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The renewed attention paid to raw earth construction in recent decades is linked to its undoubted sustainability, cost-effectiveness, and low embodied energy. In Italy, the use of raw earth as a construction material is limited by the lack of a technical reference standard and is penalised by the current energy legislation for its massive behaviour. Research experiences, especially transoceanic, on highly performative contemporary buildings made with natural materials show that raw earth can be used, together with different types of reinforcements, to create safe, earthquake-resistant, and thermally efficient buildings. On the basis of experimental data of an innovative fibre-reinforced rammed earth material, energy analyses are developed on a rammed earth building designed for a Mediterranean climate. The paper focuses on the influences that different design solutions, inspired by traditional bioclimatic strategies, and various optimised wall constructions have in the improvement of the energy performance of the abovementioned building. These considerations are furthermore compared with different design criteria aiming at minimising embodied carbon in base material choice, costs, and discomfort hours. Results have shown the effectiveness of using the combination of massive rammed earth walls, night cross ventilation, and overhangs for the reduction of energy demand for space cooling and the improvement of wellbeing. Finally, the parametric analysis of thermal insulation has highlighted the economic, environmental, and thermophysical optimal solutions for the rammed earth envelope.

The increase of the urban warming phenomenon all over the world is gaining increasing attention from scientists as well as planners and policymakers due to its adverse effects on energy consumption, health, wellbeing, and air pollution. The protection of urban areas from the outdoor warming phenomenon is one of the challenges that policy and governments have to tackle as soon as possible and in the best possible way. Among the urban heat island mitigation techniques, cool materials and urban greening are identified as the most effective solutions in reducing the urban warming phenomenon. The effects produced by the adoption of cool materials and urban forestation on the urban microclimate were investigated through a computational fluid-dynamic (CFD) model. The CFD model was calibrated and validated thanks to experimental surveys within the Catania University campus area. The urban microclimate thermal comfort analysis and assessment were carried out with the Klima–Michel Model (KMM) and Munich Energy Balance Model for Individuals (MEMI). In particular, three scenarios were performed: cool, low, and high levels of urban greening. The cool scenario, although it produces air temperature at around 1.00 °C, determines the worst condition of outdoor thermal comfort, especially at the pedestrian level. On the contrary, a high level of urban greening, obtained by the extensive green roofs together with an urban forestation, guarantees the wellbeing of pedestrians, showing more convenient values of PMV and PET.

This paper discusses the potential effectiveness of different green-based strategies for the mitigation of the Urban Heat Island effect and the consequent thermal discomfort in a crowded urban area located close to Catania, Southern Italy. The proposed mitigation solutions rely on the introduction of greenery systems either at a building scale or at an urban scale, namely: (i) green walls, (ii) green roofs and (iii) introduction of trees and urban vegetation at street level. The study relies on numerical simulations performed through ENVI-met, and aims to quantify the reduction in the outdoor air temperature and the outdoor Mean Radiant Temperature, as well as the variation in the wind speed and the relative humidity. The simulations refer to a 200 m square urban area, but the selected strategies just apply to a series of buildings in a smaller area located in the middle of the entire simulation domain. The results of the simulations suggest that the two solutions applied at the building scale do not introduce visible mitigation effects at the street level (that is to say at a height of 1.5 m above the street surface). On the contrary, significant improvements are observed with the extensive use of different species of trees along the streets and in the squares: indeed, the outdoor air temperature decreases by around 0.5 ℃ or even 1 ℃ at street level compared with the current state, especially in the hottest hours of the day. However, further simulations with ENVI-met suggest that green roofs and green walls are very effective to mitigate the indoor climate in summer. Hence, a suitable combination of the three proposed solutions is the most interesting approach for addressing both indoor and outdoor comfort issues.

The detailed analysis of the urban microclimate calls for the use of Computational Fluid Dynamics (CFD) tools able to model complex heat and mass transfer mechanisms. ENVI-met is one of the most used and reliable tools for microclimate analysis if an accurate calibration is performed. The calibration process is fundamental to have a reliable model in order to perform microclimate analysis, but requires accurate on-site measurements of urban weather data and it is usually difficult to have urban meteorological data of the required granularity because of the lack of on-site stationary weather stations. To overcome such an issue, this paper explores the use of weather data retrieved from suburban meteorological stations and morphed for the urban context under study through the Urban Weather Generator (UWG) tool. UWG generates an urban weather file in the hourly .epw format that is eventually used for forcing the ENVI-met model of the investigated area. This approach is validated against on-site measurements at different times for various points located in a district of the city center of Catania (Italy). The validation process presented a very good correlation for most of the study points in the district during nighttime, while during daytime some discrepancies may occur.

