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—Despite the increasing concern of institutions and technical organizations toward the improvement of the building energy (and, therefore, environmental) efficiency, the main goal of technicians should be also devoted toward the levels of internal thermal comfort that buildings are able to realize. As that, the relationships between energy performances and comfort conditions provided by the enclosures are of paramount importance in guiding designers in their work. In this paper, the influence of diverse roof construction typologies on energy and indoor performance of buildings has been investigated, in different Italian sites during heating and cooling seasons. In addition, it must be properly considered that buildings operate in given climate and weather contexts that deeply affect their performances. Hence, for taking into account the different weather conditions of each site, a new parameter has been used, that is the “Climatic Severity Index” corresponding to a value of magnitude of a climatic vector less a constant value, recently released by an Italian technical standard. The actions for improving the energy efficiency sometimes lead to a reduction of indoor comfort, therefore, not always easily applicable.

Green roofs are building components that have become increasingly common in urban contexts because other than the general improvement of the aesthetics of the buildings equipped with them, they have demonstrated to positively improve the building energy performance. Consequently, it would be useful for technicians to have easy and reliable indicators to achieve a synthetic quantitative judgement about the effectiveness of green roofs by an energy perspective compared to others building envelope technologies, for different climates. In sight of the definition of such an indicator, or at least of its properties, some considerations aimed at this purpose, especially concerning the use of new climatic indicators instead of the commonly used ones (i.e. heating and cooling degree days), are presented here.

The improvement of the energy efficiency of building stocks represents an important contribution for the reduction of the energy consumption in the European Union (EU), along with the decrease of greenhouse gases emissions. In this aim both the public administrations and the technical experts need reliable calculation methodology to assess buildings’ energy performance. In this framework, despite the recent publication of the Standard EN ISO 52016, that deeply modifies the approach to the energy building simulation by introducing a new hourly dynamic calculation model, the current normative framework (EN ISO 13790) will maintain its validity until the incorporation of the new Standard in the national Standards and Decrees (such as the Italian Standard UNI/TS 11300-1) will take place. The aim of this paper is comparing the suitability of the simulation approaches proposed by the above-cited Standards in relation to their different levels of complexity and to the levels of details of the results provided by them. On purpose, a case study in which the energy behaviour of a public building, sited in the Sicilian city of Trapani in the South of Italy, will be analysed and the results of the simulations conducted according to the aforementioned Standards will be compared considering the outcomes of the EnergyPlus software as reference values.

Resilience represents a new important feature that the anthropic systems, and cities among them, are called to cope with. In fact, the increasing negative stresses to which urban contexts are exposed, and mainly the climatic pressures, call for the capability of adapting to these modifications and, possibly, to restore the ex-ante situations. The role of the buildings and their envelope components is of crucial importance to this aim. This paper analyses the features of resilience of the roofs of buildings by means of proper quantitative indexes. On purpose, the performances of green and cool roofs are compared. The possibility of adopting nonstructural solutions, like the windows shading devices, is also considered.

This paper reports the strategy implemented by the Palermo University (Italy) aimed at fostering the energy performance of its campus, particularly towards financing energy saving measures. The basic idea is that the money saved through the energy efficiency actions, constitute the main flywheel to fund further savings and energy efficiency interventions. Results of this paper might bring a useful contribution to the energy planning of cities, since campuses may be regarded as emblematic case study of what can be done in cities because they reproduce, at a little scale, the functioning of wider urban contexts.

Public Administrations are frequently entitled to intervene in building stocks with energy rehabilitation actions. Unfortunately, the monetary budget at their disposal is generally limited and, consequently, a prioritization criterion is needed to optimize its allocation. The classification of the building energy performance is increasingly used by Public Administrations for this purpose. Here we argue that a proper prioritization criterion should depend upon the potential subjects to which the rehabilitated buildings are given back. If the energy rehabilitation is conducted on buildings that will be assigned to new dwellers, it would be preferable to use the energy class – which is based on a standardized energy consumption – because a change of the building users will occur with a consequent plausible change of the building energy usage profile. Instead, if same dwellers will occupy the retrofitted building, a criterion based on a usage profile – that is actually the one established by these occupants – seems to be more appropriate. The priority orders of 23 buildings of the Sicilian stock, obtained using their energy class and real energy consumption, are presented and compared. Results show at which extent these two rankings differ, thus warning Public Administrations about prioritization criteria to adopt.

