Tubular Daylight Guidance Systems Research Articles

Thermal analysis of tubular daylight guidance system on an insulated flat roof with overlying soil

As an emerging passive daylighting technology, tubular daylight guidance systems (TDGSs) are increasingly used in low-energy buildings. However, TDGS may become a thermal bridge to increase indoor air conditioning load. To avoid an increase in total energy consumption, the thermal analysis of a flat roof section with a TDGS is simulated using CFD in this work. Additionally, the simulation compares the heat transfer performance of a conventional TDGS with eight different designs TDGS that contain additional glass unit. The findings show that TDGS has a thermal bridging effect on an insulated flat roof with overlying soil. The additional glass unit in the middle of the conventional TDGS with diameter 500 mm decreases its overall heat transfer coefficient by 53 %. Further, the same thickness of glass is divided into 4 layers and evenly distributed inside the TDGS with diameter 500 mm, which can reduce the total heat transfer coefficient of the conventional TDGS by 67 %.

Enhancing Daylight Availability in Historical Buildings through Tubular Daylight Guidance Systems: A Simulation-Based Study

This simulation-based study investigates the potential of tubular daylight guidance systems (TDGS) to enhance daylight availability in historical buildings. Historical buildings often face challenges in providing sufficient daylight to non-lit areas without altering the building’s facade. TDGS offer a passive, building-integrated solution that redirects daylight to target areas while preserving the building’s originality. The study focuses on a historic passage building without ground floor openings and aims to improve visual comfort and daylight availability. Climate Studio software is used to assess the current daylighting conditions and to simulate various scenarios for TDGS implementation. The study considers four TDGS alternatives with different diameters, evaluating their impact on useful daylight illuminance (UDI) and spatial daylight autonomy (sDA). The findings reveal significant increases in UDI and sDA, ranging from 68.7 % to 403.7 %, and from 79.9 % to 1813.6 %, respectively, depending on the tube diameter. These results underscore the importance of daylight tube diameter in increasing the availability and distribution of useful daylight. The study emphasizes the potential of TDGS to optimize daylighting experiences in historical buildings with limited daylight

A Design Proposal for Improving Daylight Availability of a Deep-Plan Classroom by Using Tubular Daylight Guidance Systems and Movable Shading Devices

The use of daylight in educational settings has a significant impact on the well-being, attention, and academic achievement of students. However, providing adequate daylighting without glare can be difficult, especially in deep-plan layout classrooms, because daylight is not constant and its strength varies with distance from the façade, necessitating the use of additional solutions frequently. In this study, tubular daylight guidance systems (TDGS) and movable shading devices are proposed to increase daylight availability in the Yaşar University Faculty of Architecture Temporary Studio, which has a deep plan layout and receives daylight only from the southeast facade. The objective was to meet the LEED daylight evaluation requirements for each zone, which require sDA to be at least 55% and ASE to be at most 10% in the selected analysis area. To propose TDGS and movable shadings with the most efficient angles and positions; Rhinoceros, Grasshopper, and Climate Studio were used, and simulation results were validated by real-time measurements. The design proposal simulation results achieved a significant increase in daylight availability in the rear part of the room (zone 2-3), while glare was diminished near the façade (zone1). The proposed design strategy improved daylight availability through the room, demonstrating that the systems perform well together.

Discussion about calculation method of light transmission efficiencies of elbows in cylindrical light pipes

In some tubular daylight guidance systems (TDGSs), one or more elbows have to be incorporated to change the direction of light transmission for adapting to complex building structures, although an elbow will cause a more light loss than for the equivalent length of a straight pipe and reduce the whole daylighting efficiency. Generally, one elbow’s light transmission efficiency (LTE) is calculated by comparing the measured or calculated LTE values of one straight pipe and the other pipe with this elbow inserted into the former straight one. In this article, firstly through some formula derivations, it is noted this method is based on the assumptions that the insertion of an elbow does not affect the LTEs of its sequent sections, and the identical straight sections or elbows have the same LTEs, regardless of their positions in the whole light pipe; Nevertheless, the assumptions have been refuted after the straight pipes’ LTEs from related literature being deeply analyzed; Moreover, the other conclusions have been drawn that the LTE of a certain straight section or an elbow is not a constant value and also be affected by its position in the whole pipe, so the present LTE calculation method of elbows is wrong and should be modified.

