An Accurate Prediction of Daylight Pipe Harvesting of Interior Space

Abstract

Featured Application: The results of this research are useful in correct assessment of daylighting quality in the interiors respecting the typical instability of sky states. The computations we have performed allow for designing the optimum energy-saving solutions for light-pipe systems. Abstract:The performance of a light guide under arbitrary meteorological conditions is difficult to predict numerically because none of the present methods can account for the random configuration of clouds. Although, partly cloudy skies typically occur very frequently in many regions over the globe, the effects of cloud sizes, distributions, or altitudes on the luminous effectiveness of a light guide remain virtually unknown. The physical installation of light guides does not allow for a controlled experiment in which a single parameter can be varied within a defined range, while holding all other parameters constant. Numerical modeling is the only practical way to provide deep insights on the role of a specific property, such as cloud coverage, and its importance relative to all others (e.g., atmospheric turbidity). We have developed a unique solution through linking the UniSky simulator and HOLIGILM (hollow light guide interior illumination method) tool, while providing for the first time a powerful method that can provide accurate predictions and understanding of the fundamental differences of light guide behaviors under homogeneous and inhomogeneous sky states. The use of homogeneous skies in low-accuracy empirical models often results in overestimated/underestimated effectiveness of some light-guide systems. The model we have developed can predict complex optical signatures that are normally impossible to reproduce using up-to date empirical models (e.g., the illuminance patterns due to isolated clouds or clouds traversing across the sky). The optical efficiency, average cosine and working-place illuminance are analyzed and compared in order to demonstrate the model capabilities.

Investigation of the Efficacy of Horizontal Hollow Light Tubes for Energy Conservation in Illuminating Buildings

“…Any departure from perpendicularity reduces the effective collection area, leading to decreased light intake and potential losses, as light may escape the system. This consideration becomes particularly important when factoring in the varying position of the light source [29][30][31][32][33][34][35][36]. These findings indicate a common decrease in illuminance at the upper and lower termini of both types of tubes in response to an increase in the incident elevation angle of the light source.…”

“…The angle theory explores factors like incidence, reflection, total internal reflection, tube length, diffuser design, and building orientation, influencing system efficiency. Understanding the angles of light during design is crucial, as it leads to optimal performance, promoting energy conservation and improved indoor environments [31][32][33][34][35][36].…”

“…This aligns with sustainable building practices by minimizing energy consumption, enhancing aesthetics, and supporting sustainability goals. Design optimization through angle considerations contributes to better performance, energy conservation, and improved indoor environments [31][32][33][34][35][36]. Related concepts include lighting power density (LPD) and normalized power density (NPD), key metrics in energy-efficient building design [41][42][43][44][45].…”

A Review on Effective Use of Daylight Harvesting Using Intelligent Lighting Control Systems for Sustainable Office Buildings in India

“…This analytical model can be easily integrated into ray-tracing programs such as Radiance which can further be used to predict daylight due to direct radiation [66]. The problem and the only practical way to gain deep insight into complex shifts of the cloud is by computational simulation [67]. Hence ref.…”

“…Hence ref. [67] developed a model using the UniSky simulator and HOLIGILM tool, which provides accurate predictions of fundamental variations of light guide behavior under homogeneous and non-homogeneous cloud conditions. Natural light can be delivered into a light guide system.…”