Solar-Tracking Daytime Lighting Systems Spreading among Households

Advanced daytime lighting systems, which have so far been used mainly in offices and public facilities, are attracting the attention of Japanese people who want to enjoy comfortable natural sunlight in their homes. This is becoming more possible as smaller, lighter daytime lighting system models are becoming available.

These systems automatically track the sun, and transmit the sunlight to spaces where there is limited natural light, such as basements or rooms where the sunlight is blocked by high-rise buildings. The Sunlight System Association, an industry organization, reports that about 6,000 units have been sold in Japan since they became commercially available about a decade ago. In 2004, sales increased 10 percent over the previous year to 700 units, about half of which were for residential use.

The "Himawari" (sunflower), a system developed by Laforet Engineering Co., gathers sunlight with high-performance convex lenses and transmits it into rooms or basements through optical fiber cables. Its sunlight collector is installed outdoors and catches sunlight efficiently with an automated sun tracking system. To provide quality sunlight, the collector cuts off ultraviolet and infrared rays by using a chromatic aberration effect that causes focal points in a lens to vary according to the wavelength of light.

In addition to the energy-saving benefits of using sunlight, these systems require almost no maintenance costs. Some challenges remain, for example, their relatively high price and variable brightness depending on the time of day and weather.



Posted: 2005/06/22 09:58:42 AM
Japanese version