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È opinione comune che l’utilizzo di sistemi di controllo automatico per l’illuminazione gestiti da fotosensori consente di ottenere notevoli benefici sia in termini di risparmio energetico, che di miglioramento del comfort degli utenti. In realtà, ad oggi, le conoscenze sul reale funzionamento di tali sistemi sono piuttosto confuse e la letteratura scientifica riporta risultati talvolta contrastanti riguardo sia i risparmi energetici conseguibili, sia il grado di accettazione da parte degli utenti di un controllo di tipo automatico. Ciò dipende dal fatto che le prestazioni di tali sistemi sono fortemente influenzate da molti fattori, primo fra tutti la disponibilità di luce naturale; quindi la stessa soluzione tecnica, valida per un caso specifico, se applicata in un altro contesto può fornire risultati molto differenti. Dato il loro comportamento dinamico, uno dei problemi fondamentali della progettazione di tali sistemi è proprio la difficoltà nel descriverne le prestazioni tramite degli indici sintetici che siano in grado di consentire di volta in volta il confronto veloce ed immediato tra strategie progettuali differenti e l’identificazione della soluzione tecnica più adeguata al caso specifico. Date queste premesse, il lavoro descrive una nuova metodologia per definire le prestazioni dei sistemi di controllo automatico per l’illuminazione gestiti da fotosensori, basata sull’utilizzo di nuovi parametri prestazionali e presenta l’applicazione di tale metodo ad un caso studio, al fine di dimostrarne l’utilità.

The paper reports a case study regarding a retrofit intervention realized in a factory located in Nola, Naples (Italy). The intervention consists in the substitution of old luminaires with LED and in the installation of a smart and open control system. The goal of the customer was, on one hand to increase the efficiency of lighting system, in order to reduce energy consumptions and, on the other hand, to improve luminous environment quality to guarantee appropriate comfort conditions to workers. Furthermore considering system's dimensions and its characteristics it was necessary to simplify maintenance activities.

It is by now accepted that light has significant effects on people well-being in terms of both visual and non-visual comfort. According to the Hue Heat Hypothesis, Correlated Colour Temperature can affect people thermal perception: a cool light would determine a cool sensation and a warm light a warmth sensation. Despite several studies investigated this issue, published results are conflicting. The paper shows outcomes of laboratory surveys that are in good agreement with the HHH. Moreover, it presents results of dynamic daylight simulations aiming at studying the way design strategies, implementing the HHH, modify indoor luminous environment and energy consumptions due to lighting.

Daylighting is a strategic topic to achieve sustainable buildings, so it is more and more imperative that it is implemented in architecture curricula to prepare a new generation of daylighting-oriented practitioners. In this frame, the DAYKE project (Daylight Knowledge in Europe) was set up to explore the level of knowledge about daylighting among European professionals and students. DAYKE-Europe was replicated as DAYKE-Italy to study the knowledge of daylight standards, metrics and software among Italian architecture students, and to compare it to that observed within DAYKE-Europe. A sample of 542 questionnaires were collected in five universities. Primary outcomes were: (i) a general low level of knowledge on daylighting was observed; the most cited metrics were the average daylight factor and the geometrical window-to-floor ratio, while climate-based daylight metrics were rarely mentioned; (ii) master science M.Sc. students reported more knowledge on daylight metrics and regulations than bachelor B.Sc. students, while the implementation of daylight metrics and strategies in projects was mainly deficient among B.Sc. students; (iii) compared to European students (DAYKE-Europe), Italian students showed a higher knowledge of daylight metrics and software (especially as for M.Sc. students), while the opposite was observed for standards, regulations and protocols. Based on the results, a reconsideration of daylight education in architecture curricula is recommended.

