Benefits of glass fibers in solar fiber optic lighting systems

Abstract

The transmission properties and coupling of solar light have been studied for glass core multimode fibers in order to verify their benefits for a solar fiber optic lighting system. The light transportation distance can be extended from 20 m with plastic fibers to over 100 m with the kind of glass fibers studied here. A high luminous flux, full visible spectrum, as well as an outstanding color rendering index (98) and correlated color temperature similar to the direct sun light outside have been obtained. Thus the outstanding quality of solar light transmitted through these fibers would improve the visibility of all kinds of objects compared to fluorescent and other artificial lighting. Annual relative lighting energy savings of 36% in Uppsala, Sweden, and 76% in Dubai were estimated in an office environment. The absolute savings can be doubled by using glass optical fibers, and are estimated to be in the order of 550 kWh/year in Sweden and 1160 kWh/year in Dubai for one system of only 0.159 m(2) total light collecting area. The savings are dependent on the fiber length, the daily usage time of the interior, the type of artificial lighting substituted, the system light output flux, and the available time of sunny weather at the geographic location.

Daylight Transport Systems for Buildings at High Latitudes

“…It was recorded that light output using SOF was 4200K, Ra 98, while POF had 7000K, and Ra75 light output. Light transmittance on exterior 100 000lux after 20m fiber was 500lux for SOF and 400lux for POF [132]. Liquid core fibers have attenuation coefficients below 2-dB/m across for the visible spectrum, and very low for IR [133].…”

Dual ducting: An innovation to increase the use of daylight in buildings

“…The fibre optics are just a few centimetres in diameter and can thus be routed in buildings in similar way to electric cables. 7,18,19…”

“…[2][3][4][5] The second approach aims to deliver daylight into windowless and remote spaces within buildings via light wells, light pipes or fibre optics. [6][7][8][9] The systems which depend upon this approach are typically called daylight guidance systems (DGS). Although many DGS have been developed over the last few decades, none of them has strongly penetrated the market.…”