• Energy Research

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.

Indoor Environmental Quality (IEQ) is a crucial issue in school buildings, because of the conditions that pupils and students are exposed to. From this assumption, potentialities of retrofit actions with Nearly Zero-Energy Building (NZEB) targets were analyzed in existing school buildings, focusing on the impact of such measures of IEQ. Numerical analyses in a transient regime for a typical school building were carried out to assess the impacts on the thermal comfort and Indoor Air Quality (IAQ). The study took into account several building configurations and three reference cities. The results showed severe overheating risks in retrofitted schools: the operative temperature increased by several degrees with respect to the existing configuration, leading to thermal discomfort for a relevant part of the observation period. Passive techniques, namely external solar protection devices and night ventilative cooling, were applied to assess their mitigation potential. Results showed that the combination of the two solutions restored the pre-retrofit performance. CO2 levels were found to be too high for naturally ventilated buildings, regardless of the building configuration; acceptable levels might be reached only with long opening times of windows, which are unrealistic for real building operation.

Abstract Energy retrofit projects following nearly zero-energy buildings (nZEB) requirements often pay a little attention to Indoor Environmental Quality of the building. This aspect is extremely important in school buildings, as they are frequented mostly by young people, who are affected more by a healthy environment. In this context, starting from a reference case, overheating risks in existing school buildings considered for energy renovation were investigated through TRNSYS 16. Four building configurations were evaluated (existing, nZEB, nZEB with external shadings, nZEB with external shadings and night ventilation) and the influence of several parameters was taken into account (climate, orientation, building level). The aim of this paper is to understand if nZEB standards applied to Italian school buildings guarantee good indoor thermal conditions and which building configuration can be more advantaged by these standards. Furthermore, even if overheating risk is qualitatively recognized in insulated and air tight buildings, quantitative assessments are still missing for the Italian building stock. The intent of this research is to provide preliminary data on this topic in order to lead to a more conscious choice of retrofit strategies as a compromise between energy performances and indoor environmental quality.

The periodic stabilized regime is the condition where the temperature of each point of a certain environment varies following a periodic law. This phenomenon occurs in many practical applications, such as passive or ancient buildings not equipped with Heating, Ventilating and Air Conditioning HVAC systems and located in latitudes where the temperature greatly varies with Earth’s daily cycles. Despite that, the study of transient phenomena is often simplified, i.e., considering negligible the thermal response of the indoor microclimate. An exact solution to enclosures whose microclimate is free to evolve under a periodic stabilized regime does not exist nowadays, also from an analytical point of view. The aim of this study is to parametrically analyze the thermal variations inside a room when a transient periodic temperature is applied on one side. The phenomenon has been numerically studied through Computational Fluid Dynamics (CFD) and analytically validated using a function that reproduces the daily variation of the outdoor temperature. The results of this research would lay the groundwork to develop analytical correlations to solve and predict the thermal behavior of environments subject to a periodic stabilized regime.