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The building sector plays a crucial role in the advocated transition towards a carbon-free economy, and thus the zero-carbon building concept is taking hold. The paper focuses on the issue of existing hotels, with the aim of investigating the possibility of meeting the ambitious zero-carbon targets for this category of buildings, in which guests' comfort and satisfaction is the core business. A reference hotel and different retrofit scenarios are assessed in two Italian climatic zones. Models are evaluated with a multi-objective approach, by introducing a set of hotel-related Key Performance Indicators (KPIs), to evaluate the simulated models on three main dimensions: thermal comfort, energy and environmental impacts. The obtained results have emphasized the difficulty to achieve the zero-carbon targets, due to the high energy consumptions caused by the comfort-based nature of hotels and of the space constraints for on-site renewable sources. These outcomes help highlighting the need to shift the focus from single building to district or city scale, proving that the zero-carbon building definition must go hand-in-hand with the Post-Carbon City concept. • Transforming the built environment is fundamental to realize the Post-Carbon City. • Retrofit scenarios for an Italian Reference Hotel are modelled using EnergyPlus. • Scenarios are evaluated through multi-dimensional Key Performance Indicators. • Zero-carbon targets are still not tailored enough for comfort-based buildings. • A shift from building to district/city scale is needed to reach zero-carbon targets. [ABSTRACT FROM AUTHOR]

Although it is widely accepted that renewable energy consumption is vital for environmental sustainability, the environmental effectiveness of individual renewable energy types is often overlooked. Therefore, this paper examined the multivariate relationship between disaggregated renewable energy (hydroelectricity, wind, solar and biomass) consumption, economic growth and environmental pollution for the period from 1991 to 2014 in G-7 (The Group of Seven) countries. The study used both augmented mean group estimator and panel bootstrap causality method to consider the cross-sectional dependence and country specific heterogeneity across G-7 countries. Empirical findings indicate that increasing biomass energy consumption was efficient to reduce carbon emission in France, Germany, Japan and the United States; increasing hydroelectricity usage was efficient to reduce carbon emission in Italy and the United Kingdom; wind energy consumption reduced emission in Canada and solar energy usage was efficient on reducing emission in France and Italy for observed period. Moreover, in case of panel, it is found that increasing hydroelectricity, biomass and wind energy consumption reduced carbon emissions while the impact of solar energy consumption is statistically insignificant in G-7 countries. In addition, the hydroelectricity consumption was found the most efficient renewable energy source to reduce environmental pollution for the panel of G-7 countries. • Disaggregated renewable usage consumption and carbon emission nexus is investigated. • Increasing hydroelectricity usage reduces emission in Italy, the UK and the US. • Increasing wind energy usage reduces emission in all G-7 countries excluding Japan. • The effect of solar energy consumption on emissions is statistically insignificant. [ABSTRACT FROM AUTHOR]

Italy has reconsidered incentives on Renewable Energy Sources (RES) to implement the EU clean energy transition and Renewable Energy Communities (REC). Legislation on RECs shifted the focus of incentives from production to self-consumptions. In this paper, the REC model is studied in a minor island disconnected from the national grid, with strongly seasonal energy load and water demand. This is a typical Mediterranean scenario where energy demand is covered by Diesel gensets and water supply is provided with tankers. The implementation of RES is investigated, exploiting the current REC model of incentives. Two sub-optimal REC configurations were defined using time-dependent simulations on pyRES, an in-house code for energy systems. Results show the economical unfeasibility of REC when there is a poor mix of users. In contrast, REC can achieve economic profitability including industrial demand of a desalination unit (DES). The increase of self-consumption guaranteed from the DES allows to increase the NPV of the community and results in major cuts in CO 2 emissions (60% of those related to water supply and 10% of those from Diesel gensets) and a reduction of fuel costs of 22%. This method can be applied to investigate the performance of a REC in a local environment and help stakeholders in planning the expansions of RECs on the territory. [ABSTRACT FROM AUTHOR]