Effects of tubular daylight guidance systems on the daylighting performance and energy savings in office buildings under different climate zones

Over the recent years, the energy use of artificial lighting has been gradually increasing in office buildings. Tubular daylight guidance system (TDGS) is an innovative daylighting technology, which is used to transport daylight into the core of a building. In this study, the effects of the tube radius of TDGSs, window-to-wall ratio (WWR), and window orientation on the indoor illuminance, artificial lighting electricity consumption, and heating/cooling loads of an office room are investigated for the five climate zones in China by both numerical simulations and experiments. The model is developed using Radiance and Ecotect, and its feasibility is validated by comparing the simulated indoor illuminance distributions with the field measurements. The results demonstrate that the increase in the tube radius and the decrease in the WWR and the utilization of a north-facing window can improve the daylighting performance and energy savings of the TDGSs. In general, the TDGSs can reduce the artificial lighting electricity consumption and heating load while increasing the cooling load of the office room. Due to the implementation of TDGSs, the maximum potential energy savings (on the lighting energy use and the heating/cooling energy use) are 27.6% in Kunming (moderate climate), 13.5% in Chengdu (hot summer and cold winter), 10.6% in Guangzhou (hot summer and warm winter), 10.3% in Beijing (cold), and 5.0% in Harbin (severe cold).

Thermal and spectral impact of building integrated Mirrored Light Pipe to human circadian rhythms and thermal environment

ABSTRACT Light holds an important place in the way of life of humans. The first type of lighting which could be exploited was daylight. Tubular Daylight Guidance Systems (TDGS) transport and distribute this daylight inside a building. This article focuses on one of the best known: the Mirrored Light Pipe. MLPs are multiple specular reflectance transporters. This paper presents (i) state of the art on thermal and spectral studies on light pipes from 1998 to 2021 and (ii) proposes an experimental analysis on MLP in the climatic environment with a high solar resource for different spectral bands of the daylight spectrum. The results show that the thermal impact of the light pipe is limited. Moreover, it is demonstrated that this device promotes natural circadian rhythms. A comparison with artificial lighting highlights this device as an ideal solution for bioclimatic building design. HIGHLIGHTS A short review on experimental and numerical thermal results on Mirrored Light Pipe (MLP) New experimental observations for the thermal aspect of MLP in high solar potential climate Evaluation of the MLP efficiency on human circadian rhythms.

Experimental investigation of dust accumulation effect on the performance of tubular daylight guidance systems

Tubular daylight guidance systems were developed to introduce daylight into the building’s core. Operating the system in desert climate regions, where both solar irradiance and dust resources are abundant, exposes them to dust accumulation that significantly reduces the system’s efficiency. An experimental investigation was conducted in Cairo to understanding dirt accumulation patterns and impact, and to recommend suitable cleaning procedures. It was found that dust accumulation during three rainless periods, of 44 days each, could reduce the illuminance transmittance by up to 38%. The dust accumulation was found to decrease the system efficiency in a near-linear fashion with a 0.5% daily reduction. The highest illuminance transmittance magnitude and ratio were observed at midday, followed by the morning period and then the afternoon period. Similarly, the transmittance loss by the end of the experiment was found to be around 31%, 26% and 13% at noon, morning and afternoon respectively. It was found that the transmittance loss under a clear sky is up to 25% more than that under a cloudy sky. Further work needs to be done to examine other meteorological factors. Based on the study findings, it is recommended to clean the solar devices bimonthly to restore the system’s efficiency.

