• Energy Research

AbstractRecently, great attention has been given to the transition from centralized to distributed generation energy production systems. There is a growing potential regarding the use of trigeneration systems in the residential sector because they have the ability to produce thermal energy and electricity from a single source of fuel.This study has the goal to determine the best systems able to satisfy the demand for electricity and thermal energy for a complex of historic buildings in Rome. Such analysis has been conducted using a specific tool conceived for energetic and financial analysis: the RETScreen software.

The importance of accurate lighting has been proven to be essential for good performance in all kinds of buildings, where most of the professional activities are carried out. National regulations and international standards dealing with indoor lighting establish the technical requirements of lighting installations to ensure the performance of their users. These requirements deal with illuminance on the working plane, uniformity, glare, color temperature of light and some other parameters. However, regulations and technical documents on indoor lighting are mainly referred to standard conditions that are sometimes far away from the reality. Hence, some installations can fulfill the technical requirements, whilst being uncomfortable for task development, impairing user’s performance and are oversized in terms of energy consumption. This work departs from a field study in highlighting the regulatory limitations in the matter of reflectance, to propose a quasi-Lambertian approach to real conditions in indoor workplaces with a special aim in educative environments. It consists of the introduction of “effective reflectance” coefficients for some key visual tasks and furniture carried out by users in certain typical positions and working planes. Based on this coefficient, it is proposed to implement a simple measurement and luminary programming methodology adapted to each particular workplace, especially in educational centers. The final target is to improve visual performance and save energy.

The smart and resilient city evolves by slow procedures of mutation without radical changes, increasing the livability of its territory. The value of the city center in a Smart City can increase through urban lighting systems: its elements on the territory can collect and convey data to increase services to city users; the electrical system becomes the so-called Smart Grid. This paper presents a study of smart lighting for a small town, a touristic location inside a nature reserve on the Italian coast. Three different approaches have been proposed, from minimal to more invasive interventions, and their effect on the territory has been investigated. Based on street typology and its surroundings, the work analyzes the opportunity to introduce smart and useful services for the citizens starting from a retrofitting intervention. Smart city capabilities are examined, showing how it is possible to provide new services to the cities through ICT (Information and Communication Technology) without deep changes and simplifying the control of basic city functions. The results evidence an important impact on annual energy costs, suggesting smart grid planning not only for metropolis applications, but also in smaller towns, such as the examined one.

Abstract In many emerging countries over the past few years some phenomena, such as a better welfare state, industrial growth and a development in agriculture, led to a significant increasing of the demand concerning fresh water. In order to face this ever-growing demand, one of the possible solutions to counterbalance the lack of water resources, is the desalination of sea water. For this specific goal solar energy, as a resource, is the process which has more reliance since it allows a low-cost production of desalted water (without using any valuable energy resources such as fossil fuels) and in a complete respect of the environment. This first study has the purpose to analyze from an energetic perspective whether it is possible or not to reach process temperatures over 100 °C, through the use of solar ponds and heat transformers, in order to produce desalinated water. The final aim of this work is to quantify the surface of solar ponds needed to a production (expressed in cubic meters) of desalinated water. An absorption heat transformer is a thermal machine that while extracting heat from a source (at an available temperature) is able to ennoble a portion of the heat collected/obtained, making it available at higher temperatures. This process occurs at the expenses of the remaining portion of heat whose temperature degrades by lowering its values. The portion of heat will be then transferred to a thermal well. Hence an absorption heat transformer can use the solar energy stored in solar ponds as an energy source at an average temperature. Process temperatures which are higher than 100 °C for a whole year can take place only under certain chained conditions such as: source temperature with steady values during the entire season obtainable through solar ponds; condensation process occurring at sufficiently low temperatures through the use of sea water; exertion of heat transformers. The heat which is usually available at these temperatures could be used for common thermal processes during the desalination of seawater. In this work we want to demonstrate that it is possible, energetically speaking, to produce desalinated water by exploiting the solar energy stored in solar ponds and the technology of absorption heat transformers. We can notice how for every m3 of desalinated water produced in one day we need ponds with an area ranging between 1000 and 4000 m2, this depends on the amount of heat flux drawn. The analysis we carried out represents a first attempt to face this kind of problem. In future studies we will examine both technical and economic feasibility.

