[Column] Residential Area to Open with Streets Illuminated Only by LED Lights

Oct 23, 2008 21:02 Satoshi Ookubo, Nikkei Electronics

Streets illuminated using only LED lights.

This concept will become a reality before long. A residential subdivision using LED lamps for exterior illumination will open Oct 25, 2008.

The residential zone, "Azabu no Oka," is located in Miyoshicho, Aichi Prefecture, Japan, and developed by Toyota Smile Life Inc. The roads and pathways in the zone, which has 204 housing plots, will be illuminated by LED lamps, according to the company. It will take some time before the entire subdivision is completed, but LED lamps have been used since the start of the project.

I had an opportunity to listen to a lecture by Tsutomu Ochiai, head of M&O Design Office, who worked out plans and designs for illuminating this subdivision, at a training session given the other day for the members of the LED Lighting Association. I got a glimpse of the streets illuminated using LED lamps through this lecture.

Speaking of exterior LED illumination, we imagine LED street lamps lined up along a street. But the illumination adopted by Azabu no Oka is a little different. The zone will be illuminated by LED lamps located in each residential site and a small number of LED street lamps, Ochiai said.

Each of the houses has four to five LED exterior lamps, and they illuminate the roads and pathways as well as exterior walls of each house. The LED street lamps are installed only at the intersections of main roads inside the subdivision. This was designed so as to "foster a sense of unity among the residents by illuminating common areas using just the lights from each house," Ochiai said.

The LEDs (manufactured by Toyoda Gosei Co Ltd) have the color of a regular bulb, creating a warm feel. Each of the lamps is not very bright, but the perceived brightness seems to be greater than what it actually is because the lamps are positioned in various locations, he said.

Light cast on vertical walls increases the perceived brightness, Ochiai said. These lighting concepts are applicable to existing light sources, but LED lights make a difference with a power consumption that is about 1/4 of existing light sources.

The concept has many other features. One is that lights are directed only to areas that need to be illuminated. To illuminate pathways, for example, only walking areas are illuminated, minimizing lighting cast on plants along the pathways. This is to prevent night-time illumination from affecting the ecosystem.

The illumination design took advantage of LED lamps, which have high directivity and are suitable for lighting a limited area. Some people say that LED lamps are not suitable for illumination because of this high directivity. They might say that such luminance is efficient for floors and desktops, but walls that are not directly illuminated remain dark because there is no light leakage, giving the impression that the entire room is dark.

However, from the viewpoint of the ecosystem, this claim does not seem to be reasonable.

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