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•The paper introduces a new passive collector design for the purpose of light collection for daylighting.•Maintain uniform lighting levels for the most part of the day under clear sky ...sun.•The average illuminance of around 400 lx was observed on the floor of the experimental room for the most part of the day.•The performance of proposed designed collectors leads under the low-altitude sun when compared to conventional designs.
A tubular skylight (TS) is an effective system for transporting natural sunlight into the building interiors. However, the passive nature of the system may not account for the changing orientation of the sun and the conventional daylight collector designs like transparent dome are less effective under low altitude sun. This paper focuses on the performance evaluation of specifically designed TS having rectilinear parabolic-profile reflectors integrated with plane surface reflectors and wedge-shaped prism for daylight collection. The designed configuration redirects the low altitude incident rays efficiently into a vertical mirror light pipe having a rectangular cross-section and aims at giving desired levels of lighting throughout the sunny day. Numerical analysis of the same was carried out for various sky conditions. Experimental results for the proposed TS design show improved lighting levels during the low-altitude sun and reduced but consistent lighting during the mid-day. Average illuminance of ~ 400 lx was observed on the floor of the experiment room for the most part of the day. Along with capturing beam sunlight a significant amount of diffuse daylight capturing ability under clear sky conditions is observed using the proposed TS. The average illuminance value obtained on the work plane during winter solstice through the most optimized configured TS was more than twice the lighting value achieved by a conventional daylight-collecting transparent dome and almost twice the lighting value achieved by a TS with a prismatic dome collector. Under overcast sky conditions, the performance of the proposed configuration of TS is at par.
•An active daylighting system was explored by mixing sunlight and artificial light for constant illumination.•The system will allow the realization of solar constant lighting and energy efficiency in ...indoor illumination.•Operation of the system could noticeably cut down the electric energy consumption for indoor lighting in buildings.•A light source with a CCT of 5000 K in conjunction with sunlight delivers streams of light (mixed) very close to sunlight itself (bright daylight).
The goal of this work was to develop an active daylighting system where constant illumination is made possible by mixing sunlight and artificial light as needed. A Fresnel lens mounted on a dual axis solar tracker was used to collect sunlight, which was then transmitted by an optical fiber cable. During its transmission, sunlight was mixed with light from an artificial light source (LED lamp, 120 W) to produce a constant flux of light before being discharged into a space. A constant level of illumination was achieved on the task plane throughout the system's operation. This system differs from other active daylighting systems, which require a sensor feedback from some reference point to control the amount of additional light provided to the interior spaces. It is expected that the system will enable solar constant lighting and energy efficiency in indoor illumination to be achieved. Based on a luminous efficacy of 17 lm/W for the LED lamp and operation of 8 h/day for 110 days annually, it is projected that 174 kWh of electric energy could be saved by the present system.
Display omitted Constant illumination system mixing sunlight and artificial light.
•A fully new scheme of the daylighting using optical-fiber-less design and hybrid system.•Aiming to guide light deeply and efficiently for a given multi-storey building.•The optical efficiency and ...energy saving can reach 63.7 % and 46.5%, respectively.
In this study, the fully new scheme of the daylighting system is devised and a few avenues are proposed toward large scale illumination area with the highly efficient luminous flux and modest cost. Rather than a previously common design, consisting of a sole system, we work out two subsystems for a generic daylighting system: outdoor and indoor subsystems. For the outdoor subsystem, aiming to guide light deeply and efficiently for a given multi-storey building, we first capitalize on a simple design of two mirrors to collect the sunlight and transport it in free-space, which negligibly penalizes the optical loss. To guide light to each particular area inside building, we further propose two options for the indoor subsystem taking into consideration between cost and performance: first with the Fresnel lens + circular plastic optical fiber (POF) bundle and second with the waveguide concentrator + flat POF bundle. The quantitative assessment unravels that the optical efficiency of the latter is higher than that of the former, 63.7 % vs 48.7 %. Still, the real implementation of the Fresnel lens + circular POF is more prone and we indeed demonstrate a principle-of-concept system. Such design also preferably implements with a LED panel, in an embodiment of a so-called hybrid daylighting system, to grant light in overcast and night-time situations. This proposed daylighting system also enables exceptional merit in calculated energy saving, up to roughly 46.5% in a year with sunlight condition as in Ho Chi Minh City (Vietnam), as electrical light is used properly and barely. All things taken into account, this approach indicates a likely perspective for fostering a new generation of the daylighting system that making use of sparingly optical fiber.