Multi-layered and multi-dimensional suitability evaluation of tubular daylight guidance systems

Aimed at the promotion of tubular daylight guidance systems, a set of multi-layered and multi-dimensional methods for suitability are explored in this paper. Among them, “Multi-layered” refers to the staged evaluation based on different types of influencing factors, and “multi-dimensional” refers to technology performance, economic benefit, and human satisfaction, considering different concerns of national standards, developers, and user groups. The three layers in this method are 1) preliminary evaluation based on the pre-requisites for technology application, 2) single-dimensional evaluation based on demand and 3) comprehensive evaluation based on multi-dimensional suitability. In layer 1, screening principles and screening methods are formulated; in layer 2, the weight of the evaluation index is obtained by the binary comparative analysis method based on the expert questionnaire, and the evaluation result is given by the scoring method; and in layer 3, the TOPSIS (Technique for Order reference by Similarity to an Ideal Solution) is used to obtain the queueing index value, and the weights are calculated by combining subjective and objective methods. The final evaluation is obtained by the linear weighted sum method and exponential evaluation baseline method. The tubular daylight guidance systems in a teaching building of a university in Tianjin were taken as an analysis case to demonstrate the application of this method. The results indicate that the weighted final evaluation value of the case is 0.16 and the application of case is “relatively appropriate”. This approach achieves the multi-dimensional evaluation of the suitability of tubular daylight guidance systems and makes the evaluation more reasonable.

Technological Review of Tubular Daylight Guide System from 1982 to 2020

T.D.G.S., “Tubular Daylight Guidance Systems”, are natural lighting processes based on the transport of light. In 1990, they were judged by Littlefair as the most innovative technology in daylighting [1]. From 1982 to 2020, this paper is a state of the art on the different processes of tubular daylight guide systems. The key words used to carry out the census are light pipe; light tube; light guide; sun pipes; solar pipes; solar light pipes; daylight pipes; tubular skylight; sun scoop; tubular daylighting device; tubular daylight guide systems; mirrored light pipe. A classification by type of process is proposed (collection, transport or diffusion) for each technology identified in the literature.

Technological Review of Tubular Daylight Guide System from 1982 to 2020

T.D.G.S., “Tubular Daylight Guidance Systems”, are natural lighting processes based on the transport of light. In 1990, they were judged by Littlefair as the most innovative technology in daylighting [1]. From 1982 to 2020, this paper is a state of the art on the different processes of tubular daylight guide systems. The key words used to carry out the census are light pipe; light tube; light guide; sun pipes; solar pipes; solar light pipes; daylight pipes; tubular skylight; sun scoop; tubular daylighting device; tubular daylight guide systems; mirrored light pipe. A classification by type of process is proposed (collection, transport or diffusion) for each technology identified in the literature.

Proposal of the Tubular Daylight System Using Acrylonitrile Butadiene Styrene (ABS) Metalized with Aluminum for Reflective Tube Structure

In the search for alternatives to reduce the consumption of electric energy, the possibility of using natural light for lighting through TDD (tubular daylight devices) or TDGS (tubular daylight guidance systems) appears. These natural luminaires are used in rooms where you want to save electricity and enjoy the benefits of natural light. The present work proposes the construction of a tubular system for the conduction of natural light that replaces aluminum with silver (currently marketed by several companies) by polymer metallized with aluminum, offering a low cost. The polymer acrylonitrile butadiene styrene (ABS), coated with aluminum by physical vapor deposition (ionization), was evaluated for some tests to verify characteristics of the structure and the metallized surface. After the tests, the construction of the reflective tube was performed and validated in a real scale of application. The results proved the technical viability of the proposed tube construction for the realization of direct sunlight for illumination using polymeric material. Although it has produced 35% less than the reference tube, it can be marketed at an estimated cost of 50% less.

