ASHRAE Journal - September 2023 - 46

TECHNICAL FEATURE
FIGURE 1 Parking garage daylight transition zone, Natick, Mass.
Exterior Lighting Power
Multiple changes were made to exterior lighting
requirements in Table 9.4.2-2 (addendum am). First,
a column was added to the table directly stating which
exterior lighting control(s) apply to each exterior
application. This change improved the clarity of the
code because no changes were made to the existing
exterior lighting control requirements.
Addendum am also reduced the exterior lighting
This power rating change does not directly save
energy. The power requirements save energy. This
power rating in track was necessary to reflect the
change in technology. This change to line-voltage track
allows for track projects to meet these new reduced
lighting power requirements in the prescriptive
sections.
Lighting Exceptions
Additional lighting power exceptions were added
to the existing list in Section 9. Some equipment is
not included within the power calculations when
determining the lighting power allowance for a site
(Section 9.2.2.1). Table 9.2.2.1 lists the equipment
that is exempted and the required lighting controls.
Standard 90.1-2022 recognized germicidal luminaires.
If a luminaire uses light or ultraviolet light for
germicidal function to disinfect spaces, the power for
the germicidal function does not need to be included
in the lighting power budget calculations. Note that
in a dual-function luminaire (e.g., general lighting
and UVC lighting), only the power for the germicidal
function is exempt.
Addendum ac also removed the previous
exception for lighting in casinos and the
daylight transition zone in parking garages
(Figure 1) because new lighting power
requirements for both casinos as well as the
daylight transition zone in parking garages were
added into Standard 90.1-2022.
46
ASHRAE JOURNAL ashrae.org S E PTEM B ER 2023
power values by close to 30%. The values in this table
had not been modified since the 2016 version during
which time LED products have improved and design
practices have changed.
Table 1 includes a sample of these new exterior
lighting power density values from Standard
90.1-2022. Within the standard, exterior lighting is
based on zones. The zones range from Zone 0 (national
park and should be dark) to Zone 4 (major urban
commercial core like Times Square or Las Vegas Strip).
Values in Table 1 are for Zone 3. All the values in the
exterior lighting table changed in similar proportions
as shown in Table 1.
The exterior area, stairway, was removed from Table
9.4.2-2 because it was deemed hard to define in terms
of what the area actually is to be illuminated, i.e.,
is it the stair treads only, the area before and after
the stairs, etc. Exempting the area addressed the
compliance issues at hand.
Guest Room Controls
Standard 90.1 now requires all lighting and switched
receptacles in guest rooms and suites in hotels,
motels, boarding houses and/or similar buildings to
be automatically controlled and turned off after 20
minutes of the space becoming unoccupied (Section
9.4.1.3). Previously the standard allowed spaces with
key card controls to be exempt. Standard 90.1-2022
removed the exception for key cards and explicitly
stated that card key controls could not be used to
TABLE 1 Sample exterior lighting power density values, Standards 90.1-2016, 2019, and 2023.
EXTERIOR AREAS (ZONE 3)
Parking Areas
90.1-2016,
W/ft2
Sales Canopy
Open Outdoor Sales
Loading Docks
0.06
0.60
0.20
0.35
90.1-2019,
W/ft2
0.06
0.60
0.20
0.35
90.1-2023,
W/ft2
0.037
0.50
0.180
0.260
MICHAEL MYER
http://www.ashrae.org
ASHRAE Journal - September 2023

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