Lighting can make a huge contribution to the overall look and feel of a room. A key factor is how the ceiling reflects and diffuses the light. To create a pleasant interior the ceiling should be the lightest surface in the room - a white ceiling will reflect more light than a darker one. The lighting itself should not cause glare or surface reflection. This can be avoided by the installation of indirect lighting.
When a ceiling gives good light reflectance and light diffusion, the need for installed lighting is reduced. This results in improved energy efficiency and a better working environment.
Light coloured ceilings make pleasant interiors
Ceilings with high light reflectance give cost-effective lighting
Avoid glare and irritating reflections by using indirect lighting
Light reflectance is expressed as a percentage and states how much of the light falling on a surface is reflected back.
In order to get the best efficiency, both for incident daylight and lighting, the ceiling's light reflectance should be high. High light reflectance also reduces the risk of glare from light fittings, because this in turn reduces the luminance ratio (i.e. the difference in brightness between the light fittings' luminous surfaces and the ceiling). In the case of direct lighting the suspended ceiling's light reflectance should be at least 70%.
With indirect lighting, light reflectance needs to be higher, because the level of illumination in the room then depends largely on how much light the ceiling surface reflects. For satisfactory indirect lighting, the ceiling surface requires a light reflectance of at least 80%.
Ceilings with high light reflectance also lead to cost-effective lighting, particularly when combined with indirect lighting. The diagram shows, in a situation with 100% uplight, how the illuminance from a certain luminaire in a room varies depending on the light reflectance of the ceiling.
Illuminance from a certain luminaire in a room with 100% uplight
1. Illuminance (lux)
2. Akutex T white 010 (84%)
3. Akutex T yellow 364 (81%)
4. Akutex T light grey 965 (65%)
5. Akutex T medium grey 966 (49%)
6. Ceiling surface (light reflectance)
Light reflectance is measured in accordance with the CIE Publication No. 15.2 (1986). Measurement values are evaluated with CIE 10 degree Standard Observer (1964) and CIE Standard Illuminant D65.
Light reflectance of Ecophon tiles
Light diffusion (how light is spread) can significantly decrease dazzle and glare from the different surfaces and objects in a room. The more diffusely and evenly the light is spread the better dazzle and glare are prevented. Light diffusion can be defined as the ratio of the diffused reflected light to the totally reflected light. According to DIN 5036 measurements, Ecophon´s ceiling tiles in light colours provide over 99% light diffusion, which means that practically all reflected light can be regarded as diffuse.
1. Reflection from a bright polished metal surface or a mirror.
2. Reflection from an ordinary painted surface causes glare at certain angles.
3. Diffused reflection from the Ecophon Akutex T surface prevents glare and dazzle.
Another way to describe a surface is to measure "gloss". This value is always related to a certain angle (e.g. 20°, 60° or 85°) and does not describe how evenly the reflected light is distributed in space. The gloss value is between 0 and 100, where <10 is low gloss, 10-70 is semi gloss and >70 is high gloss, according to most of the relevant standards, i.e. ISO 2813, ASTM D 523 and DIN 67530.
The gloss of the Ecophon tiles is low, <5, measured at 85°. The gloss of the Connect grids is also relatively low, 20 for white 010 and 4 for Ultra matt black, both measured at 60°.