This chapter of the nonresidential compliance manual addresses solar-ready
requirements for hotels/motels, nonresidential, and high-rise multifamily
buildings. These requirements are in §110.10|topic=SECTION 110.10 – MANDATORY REQUIREMENTS FOR SOLAR
READINESS and §141.0
and are mandatory for newly constructed buildings and additions where the total
roof area is
increased by at least 2,000 square feet.
The solar-ready requirement is
implemented when designing the building rooftop and associated equipment. The intent is to reserve
a penetration-free and shade-free portion of the roof for the potential future
installation of a solar energy system. There are no requirements to install
panels, conduit, piping, or mounting hardware.
The solar-ready
provisions are mandatory; “trade-offs” are not allowed. There are exceptions to
the “solar zone”
requirements, and these are described in the corresponding sections of this
chapter. Because solar ready is mandatory, the NRCC-SRA-E compliance form must
be submitted with the building permit application, even when using an allowable solar
zone exception.
§110.10(a)
The nonresidential solar-ready
requirements apply to:
• Hotel/motel
occupancies with 10 stories or fewer.
• All
other nonresidential buildings with three stories or fewer.
• See
Example 9-15
Mixed-Occupancy Buildings: The Energy
Standards apply to mixed-occupancy buildings. Buildings with nonresidential
space on the ground floor and multifamily residential floors above are common
examples.
§110.10(b)|topic=(b) Solar
Zone.
The solar zone is a suitable place where
solar panels can be installed at a future date if the owner chooses to do so. A
solar zone area is designed with no penetrations, obstructions, or significant
shade. The solar zone must comply with the access, pathway, smoke ventilation,
and spacing requirements in Title 24, Part 9. Requirements from the other parts
of Title 24 and those adopted by a local jurisdiction should also be
incorporated in the solar zone design.
The solar zone can be located at
any of the following locations:
• Roof of building
• Overhang of the
building
•
Covered parking installed with the building project
• Roof
of another structure located within 250 feet (75 meters) of the primary
building
•
Overhang of another structure within 250 feet (75 meters) of the primary
building
Other structures include, but are
not limited to, trellises, arbors, patio covers, carports, gazebos, and similar
accessory structures.
Multifamily Buildings: Solar-ready
requirements for low-rise and high-rise multifamily buildings are in Chapter 11
of the Nonresidential Compliance Manual. In the 2022 Energy Standards,
the solar zone requirements for low-rise multifamily buildings are grouped with
high-rise multifamily, hotel/motel and nonresidential in §110.10(b)1B|topic=(b) Solar
Zone..
§110.10(b)1|topic=(b) Solar
Zone.
Total Area:
The solar zone
must have a total area of at least 15 percent of the total roof area, after subtracting any
skylights. See Example 9-16.
Multiple
areas: The solar zone may be composed of multiple subareas if they meet the
following minimum size specifications:
1.
Each subarea dimension must be at least 5 feet.
2.
If the total roof area is equal to or less than 10,000 square feet, each subarea
must be at least 80 square feet.
3.
If the total roof area is greater than 10,000 square feet, each subarea must be
at least 160 square feet.
Example 9-14:
Question:
A
roof with no skylights has an area of 10,000 sq. ft. A neighboring building shades the
roof, so 7,500 sq. ft of the roof has less than 70 percent annual solar access.
How big does the solar zone have to be?
Answer:
If
the entire roof had an annual solar access of 70 percent or greater, the minimum
solar zone would be 1,500 sq. ft, or 15 percent of the total roof area (10,000
sq. ft.). However, since the potential solar zone is 2,500 sq. ft, the minimum
solar zone can be reduced to half the area of the potential solar zone, or 1,250
sq. ft.
Example 9-15:
Question:
The
total roof area is less than 10,000 sq. ft., but the potential solar zone is
less than the minimum size requirements for any subarea (less than 80 sq. ft. or
narrower than 5 feet in the smallest dimension). Does the building still need to
comply with the solar-ready requirements?
Answer:
No.
