Hikari Dental Clinic, Japan

This project involves a unique dental clinic featuring a column-free space with a ceiling height of up to 5 meters. Our lighting design not only creates gentle, human-centered lighting for both staff and patients using a minimal quantity of fixtures but also elevates light to the core essence that enhances the quality of spatial experience, demonstrating the power of lighting from both scientific and artistic perspectives.

The building, originally a local bank branch built over 50 years ago, was converted into a dental clinic while preserving its column-free space. The central area contains two lower spaces (laboratory and X-ray room), surrounded by treatment rooms. The corridors connecting these spaces are angled to maintain patient privacy without doors, while their irregular shapes and limited sightlines create an experience reminiscent of walking through narrow alleyways.

The largest opening faces north, with no openings on the south or west sides. Linear lights are installed above the ceilings of the two lower spaces (four above the larger and two above the smaller) to provide ambient indirect illumination throughout the space. Their height is carefully adjusted to remain unseen and to eliminate cutoff lines caused by the raised volumes.

Narrow-beam Φ75mm adjustable downlights are placed only at spatial transitions, eliminating the presence of fixtures while illuminating the floor. These light pools guide pedestrians along the angled corridors toward the intended treatment rooms. Reflected light on walls, floors, and ceilings transforms lighting from a functional element into an experience that influences perception and emotion.

The waiting area facing north receives abundant natural light through glass blocks. Lighting calculations including daylight were conducted to determine the minimum required levels and fixture counts. A lighting cove above the opening uses the same fixtures as the linear lights above the lower spaces, providing supplementary illumination that brightens the entire waiting area and the sloped ceiling where daylight is limited.

Treatment rooms are equipped with high-CRI (Ra90+) downlights on the ceiling and indirect lighting above and below shelving to support precise color judgment and detailed dental work. This ensures uniform illumination without glare while minimizing shadows.

Linear lights in the central area are tunable between 2700K and 20000K (Azure light). Before opening, the Azure light promotes staff alertness; during operation, 3500K balances concentration and calm; after hours, 2700K creates a soothing environment. These transitions occur over five minutes, conveying time naturally without relying on clocks. The Azure light also recreates an open sky on the ceiling and generates an immersive “Blue Cave” experience along the angled corridors, with reflected oceanic blue creating depth and a sense of enclosure.

This project is the first in Japan to use spectrally controlled Azure light, scientifically proven to influence circadian rhythms, in a medical space. The human-centric circadian lighting model established here has potential applications beyond healthcare, setting new standards for next-generation lighting design.