The energy retrofit of the existing building stocks is considered a preeminent strategy to lowering the energy consumption of the building sector. Other than the definition of the most successful combination of energy saving measures, the definition of a suitable ranking of all the buildings of the stock, on which implementing established energy retrofit measures, is quite a relevant issue. The most eligible criterion for prioritizing the buildings seems their energy consumption because it combines the building energy performance and their size. To investigate the role played by the building dimension in determining the order of priority of all the buildings of a given stock, this paper presents and compares different hierarchical orders of 25 existing buildings that were obtained with and without consideration of the size of the buildings. Results show that, when the size of buildings is covered in the calculations, the generated prioritized order differs significantly. In addition, it has found that the entity of the variations compared to the hierarchy that does not contemplate the size of buildings, is logarithmically correlated with the net surface. Additionally, some concerns have arisen regarding the role of the EP index for the building energy classification.

Several studies analyze the thermal performance of vegetated roofs, presenting either mathematical models or experimental quantifications of heat transfer process through them, also showing the effect of vegetation and soil parameters on the thermal and energy performance of this type of roofing system. However, presently the level of availability of these parameters, has not been enough considered. This work intends to investigate this underestimated issue of the green roofs’ thermal modeling, through the consideration of the availability of parameters pertinent to the shortwave radiation exchange, which are adopted by models based on leaf area index (LAI) and on the fractional vegetation coverage (σf). From the analysis of these models, the importance of a precise knowledge of such parameters arises, despite the availability of their values is still limited. In addition, the absence of a proper database including several green roof plant species and information on their stage of growth, to which a technician possibly will refer in the case of lack of field data, represents quite a worthwhile matter because it may lead to inaccurate estimations of the thermal loads for climatization of buildings equipped with green roofs. In this respect, the manuscript reports an estimation of the errors potentially occurring when not specific vegetation data are used. This evaluation is based on simulations, performed with the DesignBuilder© software, showing the energy effects produced by different assumptions in the green parameters (that is by adopting experimental data revealed by authors and a potential mix of the literature available parameters). Thus, the mission of the paper is to enlighten a difficulty that a technician possibly will encounter when performing an energy and thermal simulation of a green roof; therefore a strong call for making the current database more tailored on green roofs has also arisen.

The energy saving in building goes on as an important challenge in the policy of Developed Countries. While the issue of energy building efficiency in heating season has deeply been investigated for a long time, the issue of energy building efficiency in cooling season is relatively recent. Moreover, considering the increase of electric consumption for air-conditioning in summer, mainly due to the growing quality of life, the research of technologies for reducing energy building consumption during this season becomes essential. The green roof represents a technology useful to reduce the energy consumption during the cooling season. In this work the authors report the results of a monitoring campaign of temperature through a green roof that is installed in a building situ in a town close to Palermo, South of Italy.

Radiative heat exchanges inside buildings remarkably affect the thermal balance of the human body in confined spaces and the related thermal comfort sensations of people. The mean radiant temperature is an important component of this balance. Unfortunately, it is usually computed by means of too simplified relationships, which significantly influence the comfort evaluations. Such simplified approaches are also accountable for a less effective design of HVAC systems which, in turn, could result in high energy consumption in the climatization of buildings. However, an accurate evaluation of the mean radiant temperature, especially when high intensity sources are present in a given internal space, depends on the angle factors between human subjects and surrounding surfaces of the enclosure. Angle factors, in turn, are direct functions of the projected area factors of the human body. Presently, there is still a certain lack in the availability of simple and reliable methods for computing angle factors of people in assigned postures, particularly in case of complex geometry and presence of heat high intensity sources, like sun. A comprehensive method is here introduced for evaluating the thermal comfort conditions of indoor spaces, avoiding the difficult singling out of several algorithms, dispersed in an inorganic way in the literature. A further contribution consists in the possibility of evaluating geometrically complex enclosures also in presence of direct solar radiation entering the room. Moreover, an analytical method for computing the projected area factors, based on experimental results, obtained by means of a photographic apparatus on purpose designed, is included in the methodology. An application of the method to a typical building situation in presence of direct solar radiation is also proposed.