If half the potential solar zone is less than 80 sq. ft. (if roof is less than
or equal to 10,000 sq. ft) or 160 sq. ft. (if roof is greater than 10,000 sq.
ft), then the building does not need to comply with the solar zone
requirements.
Example 9-16:
Question:
A
portion of an office building will have six stories, and a portion of the
building will have two stories. Is the new building subject to the solar zone
requirements?
Answer:
No,
the solar-ready requirements do not apply to office buildings that have more
than three stories. The solar-ready requirements apply only to hotel/motel
occupancies and high-rise multifamily buildings with 10 or fewer stories and all
other nonresidential buildings with 3 or fewer stories.
Example 9-17:
Question:
A
new warehouse
has a total roof area of 80,000 sq. ft. Skylights cover 2,560 sq. ft. of the
total roof area. What is the minimum solar zone area?
Answer:
The minimum solar zone area would be 11,616 sq.
ft
Example 9--18:
Question:
Does
the solar zone have to be one contiguous area?
Answer:
No,
the solar zone does not have to be one contiguous area. The total solar zone can
be composed of multiple smaller areas. A subarea cannot be narrower than 5 feet
in any dimension. If the total roof area is 10,000 sq. ft or less, each subarea
must be at least 80 sq. ft. If the total roof area is greater than 10,000 sq.
ft, each subarea must be at least 160 sq. ft.
The
image below illustrates a solar zone layout that is composed of eight smaller
subareas. The sum of all the smaller areas must equal the minimum total solar
zone area. In this case, the sum of all areas must be at least 11,616 sq. ft.
The solar zones must also comply with fire code requirements, including, but not
limited to, setback and pathway requirements. Current fire code requirements can
be found in Title 24 Part 2 § 3111, Title 24 Part 2.5 §R331, and Title 24 Part 9
§ 903.3.
There are five exceptions to the solar zone area
requirement described in §110.10(b)1B|topic=(b) Solar Zone.. Some exceptions are
limited to certain buildings, as noted in the exception details below. Submit an
NRCC-SRA-E, the "Solar Ready Areas" certificate of compliance to the enforcement
agency for all building projects subject to solar ready, even if using a solar
zone exception.
Exception 3 allows a reduced-size
solar zone when solar access is limited by certain circumstances.
Exceptions 1, 2, and 4 allow
alternate efficiency measures instead of a solar zone, so the requirements for
zone shading,
orientation, and design load; interconnection pathway; and owner documentation
do not apply either. Any installations must be inspected and verified prior to
final approval by the enforcement agency.
Exception 1: A compliant solar
electric system is permanently installed on high-rise multifamily, hotel/motel, and
nonresidential buildings. The system must have a nameplate direct current (DC)
power rating of no less than 1 watt per sq. ft of roof area. The nameplate rating must be
measured under standard test conditions. See Example 9-6. To verify compliance
with this exception, submit NRCI-SPV-01-E Certificate of Installation: Solar
Photovoltaic System.
Exception 2: A solar hot water
system (SWH) is permanently installed on high-rise multifamily, hotel/motel, and
nonresidential buildings. The SWH system must comply with §150.1(c)8Biii|topic=8. Domestic
Water-Heating Systems., the prescriptive solar requirements
for a system serving multiple dwelling units. To verify compliance with this exception,
submit NRCI-STH-01-E Certificate of Installation: Solar Water Heating
System.
Exception 3: Reduce the solar zone
area when the roof is shaded by objects that are not part of the building
project, and therefore beyond the designer’s control. The designated solar
zone may be reduced to ≥ 50 percent of the potential solar zone area when solar
access is limited as described below. When the “potential” solar zone is smaller
than the 250 sq. ft minimum, the solar zone can be reduced to half the area of
the potential solar zone. The reduced-size solar zone is called the “designated”
solar zone.
Exception for Reduced Solar
Zone
Step 1: Determine the
annual solar access: For the solar-ready requirements, solar access is the ratio
of solar insolation including shading to the solar insolation without shading.
Annual solar access is most easily determined using specialized software.
