–64%), while for the house, most (51–57%) of the energy and emissions were associated with user transportation. Energy and GHG emissions for suburban locations were significantly higher (by 55–115%) than those in the city-centre locations, largely due to individuals commuting by car. The analysis demonstrates the s...

The concept of Positive Energy District is one of the main areas of research and extensive applications of the principles of the clean energy transition within the building sector. In the past years, the most widely accepted definitions have focused specifically on carbon neutrality, while several other aspects regarding all sustainability approaches (including environmental, social and economic perspective) were included qualitatively or to a lesser degree. This paper proposes a discussion on the state of the art of the sustainability assessment of Positive Energy Districts, by investigating environmental, social and economic sustainability applications. The three sustainability dimensions are investigated individually first, while discussing methodological insights, key performance indicators used and quantitative results, as well as in an integrated perspective. Finally, the paper describes research gaps and areas for further development on the topic.

Abstract This paper brings together several contemporary topics in energy systems aiming to provide a literature review based reflection on how several interrelated energy systems can contribute together to a more sustainable world. Some directions are discussed, such as the improvement of the energy efficiency and environmental performance of systems, the development of new technologies, the increase of the use of renewable energy sources, the promotion of holistic and multidisciplinary studies, and the implementation of new management rules and "eco-friendly and sustainable" oriented policies at different scales. The interrelations of the diverse energy systems are also discussed in order to address their main social, economic and environmental impacts. The subjects covered include the assessment of the electricity market and its main players (demand, supply, distribution), the evaluation of urban systems (buildings, transportation, commuting), the analysis of the implementation of renewable energy cooperatives, the discussion of the diffusion of the electric vehicle and the importance of new bioenergy systems. This paper also presents relevant research carried out in the framework of the Energy for Sustainability (EfS) Initiative of the University of Coimbra, linking the reviewed areas to the multidisciplinary approach adopted by the EfS Initiative. To conclude, several research topics that should be addressed in the near future are proposed.