Excellent daylighting in buildings is beneficial to protect the physical and mental health of users. After introducing the daylighting of the building, this paper used the genetic algorithm (GA) ...optimized by co-evolution to optimize the daylighting. Then, a one-story L-shaped accommodation house in Zhengzhou, Henan Province was taken as a case for analysis. The effectiveness of the Daysim software used for calculating the building lighting indicator was tested. Then, the performance of the improved GA with different daylighting indicators as fitness values was compared. Finally, the optimization performance of the particle swarm optimization (PSO) algorithm, the traditional GA, and the improved GA were compared. The results showed that the daylighting indicators simulated by Daysim were significantly correlated with the measured data, suggesting its effectiveness. The improved GA using dynamic daylighting indicators as fitness values had better optimization performance. Compared with the other two algortihms, the improved GA had better optimization performance.
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•Eight-fold Fresnel lens with fiber connector for daylighting.•Bi-layer prismatic diffuser for optical fibers to increase illuminance uniformity.•Comparison of raytracing simulation ...results for fiber-based daylighting systems.
Recently, advanced daylighting has become an important part of sustainable architecture design to increase visual comfort and illuminate deep interior spaces. Daylighting systems based on solar concentrators and fiber optical transmission have attracted a lot of research attention. In this paper, the authors propose a daylight collection and transmission design to transmit the concentrated light more uniformly into the optical fibers employing two optical elements: an eight-fold Fresnel lens as the primary optical element (POE) and an octagonal spherical fiber connector as the secondary optical element (SOE). In addition, a bi-layer prismatic optical panel acting as a diffuser is proposed in order to distribute light more uniformly in the interior space. The proposed designs of those optical elements are verified by ray-tracing simulation for achieving the required illumination level. The simulation results have shown that the combination of the proposed POE and SOE transmits light more uniformly into the bundle of optical fibers, and meanwhile the light diffuser provides relatively even illuminance distribution on a working plane. This shows a considerable advancement to the optical fiber daylighting designs. A case study shows the transmission efficiency of the proposed design is about 10% better than other common designs.
Abstract
The main objective for this paper is focused on an evaluation of sun-shading daylighting in a four-star hotel design mass. The daylighting has potential and considers as the best strategy ...for energy saving. Lowering energy costs can directly increase revenue, coupled with the potential for gradual increase in PLN electricity. Apart from financial and service benefits, saving energy is also a form of concern for the sustainability of the environment which has an impact on social life. The method that used in this paper is quantitative simulation, which is presented in the paper by specification of daylighting in a four-star hotel design on solstice day, 21
st
December. The simulation is done by Velux Daylighting Visualizer, with a couple of lost variables. The simulation for this condition represents two extreme cases for maximum and minimum daylight levels in annual evaluation.
Despite the abundance of daylight in hot desert climates, deep-plan office buildings still lack the provision of sufficient daylight. Although tubular daylighting devices (TDDs) offer a potential ...solution, they may have visual and economic consequences. Therefore, the present study evaluated the visual comfort, overall energy consumption, and economic feasibility of multiple TDD configurations. Typical deep-plan office space has been simulated based on a field-validated simulation process to evaluate visual comfort and energy consumption. The WLCC method was used to assess the economic feasibility. The reference case was illuminated using LED and a dimming control system with photosensors placed in cardinal orientations. Supplementary daylight was provided using different configurations of vertical and horizontal TDDs. Window shading devices were used to enhance visual comfort. The study found that vertical TDDs perform better than horizontal TDDs in terms of illumination uniformity and economic feasibility. They reduced the electric lighting load by up to 21%. However, the utilization of the TDDs in the hot desert climate has the potential to significantly increase indoor heat gain, which, in turn, increases the cooling energy. It is found that the additional energy required for cooling far outweighs the energy-saving benefits gained by TDDs. Accordingly, thermal issues associated with the utilization of TDDs should be investigated to allow widespread use of them in arid regions where high solar radiation is available throughout the year. Moreover, other daylighting-associated benefits, such as users’ productivity enhancement and health and mood improvement, should be considered to promote the usage of TDDs and boost their economic returns.
•The daylighting performance of vertical and horizontal TDDs was examined.•Comparison analysis of TDDs and LEDs with dimming photosensor.•TDDs decreased the overall energy consumption by only 3.6%.•The vertical TDDs in hot deserts increase significantly the indoor heat gain.•The estimated payback period (PP) in dimming devices ranged from 2.9 to 4.4 years.
•Optimal set of DLSs is determined and save up to 40% in total energy consumption.•DLSs with shading obtain highest reduction 24–38% in total energy consumption.•Horizontal sun-breaker, double-slats ...is the best for improving energy efficiency.•A utilization guide is developed to optimize energy efficiency at the design stage.
