A Review of Light Shelf Designs for Daylit Environments

Kontadakis, A.; Tsangrassoulis, Aris; Doulos, Lambros T.; Zerefos, Stelios

doi:10.3390/su10010071

Cited by 65 publications

(50 citation statements)

References 50 publications

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“…Light shelves can be installed totally inside, totally outside, or partially inside and outside the glazed area. The outer part of the device is able to shade the glass surface, while the inner one reflects solar radiations, increasing illuminance away from the window and producing a uniform distribution of light on the work plane [36]. Freewan et al [37], after analysing the factors affecting the light shelves' performances, underline the importance of the ceiling geometrical shape, while Berardi et al [38] highlight how the WWR affects the diffusion of daylight obtained using light shelves.…”

Section: Introductionmentioning

confidence: 99%

Experimental Analysis of the Performance of Light Shelves in Different Geometrical Configurations Through the Scale Model Approach

Zazzini¹,

Romano²,

Lorenzo³

et al. 2020

Journal of Daylighting

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Daylight plays a significant role in achieving energy saving and comfort in buildings. It is in accordance with the human circadian rhythms and allows the best visual conditions in work environments and residential buildings. Recently, numerous researchers have focused their attention on the performance of technological devices able to increase natural light availability in interior areas of buildings. Among them, light shelves are commonly used with the aim of improving the depth of daylight penetration, trying to reduce the nonuniform diffusion of light entering from vertical windows. In this paper, the authors propose six different configurations of an internalexternal light shelf and analyse their performance using the experimental scale model approach under real sky. Although the method is not very accurate as deduced from literature on this topic, the authors still demonstrate its usefulness in examining different geometric configurations of light shelves. In fact, even if the results highlight inaccuracies in the method used, which are accentuated under direct sun light, they are useful for considerations in the comparative analysis, particularly in regard to data logged under partially completely cloudy skies albeit with the awareness that light shelves' effectiveness is improved under direct sun light. Despite its limits, the method is simple to use and can be considered efficient in allowing the authors to carry out considerations regarding the performance of the system analysed. Among the six different configurations proposed two seem to be the most efficient and are characterized by the presence of an internal highly reflecting surface applied on the ceiling and an external one with two different inclination angles (10° and 20°).

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Section: Introductionmentioning

confidence: 99%

Experimental Analysis of the Performance of Light Shelves in Different Geometrical Configurations Through the Scale Model Approach

Zazzini¹,

Romano²,

Lorenzo³

et al. 2020

Journal of Daylighting

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“…In sunlit situations, the natural daylight often has to be blocked to prohibit glare and overheating. Beside transparent windows with shelfs and reflecting blinds [13], other constructions exist like translucent wall materials or waveguide systems especially to transport daylight also to façade distant spaces.…”

Section: Lighting Systems and Conservationsmentioning

confidence: 99%

Daylight Performance of a Translucent Textile Membrane Roof with Thermal Insulation

Gürlich¹,

Reber²,

Biesinger³

et al. 2018

Preprint

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Daylight usage in buildings improves visual comfort and lowers the final energy demand for artificial lighting. The question that always occurs is how much conservation can be achieved? New or rare materials and constructions have a lack of information about their application. Therefore, the current investigation quantifies the daylight and energy performance of a rare multilayer textile membrane roof. A translucent, thermal insulation with a glass fibre fleece between the two roof membranes combines daylight usage and heating demand reduction. A sports hall built in 2017 is used as a case study building with 2300 m 2 membrane roof surface. The optical properties of the roof construction are measured with a total visual light transmittance τv of 0.72 % for a clean surface. A climate-based annual daylight modelling delivers daylight indicators for different construction scenarios. The results show that in comparison to only one glass facade, the additional translucent and thermally insulated membrane roof construction increases the annual daylight autonomy (DA700) from 0 % to 1.5 % and the continuous DA700 from 15% to 38 %. In the roof-covered areas of the sport field, this results in a 30 % reduction of the electricity demand for artificial lighting from 19.7 to 13.8 kWhel/m²/a, when a dimming control is used. The study also found out, that the influence of the soiling of one layer decreases its light transmittance by a factor 0.81. Two soiled layers lower τv by a factor 0.66 to 0.47 %. This increases the electricity demand for lighting by only 12 %. The results should be very valuable as a comparison and benchmark for planners and future buildings of a similar type.

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“…As energy consumption has become a crucial factor for tunnel design, a number of control systems based on daylight compensation have been investigated for installation in the tunnel entrances [44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Revision of Threshold Luminance Levels in Tunnels Aiming to Minimize Energy Consumption at No Cost: Methodology and Case Studies

Doulos

Sioutis²,

Tsangrassoulis

et al. 2020

Energies

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Because of the absence of lighting calculation tools at the initial stage of tunnel design, the lighting systems are usually over-dimensioned, leading to over illumination and increased energy consumption. For this reason, a fine-tuning method for switching lighting stages according to the traffic weighted L20 luminance is proposed at no additional cost. The method was applied in a real –case scenario, where L20 luminance of the access zone at eleven (11) existing tunnels was calculated. The traffic weighted method of CR14380 was used in order to calculate the actual luminance levels for the entrance zone. The new transition zone, which decreases luminance curves, was produced and compared with the existing ones. Thus, a new switching control was proposed and programed for the Supervisory Control and Data Acquisition (SCADA) system of the tunnel. The signals of the corresponding eleven L20 meters for a period of eight days were used and the corresponding annual energy consumptions were calculated using the proposed switching program for each tunnel. The results were compared with a number of scenarios in which the existing lighting system was retrofitted with Lighting Emitting Diodes (LED) luminaires. In these scenarios, the new luminaire arrangement was based not only on the existing luminance demand value for the threshold zone, but also on the newly proposed one with two different control techniques (continuous dimming and 10% step dimming). The fine-tuning method for switching resulted in energy savings between 11% and 54% depending on the tunnel when the scenario of the existing installation at no extra cost was used. Energy savings, when LED luminaires were installed, varied between 57% (for the scenario with existing luminance demand value for the threshold zone and 10% step dimming) and 85% (for the scenario with the new calculated luminance demand and continuous dimming).

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A Review of Light Shelf Designs for Daylit Environments

Cited by 65 publications

References 50 publications

Experimental Analysis of the Performance of Light Shelves in Different Geometrical Configurations Through the Scale Model Approach

Experimental Analysis of the Performance of Light Shelves in Different Geometrical Configurations Through the Scale Model Approach

Daylight Performance of a Translucent Textile Membrane Roof with Thermal Insulation

Revision of Threshold Luminance Levels in Tunnels Aiming to Minimize Energy Consumption at No Cost: Methodology and Case Studies

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