Although the 2022 Title 24 code came into effect January 1, 2023, the Energy Code Coach service continuously receives inquiries regarding solar and battery requirements for New Construction Nonresidential projects. In prior code cycles, nonresidential buildings had to be photovoltaic (PV) ready; this updated code not only requires PV’s to be installed, but also requires energy storage systems (ESS, aka batteries).
Below, we simplify those requirements.
Since both PV and Batteries are now Prescriptive Requirements, it can be difficult to avoid the inclusion of either system in your project, even if you are using trade-offs in a performance approach. With that in mind, it’s likely better to assume inclusion of both PV’s and batteries from the outset; that way, you can simply determine the required size of each system.
Photovoltaic Requirements
If your project’s occupancy is any of the following spaces, you are required to install a PV system unless the building qualifies for an exception (see section 9.2.2 for a list of exceptions):
- High-Rise Multifamily
- Grocery
- Office, Financial Institutions, Unleased Tenant Space
- Retail
- School
- Warehouse
- Auditorium, Convention Center, Hotel/Motel, Library, Medical Office Building/Clinic, Restaurant, Theater
- Multifamily buildings up to three habitable stories
To determine the size of your required array you’ll use Equation 140.10-A from Section 140.10(a).
CFA = Conditioned floor area in square feet
A = PV Capacity factor specified in Table 140.10-A for each building type by climate zone.
Table 140.10-A – PV Capacity Factors
| Factor A – Minimum PV Capacity (W/ft2 of conditioned floor area) | |||
|---|---|---|---|
| Climate Zone | 1, 3, 5, 16 | 2, 4, 6-14 | 15 |
| Grocery | 2.62 | 2.91 | 3.53 |
| High-Rise Multifamily | 1.82 | 2.21 | 2.77 |
| Office, Financial Institutions, Unleased Tenant Space | 2.59 | 3.13 | 3.80 |
| Retail | 2.62 | 2.91 | 3.53 |
| School | 1.27 | 1.63 | 2.46 |
| Warehouse | 0.39 | 0.44 | 0.58 |
| Auditorium Convention Center, Hotel/Motel, Library, Medical Office Building/Clinic, Restaurant, Theater | 0.39 | 0.44 | 0.58 |
For example, the calculation for a 20,000 SF office building in Santa Barabara (Climate Zone 6) would be:
20,000 x 3.13/1000 = 62.6 kWdc PV
Note: If the building includes more than one of the space types listed, the total PV system capacity for the building is determined by summing the capacities of each space type individually.
Multifamily Projects
For multifamily projects that are three habitable stories or less, the energy code takes into consideration the number of dwelling units and different adjustment factors. For multifamily projects, use Equation 170.2-C.
CFA – Conditioned Floor Area
Ndu = Number of dwelling units
A = CFA adjustment factor from Table 170.2-T
B = Dwelling unit adjustment factor from Table 170.2-T[/vc_column_text][vc_column_text css=”.vc_custom_1707430236636{padding-top: 35px !important;}”]
Table 170.2-T – CFA and Dwelling Unit Adjustment Factors
| Climate Zone | A – CFA | B – Dwelling Units |
| 1 | 0.793 | 1.27 |
| 2 | 0.621 | 1.22 |
| 3 | 0.628 | 1.12 |
| 4 | 0.586 | 1.21 |
| 5 | 0.585 | 1.06 |
| 6 | 0.594 | 1.23 |
| 7 | 0.572 | 1.15 |
| 8 | 0.586 | 1.37 |
| 9 | 0.613 | 1.36 |
| 10 | 0.627 | 1.41 |
| 11 | 0.836 | 1.44 |
| 12 | 0.613 | 1.40 |
| 13 | 0.894 | 1.51 |
| 14 | 0.741 | 1.26 |
| 15 | 1.56 | 1.47 |
| 16 | 0.59 | 1.22 |
Energy Storage Requirements
Another new requirement from the 2022 code is the addition of battery storage for California’s nonresidential new construction projects. This requirement is only applicable to new construction non-residential projects (including High-Rise Residential occupancies). Similar to the PV requirements above, there is an equation used to determine the required battery size. You’ll need to use Equation 9-3 and 9-4 from Section 170.2(h).
Equation 9-3
kWpvdc = PV System capacity required by Section 170.2(g)
B = Battery energy capacity factor from Table 170.2-V for the building type
D = Rated single charge-discharge cycle AC to AC efficiency of the battery system
Equation 9-4]
kWpvdc = PV System capacity required by Section 170.2(g)
C = Battery power capacity specified in Table 170.2-V for the building type
Table 170.2-V – Battery Storage Capacity Factors
| Factor B – Energy Capacity | Factor C – Power Capacity | |
| Storage-to-PV Ratio | Wh/W | W/W |
| Grocery | 1.03 | 0.26 |
| High-Rise Multifamily | 1.03 | 0.26 |
| Office, Financial Institutions, Unleashed Tenant Space | 1.68 | 0.42 |
| Retail | 1.03 | 0.26 |
| School | 1.87 | 0.46 |
| Warehouse | 0.93 | 0.23 |
| Auditorium, Convention Center, Hotel/Motel, Library, Medical Office Building/Clinic, Restaurant, Theater | 0.93 | 0.23 |
For our office building example, the battery calculation would be:
62.6 kWdc x 0.42 = 26.3kWh of battery storage.
Be sure to visit the code sections to consider if your project meets any of the exception criteria, such as Section 140.10 and 170.2.
In conclusion, as the design and building industry gets used to the requirements for PV’s and batteries in new nonresidential projects, they’ll find that the calculations themselves are pretty straightforward.
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