Visual studies have indicated that the required luminances,
categorized by type of task are as follows (assuming good contrast):
|
|
|||||
| Category of Visual Task | Required Luminance (fL) | ||||
|
|
|||||
| Casual Ordinary Moderate Difficult Severe |
3-6 6-30 30-60 60-120 Above 120 |
||||
|
|
|||||
For the purposes of this case study, the categories of Casual and Ordinary
tasks are of the greatest relevance for the Museum setting. These numbers
represent the amount of light in foot candles that is required to have visual
comfort doing a certain task. This information informs us that while
in a museum a viewer will need between 3-30 fL of light to have
visual comfort.
Reference: Mechanical and Electrical Equipment for Building; Chapter 18; pages 937-938.