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Purpose Decarbonizing cities is one of today’s biggest challenges. In this regard, particular attention has been paid on improving the environmental performance of buildings. In this framework, this work consists in assessing the environmental impact of an innovative building envelope component derived from urban agriculture (UA) wastes. In fact, rooftop UA seems to be a possible solution to the rising food demand due to increasing urban demographic growth. Consequently, rooftop UA wastes need to be treated in sustainable ways. Methods This study aims to determine the carbon footprint and embodied energy of a new infill wall material, derived from UA wastes produced by a building rooftop greenhouse tomato crop, and evaluate the potential biogenic carbon that such by-product could fix temporally until its end of life. After an initial description of the manufacturing process of the new material, its carbon footprint and embodied energy have been calculated by means of the life cycle assessment (LCA) methodology according to the ISO 14044 and the ISO 14067 guidelines adapted to the analyzed context. In particular, the inventory analysis is based on data collected from the production of samples of the new material at the laboratory scale. Results and discussion The results of the LCA indicate that, when the biogenic carbon fixed in the UA wastes is considered, a negative carbon footprint of − 0.2 kg CO2 eq. per kg of material can be obtained. Hence, it can be assumed that from a life cycle perspective the material is able to fix carbon emissions instead of emitting them. Specifically, for the considered scenario, approximately 0.42 kg CO2 eq./m2 per year could be sequestered. However, the crop area required to produce enough waste to manufacture a unit of material is quite high. Therefore, future studies should focus on individuate solutions to reduce the density of the new component, and also different urban crops with higher waste production rates. Conclusions The outcomes of the study put in evidence the potential of the new proposed infill wall component in fixing carbon emissions from UA, allowing to also compensate those relating to the production and transportation stages of the component life cycle. Moreover, producing by-products with UA wastes, hence temporally storing the carbon fixed by crops, may contribute to reduce the carbon cycles speed conversely to traditional waste management solutions, other than lower new raw materials depletion.

The management of municipal solid waste is a crucial issue to address as we move toward the decarbonization of urban contexts. Not by chance, this sector plays a relevant role in the Covenant of Mayors program, whereby municipalities are called to design their own Sustainable Energy Action Plans (SECAPs). However, despite new regulations strongly pushing the recycling and reuse of materials contained in municipal waste, many cities still use large landfills. As part of the overall environmental pressure exerted by these urban systems, the transport of waste from collection points to landfills or treatment facilities must be considered in order to correctly assess the full environmental burden of waste management. To this aim, in this paper, the Ecological Footprint method is applied to the municipal solid waste management system of the city of Palermo (Sicily). The results show that the impacts produced by the means of transport used, both in the status quo and in the assumed enhanced scenario (with less municipal waste disposed to landfills in favor of recycling), are significant compared to those caused by the other segments of the waste management system. The concept of a “saved footprint” is also introduced here, in order to properly compare the two scenarios.

Green roofs are widely used in hot or cold climates mainly because they are capable to improve the energy efficiency of buildings and, when implemented at a large scale, reducing air pollution and the urban heat island effect (UHI) in urban contexts. Artificial Neural Network (ANN) black-box algorithms are a valid alternative to studying complex systems. However, the literature highlights - quite surprisingly – none of the available research refers to coupling ANNs and green roofs in the Mediterranean area, where green roofs are instead considered one of the most suitable technologies to reduce the high cooling demand. Therefore, the objective of this research work is to create and validate an ANN for the prediction of the monthly green roof’s internal and external surface temperatures and the monthly internal air temperature, starting from different green roof parameters and climatic variables. Specifically, the ANN was created with reference to a Mediterranean climate considering an existing green roof on a building of the University of Palermo characterized by a cooling demand predominance; 180 green roof configurations, obtained by varying the characteristic parameters of vegetation (plant height, leaf area index and leaf reflectivity) and the substrate thickness and thermophysical properties (lightweight and heavyweight), were dynamically simulated on an hourly basis to build the training dataset. In addition, other 72 green roof configurations were simulated to generate the dataset for the validation purpose of the ANN accuracy. The optimal ANN-related architecture consists of 90 neurons with one hidden layer and guarantees very high accuracy predictions. The outcomes of this research represent a useful tool to determine the thermal response of green roofs and their impact on the building energy demand and indoor thermal comfort and UHI mitigation.

