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Evaluating Lighting Equipment
Published in Craig DiLouie, Lighting Redesign for Existing Buildings, 2020
Like conventional sources, LED devices have a declining rate of lumen depreciation over their life. In fact, being an electronic device means that failure modes are quite different from standard lamps, which burn out long before their decline in light output becomes a significant issue. LEDs may last as long as 100,000 hours before failure, but at some point the amount of light being produced is so low that replacement is necessary to restore light levels. Because of this, service life of an LED product is rated at the time in hours of operation where the product is producing 70 percent lumen maintenance (30 percent loss of light output, about 15,000-50,000 hours for an LED device depending on whether the LEDs are overdriven and by how much) for general lighting applications and 50 percent lumen maintenance for decorative and other non-critical applications (up to 50,000-70,000 hours in well-designed products is possible).
Lighting
Published in Dorin O. Neacşu, Automotive Power Systems, 2020
The color temperature is measured in temperature degrees of Kelvin (symbol: K) on a scale from 1,000 K to 10,000 K. For commercial and residential lighting applications, Kelvin temperatures fall somewhere on a scale from 2,000 K to 6,500 K. For a color temperature under 3,000 K, colors are called “warm” and look yellowish. This is simply known as “warm light.” A light source with a color temperature of around 3,000 to 3,500 K appears less yellow and more whiteish. Above 5,000 K, the light produced appears bluish-white (sometimes improperly called xenon). This is simply known as “cool light.” Finally, it is noteworthy that the color temperature of daylight varies, but is often in the 5,000 K to 7,000 K range.
Red Light At Night To Enhance Cognitive Functioning For Society’S Special Needs Groups
Published in Manuel Couceiro da Costa, Filipa Roseta, Joana Pestana Lages, Susana Couceiro da Costa, Architectural Research Addressing Societal Challenges, 2017
E.V. Ellis, D.L. McEachron, E.W. Gonzalez, D.A. Kratzer
The dLUX light lab at Drexel University has developed an LED lighting system that auto-tunes natural daylighting in its full diurnal changing color spectrum and light intensity during the day and changes to dim red lighting during the nighttime hours. This 24/7 LED luminaire mimics the full spectrum of natural daylight in both color temperature and light intensity. Through a combination of white and RGB (red, green, blue) LEDs the lighting system is programmed to change color throughout the day to mimic the full spectrum of natural daylight from dawn to dusk; to change in color from the amber rising sun to the red setting sun and to illuminate the indoor environment with a low-intensity red light throughout the nighttime hours.
A proposal on residential lighting design considering visual requirements, circadian factors and energy performance of lighting
Published in Journal of Asian Architecture and Building Engineering, 2023
The reference building energy model was generated in the Designbuilder software and the annual energy performance simulations were run in the EnergyPlus engine in accordance with the architectural project and Building Energy Performance National Calculation Methodology (BEP-TR) results. The window-to-wall (WWR) ratio of the building is 27%. The total solar heat gain coefficient (SHGC) is 0.75 and the visible light transmittance of windows (Tvis) is 0.80. The reference building’s occupancy data is based on a previous survey (Manav and Kaymaz 2021) and the lighting power densities are specified according to the selected luminaires in the lighting scenario, as defined in Section 2.1. In the lighting energy analysis, occupancy-based lighting schedules, daylight-linked lighting control and the light reflectance value (LRV) of walls are evaluated. The average lighting energy use per square meter is compared with the reference buildings for the following scenarios.
Methodology for visual comfort analysis in intermediate open spaces of residential areas, case study: Nagpur, India
Published in Architectural Engineering and Design Management, 2022
Concerning users’ comfort, heat and light are among the physical environment’s predominant factors in a housing design. In response to these factors, the primary function of the built environment is to provide its users with thermal and visual comfort (Chokhachian, Santucci, & Auer, 2017). However, a brief literature review shows that visual comfort in intermediate open spaces is seldom studied. Visual comfort is ‘a subjective condition of visual well-being induced by the visual environment.’ The availability of light and the spatial configuration of a space affect the visual comfort therein. Light includes daylight, sky illuminance, reflected light, shadows, and artificial lighting. Spatial components include the elements that define enclosures, such as the floor, walls, ceiling, and external elements, such as projections, vegetation, and the surrounding structures (Chan & Liu, 2018). Researchers usually use daylight and glare analysis to quantify visual comfort within a space (Asfour, 2020; Fahmy, Fahmy, & Elwy, 2016). Daylight is the visible part of global solar radiation, i.e. all direct and indirect sunlight (Bandopadhyay, 2010). At the same time, glare is the sensation produced by bright areas within the field of view, and users may experience discomfort glare or disability glare (EN12464-1 2002).
Syncing with the Sky: Daylight-Driven Circadian Lighting Design
Published in LEUKOS, 2021
Nathan Altenberg Vaz, Mehlika Inanici
Most of the current practice of circadian lighting design is focused on the effect of artificial light on the circadian pacemaker, as it can have both a desirable and an adverse effect on human well-being (Bellia et al. 2013; Chen et al. 2020; Zielinska-Dabkowska 2018). While it is important to understand and quantify the effect of artificial light sources on circadian entrainment in order to provide supplemental stimulus when needed, and prevent undesirable stimulus that can have an adverse effect on human well-being, it is also essential to understand the effect of the built environment on the natural light that humans have evolved to be entrained to. This distinction is similar to the distinction between electric lighting design and daylighting, in that electric lighting can be used for supplemental purposes to provide light when necessary during the day, but ideally the effective use of daylight is maximized in order to reduce energy usage and provide natural and high-quality light for human well-being.