• Energy Research

Tunnel lighting installations function 24 h a day, 365 days a year. These infrastructures have increased exponentially and now connect quite distant locations, even on different continents. This has led European administrations and international regulatory bodies to establish regulations for tunnel safety with the lowest environmental impact. However, until now, these regulations have almost exclusively focused on traffic safety, and relegated sustainability to the background. Even though they recognize the need to reduce energy consumption, they do not propose any tools for doing so. Given the impact of these installations and the lack of a specific regulatory framework, Asian countries will soon be forced either to update previous standards for tunnel lighting or elaborate new ones. A better understanding of the weaknesses of European regulations combined with a willingness to embrace innovation could position Asia as a world leader in the regulation of more sustainable road tunnels. The objective of this research was to improve the sustainability of tunnel lighting installations through new regulations or amendments to existing ones, without impairing the mental well-being of users, who could potentially be affected by energy-saving measures. Accordingly, this paper presents and analyzes a broad proposal for formulating tunnel lighting regulations. The originality of this proposal lies in the fact that it integrates road safety, lower environmental impact, and user well-being. Furthermore, it is expected to broaden the perspective of regulatory bodies and public administrations with regard to tunnel installations, which would ultimately enhance their sustainability.

Although actions promoting sustainable energy production and consumption have been widely approached in the literature, the management of the big scientific projects devoted to these actions have not been considered as a matter of study from the perspective of sustainable development, but almost exclusively from the scientific or technical ones. Experiences all over the world are increasingly demonstrating that the impact of the project phase is more critical than expected. In this sense, the joint international research on clean and more efficient nuclear power, especially fusion, is currently focused on two large projects: ITER and IFMIF-DONES. Although ITER is step by step advancing, IFMIF-DONES still has a long way before it is actually implemented and its main target (the evaluation of the materials to build the future nuclear fusion reactors) is achieved. In this work, the different steps focused on IFMIF-DONES funding and management planning up to date are analysed and, departing from them, some key points on the future development of the project are proposed.

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.

Highlights? The problem of uniformity and installation efficiency in public lighting is optimized. ? The most accurate values of height and spacing have been determined with NSGA-II. ? The results have been successfully compared with a well-known and reliable free software. This paper presents a new method for calculating the design of roadway lighting. Apart from its accuracy, this method, which is based on a multi-objective evolutionary algorithm, has the added advantage of enhancing the energy efficiency of lighting installations. This is positive because the economic use of energy resources is evidently a priority in the world today. In our study, an exhaustive calibration process was used to fine-tune the accuracy and precision of the new method presented. The results obtained were then compared with those of DIALUX, a well-known free software program that is frequently used for the design of lighting installations. In the second phase of this research, the lighting installation was made more complex in order to verify the applicability of this new method to a wide range of different contexts.

The presence of walls with different reflectance in indoor facilities is a problem when designing their lighting installations. This problem becomes more serious when one or more walls are mirrors, a common situation in medical, sport, educative and many other indoor facilities. Even if some programs can work with different approaches, the results are far from exact and, in many cases, designers ignore the mirrors and work by eye, with results that are frequently excessive in terms of illuminance on the working planes, glare and energy consumption and use of materials. These deviations from the intended results are due to the direct or indirect estimation of reflectance remarkably lower than 1 in the mirrored walls. In this framework of uncertainty, this work is presented with the objective of developing an intuitive theoretical model based on the consideration of virtual twin-spaces behind the mirrors. This proposal is not just an approach, but a useful tool providing the input for any kind of calculation ranging from the lumen method, used in quick pre-dimensioning, to the most complete calculations with computational methods. In addition, apart from calculating the number of luminaires and photometric parameters, the use of virtual twin-rooms also takes into account the extended field of vision of the users, including objects behind, and virtual luminaries. This advantage has no precedent in the literature up to date.

In this study, new relationships between the energy efficiency of street lighting systems, street width, and luminaire height were derived from the analysis of a large sample of outputs, generated with a software application widely used for lighting design. The result was a quadratic polynomial that perfectly fit the relationships obtained and whose coefficients characterize each type of luminaire. This greatly simplifies the design of lighting facilities because it only uses one equation, but at the same time, takes all necessary variables into account. The procedure maximized the energy efficiency of the street lighting systems, as far as conditions allowed, and greatly facilitated the calculation of the parameters of a basic lighting installation, according to CIE (International Commission on Illumination) recommendations.

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.