The Unified Glare Rating (UGR) is a measure of lighting efficiency and glare visibility in a space. It's an index used to assess how individuals experience lighting in terms of glare and comfort .
The UGR index is used to measure the amount of lighting that causes glare (indirect light scattering) or lighting interference , which can lead to unpleasant experiences for people in the space.
UGR score:
- The UGR score is a number between 10 and 30+ , where:
- UGR below 19 is considered comfortable (ideal for workspaces, offices, reading environments).
- UGR between 19 and 22 may be acceptable for standard use, such as in commercial spaces.
- UGR above 22 may cause discomfort due to noticeable glare which negatively affects visual performance.
Application of UGR:
- Offices : UGR is used to ensure that the lighting in an office does not cause annoying glare that hinders work.
- Hospitals and Clinics : Glare can be difficult to tolerate in medical environments, especially when people are working under surgical or diagnostic lighting.
- Schools and libraries : Because prolonged exposure to bright lights with high UGR scores can affect work performance, a low UGR is important for concentration and well-being.
How is UGR calculated?
UGR is calculated based on several factors, such as:
- The brightness of the light sources in a room.
- The distance of the light sources from the observer.
- The position of the light in relation to the direction of view.
- The reflections of surfaces (such as walls, desks) in space.
A lower UGR score means less glare, resulting in a more pleasant and comfortable working environment.
Summary:
The UGR (Unified Glare Rating) is a measure of the amount of glare experienced in a room due to lighting. It ensures that lighting is comfortable and does not cause visual distraction or discomfort. It is widely used in workspaces and other places where prolonged illumination is required, and it helps to ensure an efficient and comfortable work environment .