Results from the DAYKE-Italy project are presented. An investigation on daylighting in eight classrooms in five Italian universities was carried out through a combined approach: an ad-hoc survey administered to students to investigate how they perceive daylight in classroom, and numerical simulations (DIVA + ALFA) to calculate a set of objective metrics (daylight, circadian, and energy-related). A sample of 542 questionnaires was collected through two sessions and the subjective judgments were correlated to objective metrics. Results from descriptive and statistical analyses showed: (i) the correlation was significant for all daylight metrics: among them, average daylight factor and annual light exposure performed higher correlations compared to daylight autonomy, spatial daylight autonomy and useful daylight illuminance; (ii) rooms with a scarce or an optimal daylight provision (according to standards) were rated with comparable subjective score; (iii) the equivalent melanopic lux showed a higher correlation than daylight metrics based on the horizontal workplane; (iv) energy saving up to 50% can be achieved in the presence of high daylight provision and through daylight responsive controls; however, a relamping of fluorescent systems with LED system is recommended to optimize the consumption; furthermore, estimated saving correlated significantly with objective metrics.

The application of “shiftable” or “modulable” load (i.e. washing machine, dishwasher, etc.) in a Smart Grid, can provide energy saving or modify the power flows in the grid, allowing a reduction of the electrical power peak. This paper explores the possibility to modulate the indoor artificial lighting to support this reduction. The study examines the impact of two different measures of power shaving. On the one hand, the change of Correlated Colour Temperature of the light source, and, on the other hand, the dimming of its luminous flux. The possibility to merge the above-mentioned technical solutions is also analyzed. Based on these strategies, several daily schedules of lighting management are defined, and the corresponding energy saving during some critical time slots are assessed. Results show that in all cases, it is possible to achieve a significant reduction of the absorbed power and a consequent increment of energy savings (up to 59%) also in specific time ranges. Furthermore, considering the application of a Daylight-linked control system, it was observed that power regulation associated with the exploitation of the daylight represents itself a way to dynamically reduce the electric loads on the grid.

This paper proposes a study about the feasibility to modulate the indoor artificial lighting, taking into account both achievable energy savings and comfort conditions, in order to reduce lighting electric loads. In particular, it focuses on the possibility, on one hand, to decrease the luminous flux and, on the other hand, to change the Correlated Colour Temperature (CCT), in order to decrease the absorbed power. Moreover, the impact of daylight-linked control systems was considered. Finally, the possibility to combine the different technical solutions was analysed. The paper proposes the definition of daily scheduling referred to lighting energy management, in order to modulate the maximum load value, maintaining a minimum during the rest of the time for an office end use.

Nowadays, there is an in-depth debate about the suitability of daylight saving time. The shift of one hour during summer time allows a better use of daylighting reducing energy consumptions. However, the impact of daylight saving time on the human health has not been quantified in most of the scenarios. The aim of this study is to determine the impact of daylight saving time on the health of occupants (by calculating Circadian Stimulus Autonomy) and on the energy consumptions for lighting (by calculating Daylight Autonomy) in office buildings. A standard office is analyzed in eleven representative locations of Europe and for three different time schedules: with daylight saving time, with continuous winter time and with continuous summer time. Despite restricted to a specific case study, results provide elements useful to evaluate pros and cons in maintaining daylight saving time, confirming that they are strongly dependent on the geographical position and on the local luminous climate. It was demonstrated that, abolishing daylight saving time, maintaining the local time all the year (winter time), would determine a reduction of Daylight Autonomy generally lower than 6% and that this decrease would be more consistent for cities characterized by higher latitude. At the same time an increase of Circadian Stimulus Autonomy values would be obtained, more consistent for northern cities (maximum observed increment 16%). On the other hand, applying the one-hour shift for the entire year (summer time) would not determine benefits in terms of energy savings nor of impact on circadian system.

