1,720,992 research outputs found
Good places to live and sleep well: A literature review about the role of architecture in determining non‐visual effects of light
No full text: Light plays a crucial role in affecting the melatonin secretion process, and consequently the sleep-wake cycle. Research has demonstrated that the main characteristics of lighting affecting the so-called circadian rhythms are spectrum, light levels, spatial pattern and temporal pattern (i.e., duration of exposure, timing and previous exposure history). Considering that today people spend most of their time in indoor environments, the light dose they receive strictly depends on the characteristics of the spaces where they live: location and orientation of the building, dimensions of the windows, presence of external obstructions, geometric characteristics of the space, optical properties of walls and furniture. Understanding the interaction mechanism between light and architecture is fundamental to design non-visually comfortable spaces. The goal of the paper is to deepen this complex issue. It is divided into two parts: a brief historical excursus about the relationship between lighting practice and architecture throughout the centuries and a review of the available research works about the topic. The analysis demonstrates that despite the efforts of the research, numerous open questions still remain, and they are mostly due to the lack of a shared and clear method to evaluate the effects of lighting on circadian rhythm regulation
Simplified modelling methods to design integrative lighting
No full textEvaluating non-visual effects of light is crucial. Designers often use DIALux for this purpose even if it is intended for calculating photopic quantities exclusively. To verify its applicability in this context, two approaches for melanopic equivalent daylight illuminance calculation are compared against measured data. Measurements were performed for 21 scenarios obtained combining 7 wall colours and 3 CCTs. Method 1 adopts traditional DIALux simulations, in method 2 melanopic flux and reflectance replace the corresponding photopic quantities. Method 2 performs better in 71.43% of cases, especially for colours highly reflective in long wavelengths; the opposite occurs for colours most reflective in short wavelengths
Office workers’ performance and satisfaction with the luminous environment under standard and daylight mimicking LEDs
No full textThe effects of illuminance and correlated colour temperature (CCT) on people's work performance, mood, and comfort have been previously investigated, but some aspects need to be deepened. In particular, CCT does not uniquely describe light spectral power distribution (SPD), hence it is not sufficient to define the effects of light on people's non-visual responses. This study aims to extend current knowledge about the acute effects of light on people's work performance, mood, and environmental appraisal by carrying out a 2x2 mixed design experiment where LEDs' SPD (standard and daylight-mimicking) is the within-subject factor and CCT (4000 K and 6500 K) is the between-subject factor. 40 participants, aged between 18 and 35, joined the experiment. It was found that SPD has significant effects on reaction time in selective attention and errors in working memory activities, being the performances under daylight-mimicking LEDs the best. Moreover, a lower number of errors in sustained attention and executive function was registered under 4000 K against 6500 K, but better performances occurred under 6500 K against 4000 K considering errors in selective attention and reaction speed in sustained attention. Regarding room appraisal, 4000 K was preferred over 6500 K and daylight-mimicking LEDs were preferred over the standard ones
Lighting Quality Self-assessment in Italian Home Offices
No full textThe spread of information technology and the improvement of telecommunicating systems have changed the way to conceive work. People performing typical office activities provided with a laptop and an internet connection can work in whatever place: a coffee house, a waiting room of a train station, an airport, or their own home. The habit to work at home has amazingly spread due to the Covid-19 pandemic, arising crucial questions. Are home work-stations comfortable enough to work? Are lighting conditions of residential spaces proper to perform typical office activities? This paper presents a survey investigating the typical characteristics of the luminous environment in home working spaces (considering both daylight and electric light) and people’s average awareness about light and lighting-connected themes. The research has been carried out through an online questionnaire addressed to home workers and students forced to stay home because of the Covid-19 spread. The results demonstrated that many interviewees have difficulties in managing light and are not completely aware of the right actions to take to improve lighting quality of home workplaces. Moreover, a complete lack of knowledge about electric light has emerged. So, popularizing more knowledge about light and lighting-connected themes is prominent. Indeed, now and even more in the future, people will work in places other than the traditional workplaces, for which standards regulating lighting characteristics do not exist. In this context, the definition of ad hoc guidelines and the spread of best practices should be a crucial goal for researchers and experts in lighting
Testing the use of daylight-linked control systems to address integrative lighting and energy savings in office buildings
No full textDaylight-linked control systems (DLCSs) are used to maintain constant work plane illuminance and save energy. If properly calibrated, they could be used to guarantee circadian requirements fulfilment as well. In this study, the functioning of a closed-loop proportional dimming system is simulated based on on-field measurements. Simulations are performed calibrating the system to achieve different targets: three work plane task illuminances (300 lx, 500 lx, 750 lx) and one melanopic equivalent daylight illuminance (melEDI) value (250 lx) alternatively. Four electric light CCT profiles (stable at 3000 K, 4000 K, and 6500 K, and variable during the day) are considered. Results demonstrate that when the system is calibrated according to work plane illuminance, melEDI values are always fulfilled under clear sky and with overcast sky when task illuminance and CCT are high. When the system is calibrated to meet circadian requirements, the CCT choice is crucial to guarantee work plane illuminance
Una nuova metodologia per definire le prestazioni dei sistemi di controllo automatico per l'illuminazione gestiti da fotosensori
No full textÈ 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
Optical characteristics of traditional portuguese azulejos: Mixing colors to obtain “Cool” building façades
No full textEffects of light source spectrum and background colour on the perception of paintings
No full textThis paper presents an experiment on the effect of light on the perception of paintings. The experiment was performed in a test-room where a typical museum exhibition set-up was simulated. Two different paintings were shown to 44 participants, under different light scenes obtained by using tuneable LED (Light Emitting Diode) wallwashers. To set the light scenes, the following parameters were modified: correlated colour temperature of the lighting, illuminance on the painting and the colour of the background wall. Participants answered a questionnaire to assess the perception of the paintings’ colours, the lighting conditions and the pleasantness of the exhibition set-up. The results demonstrated that illuminance is the parameter mainly affecting perception, for both paintings. However, correlated colour temperature and wall colour, as well as the combination of the three different considered parameters, can more or less influence perception depending on the chromatic composition of the painting
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