• Energy Research

Abstract The goal of this analysis has been the search for the optimal configuration for a finned plate (with rectangular and vertical fins) to be cooled in natural convection. Utilizing a simplified relation of the fins heat exchange some simple expressions for the determination of the optimum value of the fins spacing have been developed as a function of the parameters which feature in the configuration: dimensions, thermal conductivity, fins absorption coefficient and fluid thermo-physical properties.

The goal set by the EU of quasi-zero energy buildings is not easy to reach for a country like Italy, as it holds a wide number of UNESCO sites and most of them are entire historical old towns. This paper focuses on the problem of the improvement of energy performance of historical Italian architecture through simple interventions that respect the building without changing its shape and structure. The work starts from an energy analysis of a building located in the historic center of Tivoli, a town close to Rome. The analysis follows the recommendations of the UNI TS 11300-Part1, which indicates how to evaluate the energy consumptions. The calculations were performed only on the building envelope, based on passive solutions and alternatives. Four passive strategies were examined and applied based on the location of the building and the non-alteration of the structure and the landscape. The obtained results impacted positively on the energy performance of the building: the annual energy saving reached a maximum value of 25%. This work shows how it is possible to improve the energy performance of an existing building achieving a significant energy saving with the respect of the building architecture, shape, function and the surrounding landscape.

Stimulation elicited by a real world field of view is related to the color, the intensity and the direction of the information reaching the eye: different spectral power distributions of light trigger different responses. An evaluation of the stimulation provided by the field of view can be performed by measuring the spectral radiance with a spectroradiometer and weighting this data with an efficiency curve. Different weights (physical, physiological and psychological) can lead to different analyses and consequently to different results. The proposed method allows an overall and simplified evaluation of the field of view based on spectral and luminance measures and a script that processes the luminous information. The final aim of this approach is to provide further information about the light stimulation reaching the retina and to supply a qualitative evaluation of the field of view, allowing to know how much stimulation is coming from a certain area within the visual field depending on the type of surface, basing on spectral and directional information. This approach can have practical implications, allowing technicians and designers to take into consideration the possible visual fields, in order to properly shape the features of stimulation throughout the day, hence following a field of view-based dynamic design.

A road tunnel is an enclosed and covered infrastructure for the vehicular traffic. Its lighting system provides 24 h of artificial sources only, with a higher amount of electric power used during the day. Due to safety reasons, when there is natural lighting outside the tunnel, the lighting levels in the stretches right after the entrance and before the exit must be high, in order to guide the driver’s eye towards the middle of the tunnel where the luminance must guarantee safe driving, avoid any over-dimensioning of the lighting systems, and produce energy savings. Such effects can be reached not only through the technological advances in the field of artificial lighting sources with high luminous efficiency, but also through new materials for road paving characterized by a higher reflection coefficient than other ordinary asphalts. This case study examines different technical scenarios, analyzing and comparing possible energy and economic savings. Traditional solutions are thus compared with scenarios suggesting the solutions previously mentioned. Special asphalts are interesting from an economic point of view, whereas the high costs of LED sources nowadays represent an obstacle for their implementation.

Proper lighting is vital to improve, from an artistic point of view, the surface expanse and decorative detailing of architectural heritage buildings considered valuable. When properly lit, monumental buildings can become to onlookers an essential part of the city. Nowadays, for design planners dealing with the improvement of buildings, whose architectural design should be valorized, the real challenge is to combine the lighting artistic requirements with scrupulous economic management in order to limit the energy demand and to respect the environment. For these reasons, this case study examines the lighting of the monumental façade and the cloister of St. Peter in Chains situated in the Faculty of Engineering of Sapienza University of Rome. The present lighting installation, characterized by metal halides, compact fluorescent and halogen lamps, is compared with an alternative scenario presenting LED lamps and scenographic lighting of the monumental façade. Such comparison is based on the evaluation of the lighting levels for different visual tasks and on energy and maintenance issues; the first analysis was performed through the software DIALux Evo 4.0, whereas the second was performed using ecoCALC. This study leads to the conclusion that the lighting levels of the solution presenting LED lamps are better than those of the present solution, and they comply with current standards. Finally, the higher costs of LED lamp installations and the scenographic lighting of the monumental façade are balanced by lower maintenance costs, with a payback period of seven years.

University campuses can be developed and improved through the application of the Smart concept. Previous researches have proposed a Smart Campus model based on incidence matrices in order to choice suitable integrated strategies. This methodological framework has been applied on the headquarter of Sapienza, University of Rome. The winner strategy resulting from the Environmental evaluation has been numerically simulated and the results have shown their impacts in terms of energy, environmental and economic perspectives.

Abstract Nowadays companies supplying medium/high voltage electric energy, near residential areas, tend to use underground cables laying. Hence the design engineer is required to estimate the thermal resistance around the underground cable to perform a right dimensioning of the cables; as a matter of fact what it should be avoided is the overheating determined by a bad heat dissipation due to the Joule effect. IEC rules provides a formula for the evaluation of the soil thermal resistance which is easy to apply. But from an experimental point of view, as the bibliography shows, it was discovered it tends to underestimate the problem when dealing with very dry soils in particular. Thanks to an experimental system, some useful data were collected for the validation of a 2D FEM model of an excavated area with a linear heat source reproducing the underground conduit. The numerical model presents a variation of both the geometrical parameters of the excavated area and the distance characterizing other cables (hence heat sources) located in the same site of installation examined. In this way two dimensionless coefficients, useful to correct the values of the thermal resistance furnished by the current regulations, were determined.