The goal of the paper is to analyse the daylighting design criteria in ancient Roman domus, by using as case study a famous ancient Roman building: the villa of the Mysteries in Pompeii. At this purpose the work is divided in two sections: a typological analysis of the roman houses, aiming at understanding the link between the ancient building criteria and the daylight harvesting ones; a dynamic simulation of the daylight conditions inside the Villa of the Mysteries. In this regard, to assess the indoor daylight availability an ad-hoc methodology, based on the proposal of a new set of performance metrics (the Characteristic Daylight Illuminance -CDI-; the minimum CDI - CDImin-; the spatial CDI -sCDI-) is introduced in order to process simulation results. Results demonstrate that in the past there was a strong correlation between building criteria and daylighting ones: the choices about the dimensions of the windows and the use of static shading systems (porches and peristyles) were wise and reasoned. Moreover, there was a correspondence between daylighting criteria and the functions of the spaces: the more prestigious a room was, the more daylight entrance was permitted. Daylight levels were generally higher in representative spaces like atria, triclinia and tablina, with CDImin values generally comprised between 200 lx and 500 lx, and lower in cubicula and service/working spaces, with CDImin values generally comprised between 0 lx and 100 lx. The obtained results can be useful to design the modern electric lighting system in the villa. Moreover, the proposed analysis methodology can be easily exported to other applications (both ancient and modern buildings). Further studies should apply the same methodology to other case studies to verify if the outcomes of the research are generalizable. Fil: Monteoliva, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ambiente, Hábitat y Energía; Argentina Fil: Bellia, Laura. Università degli Studi di Napoli Federico II; Italia Fil: Fragliasso, Francesca. Università degli Studi di Napoli Federico II; Italia Fil: Pattini, Andrea Elvira. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ambiente, Hábitat y Energía; Argentina

The achievement of a good visual environment is key to guaranteeing human satisfaction indoors. In this context, it is crucial to assess the visual environment through the measurement of human perception. However, the assessment of the visual environment through human perception is often complicated. Using real spaces or mock-ups is time consuming, costly, and does not allow the control of all possible variables (e.g., daylight). Photorealistic rendered images present several limitations, starting from the veracity of the visual stimulus presented to participants. Virtual Reality (VR) is emerging as a valid alternative for evaluating the perception of the indoor visual environment due to the ability to control selected variables, analyse cause-effect relationships, and save time and cost, especially for the evaluation of daylit spaces. The high level of immersion and the possibility of interaction provide an opportunity to study users' perceptions and behaviors. However, some aspects of light assessment in VR need further investigations, such as the comparability of the perception of light in real and virtual environments. This paper reviews the available literature on the topic, highlighting the advantages and disadvantages related to the use of VR for lighting research and design. Previous research is classified into 1) studies focused on the comparability between lighting conditions in VR and real environments; 2) studies about users’ perception and behavior with respect to lighting scenarios in VR; and 3) studies exploiting VR for lighting design. Hardware and software used in existing literature are further analyzed. This paper highlights that more studies are needed to define a common investigation protocol to make VR a valid investigation tool for lighting research studies aimed at evaluating visual quality and lighting perception.

A sustainable building design should be compliant with the even more pressing en-ergy saving requirements - as in NZEB - and high levels of Indoor Environmental Quali-ty. In this context, despite it is accepted that different facets of IEQ could have antago-nistic effects on building energy demand, relatively few studies are aimed at investigat-ing the mutual interaction among its four components (thermal, acoustic, visual and in-door air quality). From this point of view, the hue-heat hypothesis is based on the idea that light and colours can affect the thermal perception. Particularly, spectral power dis-tributions of light shifted to short wavelengths seem to promote a cooler thermal percep-tion and the vice-versa. To verify this hypothesis, the object of this paper is the analysis of preliminary results obtained by a subjective investigation carried out in a special me-chanically conditioned test room provided with white-tuning LED sources. The first sample of subjects has been exposed to two different lighting scenarios characterized by warm (3000 K) and cool lights (6000 K) at a fixed illuminance value (300 lx) at the task area and typical winter thermohygrometric conditions. Preliminary results seem to con-firm that cooler light induces a shift of the thermal sensation toward cold. The percent-age of people under warm conditions decreased from 24 to 6% with an increase of sub-jects under thermal neutrality conditions from 32 to 49% (from 32 to 55% for females) in case of cold light.

