Quality Characteristics for Lighting

There are specific quality criteria that indicate what must be taken into account for high-quality lighting. The classic quality criteria for lighting can be divided into three main categories: visual comfort, visual performance, and visual ambiance. These are broken down as follows:

Visual comfort:

• True-to-life color rendering for accurate color differentiation, as indicated by the color rendering index (CRI or RA)
• Harmonious brightness distribution achieved through a balanced ratio of luminance levels

Visual Acuity:

• Illumination level for sufficient brightness, expressed in lumens (lm)
• Glare limitation for comfortable vision without reflected or direct glare, particularly important in workplaces; indicated by the UGR value

Visual Ambience:

• Shading for Identifying Surface Structures
• Light color in Kelvin for the right room ambiance and color recognition
• Light Direction for Lighting Control

If all these quality characteristics are taken into account and a light fixture sufficiently meets them, it can be assumed that the fixture is of very good quality. For individual characteristics, such as light color, there is no “good” or “bad”—rather, it is a matter of whether it is suitable for the situation or not. This also applies, among other things, to the luminaire’s brightness and light distribution. Additionally, other criteria—such as energy efficiency or specific adjustment options—can be taken into account during lighting design.