In the last decades, lighting has evolved from a branch of engineering ensuring safety and performance in indoor and outdoor installations, to a key discipline interacting with a wide spectrum of fields and having a deep impact on our daily lives. Although this evolution also applies to other areas of knowledge, the special features of lighting make its potential and also its limitations different. It is not the typical field where a well-established mathematical framework allows a departure from well-defined input and identifying clear effects and conclusions. The reason is that lighting is a field dealing with the interaction between a physical phenomenon and a physiological and psychological system, the human being. In addition to the complexity of its basis, the relationship between lighting and sustainability has become stronger in recent years. This relationship is bi-directional in some cases: on one hand, advanced societies require more and more complex lighting installations, which means high energy consumption, use of raw materials, financial costs, manufacturing and maintenance processes, waste and emissions to the atmosphere. On the other hand, good lighting has an impact on issues like productivity, well-being, happiness, disease avoidance, safety, and many other qualitative aspects whose direct or indirect impact on sustainability is remarkable. This work will analyze how lighting can give answers to questions related to sustainability, not only from the classic topics of energy consumption and waste management, but from a wider and global perspective. The results of these works are analyzed, and the basis of the new framework of total lighting, discussed.

Abstract Climate change is considered an important global threat, with a significant impact on the energy performance, since buildings will be subjected to higher average outdoor temperatures. This article explores the relative impact of global warming across the different regional climates of Europe comparing present and estimated future energy needs of a hypothetical residential house located in 19 cities characterized by different latitude and Koppen-Geiger class. Building performance simulations with EnergyPlus are performed in order to simulate the heating and cooling needs of the building and the associated CO2 emissions in the present and in the future. The progressive increase in average temperatures in 2050 and 2080 leads to a general decrease of thermal energy request for heating and to an increase in the demand for electricity for cooling especially in the southern Europe, where high carbon intensity coefficients cause large CO2 emissions. The resulting vicious circle can be interrupted by increasing the energy efficiency of buildings and properly converting thermoelectric power plants. Results also show that in the future the Mediterranean basin will suffer more than other European areas for phenomena linked to global warming.

The European Union is working on strategies in order to increase the energy efficiency of buildings. A useful solution is to identify the energy performance of buildings through the Energy Performance Certificate (EPC), as it provides information for the comparison of buildings with different architectural typology, shape, design technology and geographic location. However, this tool does not assess the real energy consumption of the building and does not always take into account its impact on the environment. In this work, two different types of analysis were carried out: one based only on the energy efficiency and the other one based on the environmental impact. Those analyses were applied on a standard building, set in three different Italian locations, with the purpose of obtaining cross-related information. After the evaluation of the results, interventions on some parameters (walls insulation, windows frame, filler gas in the insulated glazing) have been identified in order to improve the energy behavior of the building with an acceptable environmental impact. The aim of this paper is to propose a methodology that integrates the EPC with green building rating systems, leading to a more conscious choice of retrofit interventions as a compromise between energy performances and environmental impact.

Outdoor thermal comfort affects the health of the people and the quality of life in urban areas. This is the reason why in the past few years different mitigation strategies for the microclimate have been studied and examined. These strategies depend on those passive factors characterizing the urban setting that are able to affect the values of local meteorological variables, as the limit surfaces of the urban space (parterre and façades of the buildings). This paper examines the Cloister by Giuliano da Sangallo, which is part of the Faculty of Engineering of Sapienza University of Rome. The case study compares the present configuration of the Cloister with four other configurations characterized by some vegetation and materials with a high albedo by taking into consideration the PMV (Predicted Mean Vote) model. Microclimatic variables are calculated through numerical simulations performed by the ENVI-met software. Such a comparison is performed during a typical summer day. While examining the results it can be noticed how the strategy presenting the best results is the one with some vegetation, whereas the materials with a high albedo improve the microclimate if applied on surfaces characterized by a high sky view factor.