Passive Tubular Daylight Guidance System Survey

Daylight levels decrease asymptotically with distance from the window so that a disproportionate amount of daylight/solar gain must be introduced into the front of the room to achieve small increases in daylight deep inside at the back. Several systems exist to redirect daylight into areas of buildings that cannot be lit by traditional glazing. One major generic group is known as ‘beam daylight’ - redirects sunlight by adding reflective or refracting elements to conventional windows. The second major group is known as Tubular Daylight Guidance Systems (TDGS). Tubular daylight guidance systems are linear structures that channel daylight by means of optical interactions into the core of a building.The paper presents a case-study for a passive TDGS installed in a residential building in Cluj-Napoca, Romania. Field measurements are presented as well as software simulation results (DIALux, Lux Calculator). Based on the official numbers of dwellings provided by the Romanian National Institute of Statistics and the energy savings presented in the case-study, some predictions were made regarding the energy saving potential of passive tubular daylight systems over Romania.

LRT Digest 2 Tubular daylight guidance systems

Executive summaryThis Digest concerns passive tubular daylight guidance systems (TDGS), the most commercially successful method of daylight guidance. TDGS were introduced some 20 years ago and thus...

Light transmission efficiency of daylight guidance systems: An assessment approach based on simulations and measurements in a sun/sky simulator

Abstract New and more advanced guidance systems are nowadays available, allowing bringing natural light into buildings and offering potentials for energy savings associated to well-being for occupants. From a design point of view, the key factor is the knowledge of their photometric performances in terms of global light transmission efficiency, so as to predict the daylight availability in an interior space due to an array of guidance systems (or, the other way around, to predict the number of pipes needed to produce a minimum natural light illuminance according to standard requirement) through known analytical methods such as the lumen method. In spite of this, determining the global light transmission efficiency of advanced guidance systems is a quite complicate matter because of the redirecting optical properties these elements rely on even in the case of simple typologies (for instance, passive domes with micro-prismatic profiles and micro-prismatic or holographic films used as pipe’s coating). This paper presents an approach to characterize photometric performances of tubular daylight guidance systems in terms of light transmission efficiency: the global system efficiency is the result of the product of the efficiencies of the three individual components (collector, pipe and diffuser) and each efficiency is determined as the ratio of the flux emitted through the output window to the flux hitting the input window, accounting for both the beam and the diffuse efficiency. The approach, based on both measurements on physical models and simulations, was applied to different typologies of pipes and passive collectors and the obtained data were used to eventually calculate the global efficiency for the analyzed system.

Limitations in current day lighting related solar concentration devices: A critical review

This study introduces the day lighting related solar concentration devices such as light pipes (or tubular daylight guidance systems), optical fibers for light transport, conventional solar concentrators and luminescent solar concentrators (LSC). The principles of study, advantages and disadvantages for application of these day lighting related devices have been explained. Daylight has a disadvantage of not being able to reach deeper areas in a building such as storerooms, basements and corridors and it also brings the heat gain with the light. Light pipes and optical fibers were expected to transfer daylight to unreached areas, but light pipes have their difficulties in wiring and the optical fiber needs a pointolite for the light transportation. Solar concentrators are only sensitive for the beam radiation and they function poorly in overcast sky conditions. Even under a clear sky condition, trackers are always needed for conventional solar concentrators. Static concentrators always come with a poor concentration rate without a tracker and the light concentrated by normal luminescent solar concentrators could not be transported by optical fibers to a remote place since the light produced by LSCs is not a pointolite. Future studies especially cross disciplinary researches on developing new solar concentration devices in mitigating those limitations as discussed in this study are highly recommended.