Evaluating indoor daylight availability is extremely important in order to define the characteristics of an environment in terms of visual comfort and energy performances of lighting systems. The criticism of the static calculation approach based on Daylight Factor led to the development of the Climate Based Daylight Modeling (CBDM) one. Dynamic simulations are performed thanks to the use of specific software and the choice of a calculation tool or another could provide different output results. Therefore the aim of this paper is to compare results of dynamic daylight simulations carried out with two different software, Daysim and 3ds Max Design® and referred to a simple office located in 4 different cities and exposed according to the 4 main orientations. It demonstrates that differences in results are more or less significant depending on several factors: outdoor daylight conditions, window’s orientation and considered internal calculation point.

This paper is the second step of a research project aimed at investigating the impact of the use of different weather data files on daylight simulations’ results. Simulations were carried out for a simple standalone office using three weather files (IWEC, Meteonorm and Satel-Light) for two European locations (Copenhagen and Rome); moreover the office’s exposure was changed according to the four main orientations (North, East, South and West). Results were analyzed both in terms of Annual and Monthly Light Exposures, dynamic daylight performance metrics (DA, DAcon, UDI) and sunlight’s incidence. It was demonstrated that differences between the results obtained with the different weather files are more significant considering Annual and Monthly Light Exposures (highest value 20%), whereas they decrease when analyzing illuminances with a statistical approach (DA, DAcon, UDI). The analysis of sunlight’s incidence also determined similar results using the three weather data files and the maximum difference is 5% independently from the orientation.

This paper reports the results of measurements performed in a test room to investigate the impact of using different wall colours and light scenes on indoor lighting quality. Eye level spectral irradiances were measured for a user located inside the room and seated at a desk. These measurements allow the use of the Irradiance Toolbox, which makes it possible to calculate equivalent illuminances for the photopigments in the human eye. Moreover, the CIECAM02 colour appearance model was used to investigate the variations in hue and chroma values of the different wall colours when changing the light scene. The results demonstrate that there are significant variations in eye level spectral irradiance distributions, photoreceptor stimulation and hue and chroma values with different combinations of wall colours and light scenes.

Colours perception depends on many factors, some attributable to sources used to light the observed objects and others to the optical properties of the objects themselves and of the space they are located in. Moreover, it cannot be neglected that, as for all visual phenomena, colour perception is also influenced by observer’s psychological and physiological conditions. Although the enhancement of colours perception is central in all lighting designs, it obviously becomes crucial in cultural heritage applications. In these cases, it is fundamental to define a proper balance between the necessity to highlight chromatic coordinates of lit artworks and to protect them by the light-connected damages, fulfilling prescriptions about maximum exposure levels [1]. The complexity of lighting design is greater when artworks are not located in museums or exhibition rooms, but are positioned in their original place and the entire architectural space must be considered a piece of art, e.g. churches or archaeological ruins. In these cases, design problems are greater: the location of luminaires is difficult because their installation must not adulterate the integrity of the cultural good; moreover, often it is not possible to access to all architectural spaces and consequently it must be considered that the artwork to lit (e.g. a fresco or a mosaic) will be observed from a specific distance and that its details will not be entirely appreciated by the observers. In order to account all these aspects, when lighting design deals with cultural heritage the preliminary analyses are crucial. Given these premises, the goal of this paper is to present a methodology useful to scientifically characterize artworks colours and to provide a valuable tool to choose the most suitable electric artificial sources in order to highlight their chromatic properties. This methodology was used during the preliminary studies to define the lighting system for some of the most famous ancient roman frescoes: the frescoes of the triclinium of the villa of the Mysteries in Pompeii. Specifically, the analysis focused on the wall in front of the entrance of the triclinium. It was divided in two parts: the analysis of the current lighting conditions and the chromatic analysis of fresco colours. Daylight irradiance measurements and luminance maps were obtained to characterize the luminous environment. Then dynamic daylight simulations were performed to identify the recurring daylighting conditions inside the triclinium. The fresco was divided in several chromatic areas based on its predominant colours. Each area was characterized by means of spectral reflectance factors measurements and the chromatic coordinates of the measured samples were identified and compared.