A strategy for improving the buildings energy efficiency is to diminish the energy demand for space heating and cooling. The European Directive has established a high standard of thermal insulation, involving stringent limits for building energy performance. However, such approach determines an increase of the cooling energy demand and noteworthy overheating of indoor spaces in the summer period. This study investigates through dynamic thermal simulations the effectiveness of new thermal insulation materials, such as Vacuum Insulation Panels (VIPs) and Phase Change Materials (PCMs), on reducing heating and cooling energy demands, as well as guaranteeing the thermal comfort into a test room located in three different locations (Catania, Rome and Wien). The energy demand for space cooling and heating have been evaluated for the different facade configurations, as well as the attainable indoor thermal comfort. The outcomes of the simulations in air-conditioned spaces highlight that the wall configurations that adopt VIPs allow reducing the heating energy needs but may increase the cooling energy needs. Remarkable differences are not detected for the heating and cooling energy demands when the PCMs are used. The daily fluctuation of the indoor operative temperature and the adaptive comfort model suggest that the PCM placed on the inner side of the walls shows a good thermal performance. The outcomes of the study outline the strengths and weakness of the analyzed facade configurations, which may help designers in the search for suitable solutions.

Developing nearly Zero Energy Buildings (nZEB) represents a path toward sustainable communities as required by the Energy Performance of Building Directive (EPBD). As consequence, nZEB target for new or existing buildings has become a mandatory priority for the multidisciplinary researchers involved in architectural engineering and building physics. Therefore, it is grown the interest in design energy efficient measures for reaching the nZEB status of both new and existing buildings. In this paper, the energy efficient measures adopted for reaching the nearly Zero Energy Building standards, for a multi-floor residential building located in the Mediterranean area, are presented. The extra cost necessary to reach the nZEB target have been calculated in the case of the energy retrofit of an existing building (scenario 1) and in the case to directly realize a building with achieve the nZEB status (scenario 2). Further, the two scenarios have been compared under financial point of view. The results of this paper provide to builders and stakeholder useful information for quantify the convenience to build a nZEB building in advance in order to prevent the additional expenses necessary by future energy retrofit programs.

The growth in global trade and freight distribution has led to an increased demand for new containers and has caused immense leftovers of shipping containers at ports due to the expensive repositioning cost. These abandoned containers have a strong environmental impact. However, this is an issue that can be overcome by re-using shipping containers as homebuilding. Therefore, this research investigates the energy performances of container houses applying well-established Passivhaus standard which at the same time providing low environmental impact and a high level for occupant comfort.

The progressive modification of the land surface in the urban area during the last decades has involved an increase in urban air temperature compared to surrounding rural areas. The significant replacement of green areas with built surfaces characterized by high solar radiation favored the energy storage during the day and heat release in the nocturnal hours. The Urban Heat Island (UHI) is an emblematic effect of the increase of urban temperature which in turn affects the energy consumption in the building sector. Several passive building technologies are available to mitigate the UHI phenomenon and reduce the energy consumptions in buildings. In the Mediterranean climate, where the solar radiation control is the most important passive strategy in summer, cool roof technology is able to reduce the solar radiation absorbed by materials and to limit the outer superficial temperature in the presence of high solar loads. This paper presents a numerical analysis of the energy and environmental performance of an office building equipped with a cool roof for three different climate zones. Dynamic simulations highlight the different thermal behavior of the investigated cool roof in comparison to the standard roof, also as a function of the roof thermal resistance. Moreover, the Solar Reflectance Index (SRI) of the different roof configurations has been evaluated. It was found that slight or no insulated cool roofs has the lowest superficial temperatures and hence mitigates the UHI.

In recent years, the demand for air conditioning systems has increased considerably. Consequentially, the energy demand for building cooling has become a serious concern. In particular, the energy peak demand that is intensified by the urban heat island (UHI) effect is often a critical issue for the outdated electricity infrastructure in many countries. In order to rationalize the building energy consumption while ensuring indoor thermal comfort, this paper explores the possibilities offered by the retrofitting of existing uninsulated roofs in combination with night natural cooling strategies. To this end, a case study was selected in order to investigate the performance of an extensive green roof (GR) with and without natural ventilation (NV). The selected building is located in Catania, southern Italy, in a very mild climate. Free-running conditions were evaluated together with air conditioning conditions during the daytime and free cooling via natural ventilation at night. The hourly variation ...

The current increase in the price of fossil fuel and, consequently, of energy, and the decrease in the availability of these resources, led to the enactment of laws, among which the European Directive 31/2010 on Net Zero Energy Buildings (NZEB), with more strict limits on energy needs. So it is grown the interest in constructive solutions and equipments to reduce heat losses and the energy demand for heating, as well as the study to reduce energy needs for cooling and lighting in order to obtain a zero or nearly energy building. This study aims to identify solutions for zero energy building design and investigates some construction technologies and equipments in order to optimize the energy performance and to reduce the environmental impact of residential buildings. A simulation tool was used for the investigation of the feasibility of NZEB applied to a case study.