Recent regulations, and related incentives, concerning urban sustainability issued at European and national level place particular attention on improving the energy and environmental performance of buildings. In this sense, a particular focus has been placed on public buildings (offices, schools, hospitals, etc..), being these centers of gravitation of social life. Among the EU strategies on this matter is an initiative called Sustainable Energy and Climate Action Plan (SECAP), through which local administrators, based on the knowledge of their territory, are called to establish appropriate energy strategies and commit to achieving their targets within the timeframe set by the EU. The present paper contribute to this specific topic by means of a case study concerning the retrofit of a Sicilian office building, for which a comparison between the actual energy consumption and CO2 emissions, based on bill reading, and those consequent to the implementation of some SECAP selected energy improvement intervention, estimated through building dynamic simulation, was performed, taking into account also the economic aspects.

Green infrastructure in urban environments provides a wide range of ecological, social, aesthetic, and health co-benefits. Urban plant covers in particular contribute to improved outdoor environmental conditions that, in turn, influence the energy behavior of buildings and their indoor thermo-hygrometric comfort performance. Within this context, this study illustrates a methodology aimed at verifying the economic feasibility of alternative types of green areas for public and private stakeholders, which are analyzed as passive energy measures. Therefore, our methodology integrates approaches from different disciplines and consists of a microclimatic analysis of different vegetation scenarios and of the outdoor comfort level, an evaluation of the energy needs of a sample of houses, and an economic feasibility estimation considering different scenarios and public and private investors. The methodology is illustrated through its application to a suburban district of the Sicilian city of Trapani in the South of Italy, considered representative of Mediterranean climate conditions. Results showed significant differences between the scenario outcomes depending on the type of vegetation used in the green areas and put in evidence how economic feasibility for some stakeholders may be achieved in the management phase if adequate incentives equal to the planting cost are assumed.

The rapid and widespread deployment of green roofs requires the need to address their disposal and to assess the environmental impact of this phase of their life cycle to understand whether their current large-scale application may pose a problem. A review of the literature on green roofs environmental performance (particularly Life Cycle Assessment studies) has highlighted the lack of a standardized, commonly adopted, procedure for determining the treatments, recovery and/or disposal, to be assigned to waste from the removal of green roofs. In this regard, it should be mentioned that there is a lack of ad hoc legislation on the disposal of this technology (to the best of the authors’ knowledge, even at the international level). In this paper, an attempt procedure is introduced to identify the end-of-life scenario of green roofs that does not conflict with the current regulations regarding wastes. Specifically, the procedure relies on an “attempt classification” of the waste from individual green roof elements and the priority criterion for intervention. This procedure might thus be used temporarily by technicians, pending the issuance of guidelines specifically dedicated to green roofs disposal, to model their end-of-life and thus assess the environmental impact of this phase of the life cycle. The feasibility of this proposal was verified through a field application. Besides the methodological proposal, the results of the work indicated the need to review the current waste legislation and update it -at least the Italian one - to also consider new materials used in green transition technologies.

The constant push toward higher energy and environmental quality buildings makes the acquisition of excellence marks for products and materials, of which the building envelope is constituted, increasingly urgent. The recent European (EU) Commission Decision 2021/476 is applicable to marble used in construction. It sets out criteria that companies producing marble have to accomplish to obtain the EU Ecolabel brand. Unfortunately, some criteria such as, for example, those that refer to the application of the Environmental Management System, ISO 14001 and EMAS certifications, or those that concern the ISO 14067 as well as the Product Environment Footprint procedure, are difficult to apply for companies in the marble extraction and processing sector. These companies, in fact, are usually family-run and find it difficult to adhere to such complex schemes. This difficulty obviously limits the number of companies and products that can aspire to an environmental excellence label. On the other hand, the new Decision seems inadequate to identify the environmental impact of the transport of material between the different workstations of the same company; aspect that would be important to consider to evaluate in a broader and more detailed way this impact in the framework of the attribution of an environmental excellence label. To provide a contribution to overcome these difficulties for the companies and to open a debate on the criteria that lead to the assignment of the EU Ecolabel brand, here an alternative simplified method for the indirect assessment of pollutant emissions from the work chain of marble companies, which also includes the contribution of the transport phase of the semi-finished material between the different workstations of the company, is proposed. The method simply starts with an evaluation of the type and quantity of energy sources used in the work cycle and the emission factors of the main pollutants emitted. In this way, a sort of material impact sheet is obtained that contains not only the embodied energy of the marble but also the “embodied pollution” associated to it. The method, besides being easy to use, could be adopted in the criteria that lead to the attribution of the EU Ecolabel brand to companies that work marble.