Indoor Luminance Recommendations

This procedure is the currently recognized method of the Illuminating Engineering Society of North America to determine the level of maintained illumination needed to perform a specific task. This method considers factors that most commonly contribute to the visual comfort of the various task listed later in this article.  It provides a range of illumination levels for defined task, then specifies a target luminance level from within that range using factors determined through research of lighting performance requirements.

The following conditions are factored into this method:

•   Task to be performed.

•   Detail of the objects to be viewed.

•   Age of the observer.

•   Importance of speed and accuracy for the visual task

•   Reflectance of the background material.

Determining Appropriate Illuminance Levels

Step 1 Determine the type of activity for which the level of lighting is to be selected.

Step 2 Select the appropriate illuminance category by one of the following methods.

When the visual task is defined by one of the typical task categories, choose the appropriate illuminance category from Table A

Specific Task Illuminance Level Guide - Table A

If a specific task cannot be established, the illuminance category may be determined from the generic task description listed in Table B.

Range of Illuminances - Table B

Step 3 Establish illuminance target value. Once the illuminance category is chosen, an exact illuminance level may be determined from within this range. These levels are established on Table C by matching the appropriate user, room, and task characteristics with the previously determined illuminance category.

Illuminance Values - Table C (General Light)

Illuminance Values - Table C (Illuminance on Task)