2025 Energy Code · Climate Zone 9
Title 24 Climate Zone 9: ADU Requirements
What the 2025 California Energy Code's prescriptive package requires for a new detached ADU in Climate Zone 9, and how those requirements change the MEP design.
Where Climate Zone 9 is
Of the California places we cover, 85 are mostly in Climate Zone 9, across 2 counties: Los Angeles County, Ventura County. Together they issued 68,614 ADU building permits from 2021 through 2025. Zones follow ZIP-code boundaries, so we confirm the zone from the project address before running the Title 24 report.
2025 prescriptive requirements for a new detached ADU
For a new detached ADU in Climate Zone 9, the 2025 prescriptive package sets these zone-specific targets.
| Windows | U-factor 0.30 or lower; SHGC 0.23 or lower; total area up to 20% of floor area (west-facing up to 5%) |
|---|---|
| Attic, high-performance option | R-38 ceiling; below roof deck: R-19 |
| Attic, ducts-inside option | R-38 ceiling plus radiant barrier; ducts and air handler in conditioned space |
| Framed walls | Assembly U-factor 0.048 or lower |
| Cool roof | Not required |
| Whole-house fan | Required, 1.5 cfm per sq ft of floor area (units of 500 sq ft or less exempt) |
| Space heating and cooling | Heat pump (other systems through the performance approach) |
| Water heating | Heat pump water heater; units of 500 sq ft or less, or one bedroom or fewer, have simpler options |
| Solar PV | kW = (floor area x 0.613) / 1000 + 1.36; none required under 1.8 kWdc (about 718 sq ft or smaller for a single ADU) |
An attached ADU or a garage conversion is an addition under the Energy Code, not new construction, so it follows the addition requirements instead. Solar PV is not required for additions.
Design temperatures across Climate Zone 9
The zone sets the energy targets, but the HVAC is sized from the local design temperature, and that varies inside a zone. Among the places we cover here, the 1% summer design temperature ranges from 87°F in Beverly Hills to 98°F in Pacoima, and the coldest winter design temperature is 25°F in Canoga Park. That spread is why we run a Manual J for each address instead of using a zone-wide rule of thumb.
Places in Climate Zone 9
| Place | County | Electric utility | ADU permits 2021–25 |
|---|---|---|---|
| Los Angeles | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 52,059 |
| North Hollywood (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 3,130 |
| Glendale | Los Angeles | Glendale Water and Power | 2,945 |
| Van Nuys (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 2,156 |
| Pacoima (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,487 |
| Canoga Park (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,485 |
| Burbank | Los Angeles | Burbank Water and Power | 1,376 |
| Woodland Hills (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,256 |
| Granada Hills (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,206 |
| Reseda (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,168 |
| Encino (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,116 |
| Sylmar (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,081 |
| Northridge (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,049 |
| Winnetka (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 1,002 |
| Chatsworth (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 971 |
| Pasadena | Los Angeles | Pasadena Water and Power | 932 |
| Sherman Oaks (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 915 |
| Sun Valley (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 884 |
| Panorama City (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 817 |
| