Abstract
This paper presents the first comparative study of its type of the performance of light pipes with different types of apertures: a flat glass versus a bohemian crystal dome. Measurements were taken at 20-minute intervals over a period of one year in the bathrooms of two newly built identical houses of the same orientation located in Manchester, UK. The comparative analysis of the data collected for both light pipes types reveals that the crystal domed aperture consistently outperforms the flat glass one. Furthermore, the difference in the recorded horizontal illuminance is most marked during the winter months and at the end of the one-year experiment, indicating that the crystal dome has better performance for low incident winter light and higher resistance for the long term effect of weathering and pollution. This study provides strong evidence based on long term real measurements. Such evidence informs architects’ decisions when weighing up the aesthetic considerations of a flat glass aperture versus the higher illumination levels afforded by a crystal dome aperture with higher resistance to weathering and pollution.
Highlights
Daylight illumination is the preferred method of getting light into buildings
The increasing interest in light pipes for introducing natural light in built spaces has led researchers to propose different methodologies and models to foresee indoor illuminances and compare different solutions [5,6,7,8]. This interest has taken into account the different climatic conditions around the world and the interest in the use of light pipes in buildings
Besides habitable built indoor spaces, light pipes have been used to light other critical infrastructure spaces such as road tunnels, where they have been implemented either as standalone installations [10] or coupled with heliostats [11] and even fully with optical fibres [12]. Their use in tunnels is justified because lighting during the daytime of road tunnels is very expensive due to the long time needed by the human eye for light to dark adaptation
Summary
Daylight illumination is the preferred method of getting light into buildings. This is usually accomplished by the use of windows placed in the façade walls. Known as Tubular Daylight Guidance Systems (TDGS), were developed in the early 1990s as a solution to bring daylight from the roof or façades of a building into its deep windowless spaces [1,2,3,4]. They have been proven to be an environmentally friendly and healthier substitution for electric lighting of windowless spaces during daylight hours. It provides an original contribution to knowledge based on understanding the performance of the two light pipes over a period of one year, allowing an understanding of their real performance under different sky conditions and throughout the four seasons of a full year
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