User attitudes toward tubular daylight guidance systems

The study reports quantity and quality of daylight delivered by tubular daylight guidance systems in large open plan offices. The daylight contribution was of the order of 25% of total design workstation illuminance giving daylight penetration factors of between 0.5% and 1.3%. User views suggest that tubular daylight guidance systems were inferior to windows in delivery of both quantity and quality of daylight although satisfaction with some aspects improves with increased daylight penetration

Tubular guidance systems for daylight: UK case studies

Tubular daylight guidance systems (TDGS) are linear devices that channel daylight into the core of a building. The experience of some of the first uses of TDGS is explored in actual buildings in UK temperate latitudes. The nature of the systems and the factors influencing the costs and various benefits that contribute value are identified. Lighting systems in working offices, lit by electric lighting and daylight guidance, were surveyed. Data on the physical characteristics of the systems, lighting conditions achieved, and user views were collected. The results formed the input to a cost and value analysis which permitted the economic limits of the systems to be evaluated. A number of daylight and environmental benefits were identified as value items, but the systems were clearly uneconomic in cost terms as presently configured and used. Long-term cost–value was compared with electric lighting alternatives making assumptions about future energy costs and system configurations. Some pitfalls of attempting to integrate innovative technology into existing lighting systems are identified and remedies suggested. Les systèmes tubulaires de guidage de la lumière du jour (TDGS) sont des dispositifs linéaires qui canalisent la lumière du jour jusqu'au centre d'un bâtiment. L'auteur analyse quelques-unes des premières applications des TDGS dans des bâtiments existants au Royaume-Uni, sous des latitudes tempérées. Il identifie la nature des systèmes et les facteurs qui ont des incidences sur les coûts et les divers avantages qui contribuent à la valeur de ces systèmes. Il étudie les systèmes d'éclairage électrique et de guidage de la lumière du jour utilisés dans les bureaux. Il a recueilli des données sur les caractéristiques physiques de ces systèmes, sur les conditions d'éclairage obtenues et sur le point de vue des utilisateurs. Ces résultats ont servi à une analyse de coût et de valeur qui a permis d'évaluer les limites économiques de ces systèmes. On a identifié un certain nombre d'avantages de la lumière du jour et de l'environnement comme étant des éléments intéressants mais il est clair que ces systèmes ne sont pas rentables en termes de coût tel qu'ils sont actuellement configurés et utilisés. On a comparé l'ensemble coût-valeur à long terme à des alternatives d'éclairage électrique et élaboré des hypothèses sur l'avenir des coûts énergétiques et des configurations de tels systèmes. On a identifié quelques obstacles à l'intégration de technologies novatrices dans les systèmes d'éclairage existant et on a suggéré des solutions. Mots clés: Mots-clés: technologies alternatives, lumière du jour, retour d'information, systèmes de guidage, conduits de lumière, systèmes d'éclairage, conception de bureaux, evaluation technologique, valeur

A field study of tubular daylight guidance installations

The study reports achieved conditions and user views in 14 buildings equipped with passive zenithal tubular daylight guidance systems and electric lighting and, in some cases, windows. The daylight contribution was in the order of 35% of total design workstation illuminance giving daylight factors of between 0.5 and 1.0%. User views elicited by questionnaire suggest that tubular daylight guidance systems (TDGS) were inferior to windows in delivery of both quantity and quality of daylight. Guidelines for the design of future systems are suggested.

Tubular guidance systems for daylight: Achieved and predicted installation performances

Tubular daylight-guidance systems are linear devices that channel daylight into the core of a building. The development, over the last decade, of materials with high specular reflectance has led to a large number of passive zenithal systems; the most commercially successful type of daylight guidance being installed in many parts of the world. The rapid change in technology has not been matched by the development of either reliable and standardised design methods or design criteria against which the systems may be evaluated. This paper presents the results of several surveys of daylight guidance systems in 13 working buildings. These give an indication of the conditions created, which are used as the bases of suggested design criteria. A critical review of existing performance prediction methods notes that these lag far behind comparable methods for electric lighting and conventional glazing. A number of improved methods of prediction, currently under consideration by the CIE Technical Committee TC3-38, are presented and each is tested against measured data from the installation surveys.