Shielding angle

The shielding angle – both the upper and the lower – is a crucial factor for visual comfort and the prevention of glare. The correct selection and adherence to the shielding angles defined by DIN EN 12464-1 and DIN EN 12665, in conjunction with appropriate technical measures such as diffusers, louvers, or special reflectors, helps ensure glare-free light and optimize visual performance. Manufacturers and planners must ensure that the luminaires used comply with both glare reduction requirements and safety standards.

Upper Shielding Angle:

The upper shielding angle refers to the angle between the horizontal plane and the line of sight, under which the luminous parts of the light source in a luminaire become just visible. This angle is crucial for limiting glare from direct view of the luminaire. DIN EN 12464-1 defines this angle and ensures that light sources are optimally shielded under this angle to prevent glare. Especially for luminaires with high luminance, such as LED lights, it is important to maintain a sufficient upper shielding angle to limit the directly visible luminance.

Minimum Shielding Angle according to DIN EN 12464-1

Luminance [kcd/m²]	Minimum Shielding Angle [α]
20 to < 50	15°
50 to < 500	20°
≥ 500	30°

Visualisation of the upper shielding angle

Lower Shielding Angle:

The lower shielding angle is defined by DIN EN 12665 as the angle between a vertical line through the light source and the direction from which the light source is just no longer visible. This angle is especially important for downlights with high luminance. Here, it is essential to ensure that the light source is not directly visible from unwanted viewing angles to avoid glare. One solution for this is the use of darklight reflectors, where the light source is deeply recessed into a reflector, preventing direct visibility.

The UGR Method:

The prevention of glare is not only ensured by the correct shielding angle but also by adhering to UGR (Unified Glare Rating) values. The UGR method evaluates the average luminance in the direction of the observer. However, glare effects can still occur with positive UGR values if luminaires are insufficiently shielded, especially when the light sources or their components are directly visible from critical viewing angles. For LED luminaires, which often have very high luminance, special requirements apply. Since their point light sources can cause intense glare, appropriate measures such as diffusers, lenses, or prismatic covers must be used to diffuse the luminance and minimize glare. Additionally, manufacturers must comply with the requirements of EN 60598-1 regarding photobiological safety to ensure that the luminaires used do not pose health risks. Back