The total interior lighting
power allowance (watts) for an entire building shall be determined according to
Table C405.4.2(1) using the Building Area Method, or Table C405.4.2(2) using
the Space-by-Space Method. The interior lighting power allowance for projects
that involve only portions of a building shall be determined according to Table
C405.4.2(2) using the Space-by-Space Method. Buildings with unfinished spaces
shall use the Space-by-Space Method.
C405.4.2.1
Building area method.
For the Building Area Method, the interior lighting power allowance is
calculated as follows:
1. For each building
area type inside the building, determine the applicable building area type and
the allowed lighting power density for that type from Table C405.4.2(1). For
building area types not listed, select the building area type that most closely
represents the use of that area. For the purposes of this method, an "area"
shall be defined as all contiguous spaces that accommodate or are associated
with a single building area type.
2. Determine the floor area for each building
area type listed in Table C405.4.2(1) and multiply this area by the applicable
value from Table C405.4.2(1) to determine the lighting power (watts) for each
building area type.
3. The total
interior lighting power allowance (watts) for the entire building is the sum of
the lighting power from each building area type.
C405.4.2.2
Space-by-Space
Method. Where a building has a space designated as unfinished, neither
the area nor the lighting power in the space shall be calculated as part of the
LPA. For the Space-by-Space Method, the interior lighting power allowance is
calculated as follows:
1. For each area
enclosed by partitions that are not less than 80 percent of the ceiling height
determine the applicable space type from Table C405.4.2(2). For space types not
listed, select the space type that most closely represents the proposed use of
the space. Where a space has multiple functions, that space shall be broken up
into smaller subspaces, each using their own space type. If an entire space has
multiple functions that necessitate a higher lighting power allowance in order
to serve one of the primary functions, the higher allowance is permitted to be
used.
2. Determine the total floor
area of all of the spaces of each space type and multiply by the value for the
space type in Table C405.4.2(2) to determine the lighting power (watts) for
each space type.
3. The total
interior lighting power allowance (watts) shall be the sum of the lighting
power allowances for all space types.
C405.4.2.2.1
Additional interior
lighting power. Where using the Space-by-Space Method, an increase in
the interior lighting power allowance is permitted for specific lighting
functions. Additional power shall be permitted only where the specified
lighting is installed in addition to and automatically controlled separately
from
general lighting, in accordance with Section C405.2.6.
This additional power shall be used only for the specified luminaires and shall
not be used for any other purpose.
An increase in the interior lighting power allowance is
permitted for lighting equipment to be installed in sales areas specifically to
highlight merchandise. The additional lighting power shall be determined in
accordance with Equation 4-14.
(Equation 4-14)
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EXCEPTION:
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Other merchandise categories are permitted to be
included in Retail Areas 2 through 4, provided that justification documenting
the need for additional lighting power based on visual inspection, contrast, or
other critical display requirement is approved by the code
official.
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