The absence or improper use of shading on the glazing of building windows causes overheating which increases both cooling load and glare, especially in the hot desert climate. However, integrating Daylighting Systems appropriately into building windows can contribute to reducing energy consumption by effectively utilizing daylight as a renewable resource instead of depending only on artificial light. This can help in achieving green, sustainable, high performance, and energy-efficient buildings. This paper proposes a set of integrated Daylighting Systems into building windows to optimize the energy efficiency performance of office buildings in the hot desert climate.
The integration of individual and collective Daylighting Systems with different configurations are explored to generate an extensive set composed of 87 alternatives in three different orientations. The energy simulation is conducted for these alternatives to investigate their performance on reducing the electric energy consumption of cooling and artificial lighting. The optimal set of energy-efficient integrated Daylighting Systems is determined based on the highest performance of reducing energy consumption for cooling and lighting while maintaining visual and thermal comfort. This optimal set of integrations is formulated into a multi-level utilization guide for facilitating the appropriate selection of optimal energy-efficient Daylighting Systems into building windows. This utilization guide will assist building designers to optimize the energy efficiency performance of buildings by selecting the most appropriate Daylighting Systems to be integrated into building windows. Such performance-based utilization guide will aid designers in making decisions from the perspectives of energy efficiency, and visual and thermal comfort.
•An asymmetric concentrator with a large acceptance range of 10°–85° and high optical efficiency has been designed.•An multifunctional asymmetric concentrator-PV type window was designed.•The shading ...effect was analyzed and an optimization strategy was proposed to reduce the influence of it.•An typical office room integrated with the multifunctional asymmetric concentrator-PV type window was modelled and analysed.•The daylighting performance and concentrating PV performance were analyzed.
The development of PV type window for building south wall integration is a promising concept, which provides a solution to the energy crisis and environment pollution problem. Thus in this paper, an asymmetric concentrator is proposed, and through the simple concentrator array optimization process, the asymmetric concentrator-PV type window can be designed, which provides the electricity generation and incorporates the function of daylighting at the same time. The optical models for the concentrator design and daylighting analysis are built and experimentally validated. The optical performance of the asymmetric concentrator has been analyzed. Considering that the incidence angles of sunrays on the building south wall remain at a high level throughout the year, the shading effect should be seriously considered. In order to reduce the shading effect between each concentrator array, the shading effect has been predicted and an arrangement optimization strategy by setting gaps between each concentrator array is presented. It was found that these gaps could alleviate the shading effect, which will also further allow the function of daylighting. Through the simulation analysis, it was found that the asymmetric concentrator can attain a large acceptance range of 10°–85° while maintaining high optical efficiency and the asymmetric concentrator-PV type window can achieve the daylighting efficiency of 4.0% to 21.8%, thus it can confirm good annual concentrating PV and daylighting performance. At last, a typical office room (the length, width and height are 3.4 m × 3.0 m × 3.3 m) installed with the asymmetric concentrator-PV type window is modelled and the illuminance distribution on the ground floor at various incidence angles is determined with the solar irradiance set at 500 W m−2. Besides of that, the energy distribution for the electricity generation and daylighting at various incidence angles is also indicated. Through the analysis, the asymmetric concentrator-PV type window is proved suitable for building south wall integration, which can efficiently use the solar energy for the domestic use, in the forms of electricity and daylighting.
•Presents a new method to improve performance of passive strategies in early design.•Form finding to achieve daylighting and whole building energy optimization.•Automatically incorporates local urban ...geometry in simulation process.•Case study application in four diverse climates and real urban sites.•Solutions exceed performance of current high performance building reference.
To achieve low and zero net energy performance objectives in buildings, designers must make optimal use of passive environmental design strategies. The objective of this research is to demonstrate the application of a novel Passive Performance Optimization Framework (PPOF) to improve the performance of daylighting, solar control, and natural ventilation strategies in the early design stages of architectural projects. The PPOF is executed through a novel, simulation-based parametric modeling workflow capable of optimizing building geometry, building orientation, fenestration configurations, and other building parameters in response to program requirements, site-specific building adjacencies, and climate-based daylighting and whole-building energy use performance metrics. The applicability of the workflow is quantified by comparing results from the workflow to an ASHRAE 90.1 compliant reference model for four different climate zones, incorporating real sites and urban overshadowing conditions. Results show that the PPOF can deliver between a 4% and 17% reduction in Energy Use Intensity (EUI) while simultaneously improving daylighting performance by between 27% and 65% depending on the local site and climatic conditions. The PPOF and simulation-based workflow help to make generative modeling, informed by powerful energy and lighting simulation engines, more accessible to designers working on regular projects and schedules to create high-performance buildings.
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