The continuous city growth leads to the intensification of the Urban Heat Island effect (UHI) which involves several consequences for the in-habitant comfort. Countermeasures such as green roofs can mitigate the urban microclimate reducing the roof surface temperature and hence the surrounding air temperature. As most of the existing Italy building stock was built without or with poor thermal insulation, they need of interventions of energy retrofit. In particular, roofs are the component of the building envelope that are mainly engaged of both solar gains and thermal fluxes. Therefore, any interventions refurbishment should include the roof surface. This paper focuses on the analyses of the energy performance and the dynamic thermal behavior of a green roof implemented in an existing house-holiday situated in the south part of Sicily. Moreover, other two refurbishment scenarios that foresee the increase of the roof thermal insulation were analysed. Dynamic simulations have proven that the green roof reduce the energy needs, about 90% in the cooling period and 30% in the heating period; delays and attenuates the outdoor heat wave in comparison with traditional roofs, as well as diminishes the average daily temperature fluctuations. The reduction of the vegetated temperature area results about 10.0 °C lower than the one of a bare roof area.

This paper presents a geographical information method to support urban-level energy policies. It proposes using a geographical information system to store, display, edit, share and analyse geographical information for territorial decision-making. The method was used to help develop a sustainable energy action plan for the municipality of Randazzo in Sicily, Italy, by providing an accurate representation of actual energy consumption. Based on this case study, the use of a geographical information system appears to be a suitable support tool for both developing and managing sustainable energy action plans, regardless of the geographical area or context. This method will help municipalities estimate and monitor the energy consumption of residential, commercial and industrial buildings and, by taking into account the approaches of different stakeholders, help develop more accurate models for reducing urban carbon dioxide emissions.

Nowadays the concept of Net ZEB is well-known and widespread in the scientific community. The European Union has set ambitious targets for 2020 and even more ambitious for 2050. In order to reduce the domestic GHG emissions by 80–95%, compared to 1990 levels-till 2050, the building sector has to do its part and to pass through a deep restructure. Therefore, it is grown the interest in design and technical solutions for achieving a zero or nearly zero energy building. This paper investigate several construction technologies and system of energy production that can be adopted to build an “enhanced saving” (parsimonious) building, which can strive for the objective of NetZEB. Moreover the economic analysis of the feasibility of the NZEB target has been developed.

The reduction of energy demand for space cooling, as well as the mitigation of the Urban Heat Island effect (UHI), require adequate solutions at building and urban scale. In particular, the roofs of buildings have been identified as a possible field of intervention that could contribute to provide significant energy savings and environmental benefits. In this context, cool and green roofs are two very interesting solutions, which may allow obtaining both the reduction of the energy consumption and the improvement of the comfort sensation in the outdoor and indoor environment. This paper presents a numerical comparative analysis of the energy and environmental performance of three typologies of roof, namely a standard roof (SR), a cool roof (CR) and a green roof (GR). This analysis, developed through dynamic energy simulations under temperate climate, highlights the different thermal behavior for the investigated roof scenarios, also as a function of the level of thermal insulation. Moreover, with the aim to obtain a classification between SR, CR and GR in Mediterranean climate, a scoring system is presented, which considers the whole performance of the investigated roof scenarios under a broad perspective. As a result, it is found that green and cool roofs provide higher energy savings and environmental benefits than highly insulated standard roofs. In particular, scarcely insulated green roofs showed the best performance in relation to the UHI mitigation under the climatic conditions typical of the Mediterranean area.

The energy policies about energy efficiency in buildings currently focus on new buildings and on existing buildings in case of energy retrofit. However, historic and heritage buildings, that are the trademark of numerous European cities, should also deserve attention; nevertheless, their energy efficiency is nowadays not deeply investigated. In this context, this study evaluates the thermal performance of a traditional massive building situated in a Mediterranean city. Dynamic numerical simulations were carried out on a yearly basis through the software DesignBuilder, both in free-running conditions and in the presence of an air-conditioning (AC) system. The results highlight that the massive envelope of traditional residential buildings helps in maintaining small fluctuations of the indoor temperature, thus limiting the need for AC in the mid-season and in summer. This feature is highly emphasised by exploiting natural ventilation at night, which allows reducing the building energy demand for cooling by ...

Green roofs have several environmental benefits, such as improving building energy efficiency. As the existing Italy building stock was built before any roof insulation was required, the existing buildings will benefit most by the green roofs. The exploitation of a green roof for retrofitting of an existing house-holiday placed in the south part of Sicily was studied. The building energy performance and the dynamic thermal behavior of the green roof has been evaluated using a transient simulation program. The results of this study indicate a remarkable reduction both of the cooling and heating load respectively of about 80% and 34%. Dynamic simulations have proven essential that the typology of green roof investigated delays and attenuates the outdoor heat wave better of traditional roof diminishing the average daily temperature fluctuations. Therefore, the green roof shows a strong potential for the retrofit of not well-insulated building in Mediterranean area.