Civil Engineering Reference
In-Depth Information
strain. Lighting design is beyond the scope of this text, but careful at-
tention to the brightness, glare, and quality of light is required for good
lighting.
The Illuminating Engineering Society of North America (IESNA)
established three “groups” and seven categories based on descriptions
of various visual tasks, with recommended levels of light for each task
category.
Group1:OrientationandSimpleVisualTasks
Visual performance is largely unimportant for this level of task.
These tasks are found in public spaces where reading and visual inspec-
tion are only occasionally performed. Parking lots are normally lit to 5
footcandles.
Higher levels are recommended for tasks where visual performance
is occasionally important.
Group2:CommonVisualTasks
Visual performance is important. These tasks are found in commer-
cial, industrial and residential applications. A desktop workspace is nor-
mally lit to 30 to 50 footcandles. Recommended illuminance levels differ
because of the characteristics of the visual task being illuminated. Higher
levels are recommended for visual tasks with critical elements of low con-
trast or small size.
Group3:SpecialVisualTasks
Visual performance is of critical importance. These tasks are very
specialized, including those with very small or very low contrast criti-
cal elements. Recommended illuminance levels should be achieved with
supplementary task lighting. Higher recommended levels are often
achieved by moving the light source closer to the task.
The recommended lighting level for each group and task category is
defined by Table 4-7.
The maintenance staff, using a light meter and regular light fixture
maintenance should be able to respond to and correct lighting deficien-
cies in a facility. If not, a lighting engineer can be consulted.
Noise and Vibration
Vibration from HVAC equipment, piping, and ductwork can be
a source of undesired noise and can contribute to perceived poor IAQ.
Search WWH ::
Custom Search