In indoor lighting design, how to control the UGR value through the design of the lamp itself

In modern interior lighting design, lighting quality is no longer limited to brightness. The Unified Glare Ratio (UGR) has become a key metric for assessing lighting comfort. Excessively high UGR values ​​can cause eye discomfort, fatigue, and even affect work efficiency. Professional lighting designers pay special attention to the UGR performance of luminaires.

Why Luminaire Design is Key to Controlling UGR
UGR is a complex formula that takes into account multiple factors, including light source brightness, background brightness, human viewing angle, and the number of luminaires. While lighting layout can influence UGR, the design of the luminaire itself, particularly its optical system, is the decisive factor. A luminaire designed from the outset for low glare will perform well in any layout.

Light Source Brightness: Light source brightness is the core source of glare. LED light sources are inherently high-brightness point sources. If left untreated, they can produce strong glare when directly exposed to the eye.

Luminous Area: Increasing the luminous area can effectively reduce the brightness per unit area, thereby reducing glare.

Shade Angle: By controlling the luminaire's shade angle, high-brightness light sources can be hidden from the normal human field of view. Therefore, to fundamentally reduce UGR, it's crucial to address three key aspects: the luminaire's optical materials, structural design, and integration technology.

Optical Material Selection and Application
Appropriate optical materials are the first critical step in achieving low UGR.

Diffusers: High-quality PMMA or PC diffusers are the most commonly used method for reducing glare. They evenly diffuse light from point-source LED sources, transforming high-brightness point sources into soft, surface-based sources. Excellent diffusers not only offer high light transmittance but also effectively blur the grain of LED light, significantly reducing UGR. Some high-performance microprismatic diffusers, with their specialized surface structure, redirect light, further reducing direct glare.

Microprismatic and Light Guide Plates: Some high-end LED panel lights or bracket lights utilize a combination of light guide plates and microprismatic plates. The light guide plate evenly directs light from edge-entry LEDs, while the microprisms on its surface direct the light at a specific angle, effectively attenuating light intensity within the human eye's normal field of view of 20-60 degrees. This design achieves precise light distribution while keeping the UGR value to an extremely low level.

Structural Design: The Art of Shading and Reflection
Structural design is key to physically controlling the light path and thus achieving low glare.

Deeply Concealed Structure: The LED light source is hidden deep within the luminaire, creating a deep shading angle. When viewed from a normal angle, the bright LED chip is invisible, instead visible are the relatively soft reflective surface within the luminaire. This design is particularly common in grille lights or downlights, effectively preventing direct glare.

Highly Reflective Grille: In traditional grille bracket lights, a highly reflective aluminum grille precisely controls the direction of light, directing it to the work surface while blocking high-angle glare. Excellent grille design not only provides high reflectivity, but its frosted or polished surface further reduces specular glare from the grille itself.

Reflector Design: In bracket lights, a reflector with a specific curvature can redistribute light. By precisely calculating the reflector's curvature, the majority of light is directed downward, concentrating it on the work area while minimizing upward or high-angle light spillage, fundamentally reducing the energy that could cause glare.

Integrated Technology: The Combination of Light Engines and Optical Modules
Modern LED fixtures are no longer simply a combination of LEDs and drivers. Integrated optical modules are an effective way to reduce UGR.

Optical Modules: Some high-end products integrate the LED chip, reflector, diffuser, and heat sink into a single light engine module. This integrated design enables more compact and precise optical control. For example, LED chips are directly packaged on a lens with a microprism structure, forming a secondary optical lens that controls light distribution at the source, effectively preventing glare.

Chip Arrangement and Spacing: Proper LED chip arrangement and spacing are also crucial. Overly densely packed chips can create high-brightness hotspots, increasing the risk of glare. By distributing the chips and incorporating a diffuser material, a more uniform and softer light source can be created. Driver and dimming technology: High-quality flicker-free drivers not only improve lighting quality, but their smooth dimming curves also ensure stable light output at any brightness, avoiding visual fatigue caused by low-brightness flickering and indirectly improving comfort.