The world energy demand is continuously growing, which means an increase in consumption for all modern fuels or stronger effort on the development and improvement of renewable technologies. Moreover, Developing Countries claims more energy and they have often wide unutilized or unusable lands. The solar energy represents a useful opportunity for these Countries. The Solar Pond is both a solar collector and a thermal storage for long period and is suitable to use in wide sunny areas. Solar pond technology is able to supply heat for several applications requiring low-grade thermal energy or for electrical power production. In order to produce electrical energy from solar ponds it is necessary to use systems fed by low enthalpy sources, such Thermoelectric Generator (TEG) and Organic Rankine Cycle (ORC). In this paper, a model of a Solar Pond for power generation is analyzed in conjunction with an Organic Rankine Cycle. The model has been validated using climate data of an area near to Palermo city (Italy) and exactly the Test Reference Year developed by the Authors.

The energy efficiency interventions and rehabilitation actions regarding university campuses are characterized by an emblematic impact, representing significant examples of good practices that a given community could adopt, even at the city level. Starting from the idea that campuses may be regarded as small scale models of cities, a quantitative method for estimating to which extent the adoption of a given set of interventions by a municipality could contribute to make such city close to a nearly zero energy profile is proposed. To accomplish this task, the study considers the low carbon transition path of the campus of the University of Palermo and applies a simple method that, implementing an idea firstly developed by Yoshida et al. (2017), provides a rapid and effective graphical representation of the level of the success reached by the campus in terms of accomplishment of the nearly zero energy targets. The analysis of the transferability of such method to cities has shown that it can also be easily adopted by a city's administration and can be used for assessing the effectiveness of actions typically belonging to a city's energy policy, such as the public procurement and the waste management, apart from the actions regarding the public transportation system and the energy efficiency of the public building stock.

In this chapter, we try to connect the urban design features with energy consumption and consequent pollution parameters. After a review of a selected set of approaches to Urban Energy Systems study with a special focus on electrical power systems, urban energy systems are proposed as networks of multi-source hybrid energy hubs, where different energy flows are collected at the same bus and can be stored, delivered or transformed as needed. Resources at the hub and infrastructures interact with each other; therefore, both definition and boundaries of such energy systems at urban level are difficult to be clearly outlined. Similarly, the possibility to generate new operational models based on existing critical urban infrastructures is also challenging. This contribution proposes a preliminary study of urban energy hubs. Operations of thermal, electrical and mobility infrastructures are considered as qualifying features of the hub, but still the interconnected operation is not taken into account. The application part shows, indeed, the analysis and optimized design of the energy system serving two different urban districts. The related optimized parametric design of power generation infrastructures is considered as a function of urban features. The results about emissions and costs provide some interesting conclusions about the linkage between energy planning and urban features at district level, thus allowing, as possible application of this work, an energy-based territorial planning for urban contexts.

The paper provides a contribution for populating database of three physical parameters needed to model energy performance of buildings with green roofs: “coverage ratio” ( σ f ), leaf area index (LAI) and leaf temperature ( T f ). On purpose, six plant species were investigated experimentally: Phyla nordiflora, Aptenia lancifolia , Mesembryanthenum barbatus , Gazania nivea, Gazania uniflora , and Sedum . Proper ranges of the cited parameters have been found for each species. The here indicated ranges of σ f values refer to different growth levels of the species in the same lapse of time, that is four months. Single measured LAI values are also reported for the same plants. As for the T f (upper and lower layer), ranges of revealed temperatures refer to those detected from 10:30 a.m. to 16:30 p.m. of a selected day. Additionally, the dependence of T f on climatic parameters was investigated. A linear equation resulted the best fitting curve for all experimental T f data and the corresponding solar radiation data (with autocorrelation coefficients between 0.80 and 0.98). Furthermore, the effect potentially produced on building energy consumption by these species was analyzed using a simulation tool. Estimated cooling energy savings range approximately between 8% and 20% depending on adopted plants.