In recent years, many cities around the world have pledged to upgrade their building stocks to carbon-neutral. However, the literature does not yet provide a shared definition of carbon-neutral ...building (CNB), and the assessment objectives and methodological approaches are vague and fragmented. Starting from the available standards and scientific literature on life cycle assessment (LCA), this paper advances an operational definition for CNB on the basis of an explicit calculation approach. It then applies the definition to an urban case study, comparing it against a state-of-the-art nearly Zero Energy Building (nZEB) scenario, with the intent of highlighting the major practical limitations connected to the application of a methodologically sound carbon neutrality calculation. The case study shows that carbon neutral objectives can hardly be achieved by single urban buildings because of the lack of spaces that can provide onsite carbon offsetting actions. Carbon neutrality may be better approached at the city, regional, or national scales, where overarching policies may be defined.
Over the last decades, the reduction of the energy use in the building sector has become a topic of major investigation and policy development worldwide. Guidelines have been defined to drive ...governments and building construction stakeholders towards the retrofit of the existing building stock and to the construction of new high-performance buildings. However, availability of operational data is often limited, especially when it comes to high performance buildings in warm climates, although it is essential to define design approaches targeted to energy efficiency, to design smart energy grids and demand-response oriented energy programs. Buildings, such as living laboratories, may offer opportunities to implement and develop energy databases, to provide benchmarks and to study occupant behaviour under different operational conditions.
The paper investigates the energy and thermal comfort performance of a residential building in the Mediterranean climate. The building, certified as Passivhaus and equipped with an advanced monitoring system, allows to test different control strategies, to study occupant behaviour and to provide real time operational data. In particular, the data analysis showed a positive energy balance on yearly basis, i.e. an energy use of 59.7 kWh/m2net/year vs. an on-site energy generation of 76.0 kWh/m2net/year. The energy breakdown highlighted, that energy uses related to user behaviour and comfort requests account for about 72% of the total energy use, confirming that occupant behaviour is one of the major drivers of the operational energy use (and the related services) in high performance buildings.
•In UBEM buildings are usually modelled via archetypes with fixed occupants-schedules.•Data-driven occupants-related schedules randomly distributed are proposed.•The impact of these occupants-related ...schedules on UBEM results is assessed.•Data-driven schedules are significant if the analysis targets hourly or daily values.•Data-driven schedules are significant if the analysis targets 5 or fewer buildings.
In Urban Building Energy Models (UBEMs), buildings are usually modelled via archetypes describing occupants’ behaviour via fixed schedules. This research (i) creates data-driven schedules for electric use and occupancy from smart meter readings randomly distributed in the model to improve residential archetypes, (ii) assesses the impact of these schedules on UBEMs' energy results at different temporal resolutions and spatial scales. The novel assessment procedure exploits integrated heat maps based on coefficients of variation of the root means square error (CVRMSE). The outcomes show that differences in energy needs, with randomized schedules, range based on temporal and spatial aggregation. Yearly, for the entire neighbourhood, heating and cooling energy needs, and electric uses are estimated -2%, +1%, and +18% compared to the base case. The outputs show that, when simulations are focused on the entire district, fixed schedules can be enough to describe energy patterns. However, if the simulation is focused on small groups of buildings (e.g., 5 or fewer), randomising the schedules can create variability in the model in terms of electric use and occupancy among buildings characterized by the same archetype. The followed methodology can be exploited also with larger databases and eventually verified with also other types of data.
Different variables concur to the outdoor comfort assessment and, among them, the Mean Radiant Temperature (Tmr) represents the most challenging one to experimentally evaluate. According to the ...scientific literature, the most accurate method for in-field Tmr calculation is integral radiation measurements with three net radiometers. Nevertheless, net radiometers are expensive sensors and their implementation on large scale may be hindered by their price. To provide a cost-effective alternative some researchers proposed the use of globe thermometers. Globe thermometers are affordable sensors but typically exploited indoors, and their accuracy in urban settings is still under investigation.
The scope of this work is to provide information regarding the extent to which globe thermometers can substitute net radiometers in the evaluation of the Tmr in outdoor urban settings. To this purpose, an experimental comparison has been performed between the Tmr calculated using net radiometers, assumed as a reference, and using two different globe thermometers: a standard 150 mm black globe and a grey 50 mm globe.
The results revealed that the black globe tends to overestimate the Tmr while the grey globe mainly underestimates it. Moreover, the analyses evidenced a wide fluctuation in the profile of the Tmr calculated using globe thermometers, due to the rapid variation of meteorological parameters and the globes' long response time. To improve the fit between globe thermometers and net radiometers' response, regressive functions have been proposed, resulting in a significant enhancement of the adherence between Tmr calculated using the standard black globe's measurements and the reference Tmr.
•Tmr is key parameter for outdoor thermal comfort assessment in urban settings.•Globe thermometers cannot directly substitute net radiometers to assess the Tmr.•A regression equation is used to assess the Tmr from the standard globe thermometer.•In 90.4% of cases, the equation results in a negligible error for Tmr.•This result decreases greatly the cost and number of required sensors.
Increasing concerns over climate change and energy poverty have triggered the transition toward a decentralized energy system through the widespread adoption of renewable energy technologies. ...Although this transition was led, over past decades, mainly by major investors and large industrial players, citizens and local authorities are increasingly playing an active role in delivering clean energy investments. In particular, the current European Renewable Energy Directive introduced Renewable Energy Communities (RECs), which allow citizens to collectively organize their participation in the energy market, leading to a more distributed renewable energy system and new forms of sustainable, collaborative, and democratic economies. RECs currently under implementation show differences among European countries due to the different national contexts. A literature review exploring the peculiar Italian regulatory framework on RECs and its recent evolution has been carried out to identify available national and regional financial support mechanisms, barriers, and emerging trends in the diffusion of RECs across the country. The paper reviews and describes three main approaches that emerged in the development of RECs in Italy, discussing their strengths, and limitations. In addition, it provides a brief comparison of the regulatory framework in different European countries, highlighting the distinctive features of the Italian experience. Although the development of RECs in Italy involved a combination of both public and private initiatives, the leading role of local authorities as promoters and aggregators of RECs is evident. This role helps preserve the social impact of RECs but might slow down their implementation due to bureaucratic issues often linked to public procedures and procurement processes, as well as the lack of sufficient expertise within local authorities.
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