Solar access does not take into
account shading from objects that are included in the building project because
the designer has control of potential obstructions. Objects that are not part of
the building project cannot be moved or modified as part of the project and
include existing buildings, telephone poles, communication towers, trees, or
other objects. Objects that are considered part of the building project are
objects constructed as part of the building project and include the building
itself, its HVAC equipment, outdoor lights, landscape features and other similar
objects.
First, evaluate whether there are
any objects outside the building project that will shade the rooftop (or other
prospective solar zone areas such as overhangs or parking shade structures). If
an existing object is located north of all potential solar zones, the object
will not shade the solar zone. Similarly, if the horizontal distance (“D”) from
the object to the solar zone is at least two times the height difference (“H”)
between the highest point of the object and the horizontal projection of the
nearest point of the solar zone, then the object will not shade the solar zone.
(See Figure 9-2.)
Step 2: Determine the
potential solar zone area: On low-sloped roofs, the potential solar zone is the
area where annual solar access is ≥ 70 percent.
On steep-sloped roofs the
potential solar zone is the area where the annual solar access is
≥ 70 percent on the portion
oriented between 90 and 300 degrees of true north.
A “demand-responsive control” is
defined in §100.1. as an “automatic control capable of
receiving and automatically responding to a demand response signal.”
The technical specifications for compliant demand responsive
control thermostats are detailed in JA5.
In addition to the demand-responsive
thermostats, choose Option A or Option B (below).
Each dwelling unit must have one of
the following four measures (1 – 4):
a)
Install a dishwasher that meets or exceeds the ENERGY STAR® program requirements
with either a refrigerator that meets or exceeds the ENERGY STAR program
requirements or a whole-house fan driven by an electronically commutated
motor.
b)
Install a home automation system that complies with §110.12(a)|topic=(a) Demand
responsive controls. and capable of, at a minimum, controlling
the appliances and lighting of the dwelling and responding to demand-response
signals.
c)
Install alternative plumbing piping to permit the discharge from the clothes
washer and all showers and bathtubs to be used for an irrigation system. It must
comply with the California Plumbing Code and local ordinances.
d)
Install a rainwater catchment system that uses rainwater flowing from at least
65 percent of the available roof area. It must comply with the California
Plumbing Code and local ordinances.
Meet the Title 24 Part 11,
Section A4, 106.8.2 requirements for electric vehicle charging spaces.
Exception 5: Applies to
multifamily, hotel/motel, and nonresidential buildings. If the roof is designed
and approved to be a heliport, or used for vehicular traffic or parking, no
solar zone is required. Therefore, interconnection pathway and documentation
requirements do not apply.
9.8.5.1
Solar Zone Azimuth
All sections of the solar zone on
steep-sloped roofs (rise-to-run ratio greater than 2:12, or 10 degrees) must be
oriented between azimuths of 90 degrees and 300 degrees of true north. This
range of azimuths ensures a reasonable solar exposure if a solar energy
system is installed in the future. On a low-sloped roof (rise-to-run ratio equal to or less
than 2:12, or 10 degrees), the azimuth requirement does not apply.
Figure 9-1: Azimuth
of Roof If Solar Zone Is Located on Steep-Sloped Roof
Source: California Energy
Commission
9.8.5.2
Solar Zone Shading
§110.10(b)3|topic=(b) Solar
Zone. Obstructions such as vents, chimneys, architectural
features, or roof-mounted equipment cannot be located in the solar zone. This requirement ensures
the solar zone remains clear and open for the future installation of a solar
energy system.
Any obstruction located on the roof
or any other part of the building that projects above the solar zone must be located at
a sufficient horizontal distance away from the solar zone such that the
obstruction will not shade the solar zone. Equation 9-5 and Figure 9.2 describe
the allowable distance between any obstruction and the solar zone. For each
obstruction, the horizontal distance (“D”) from the obstruction to the solar
zone has to be at least two times the height difference (“H”) between the
highest point of the obstruction and the horizontal projection of the nearest
point of the solar zone.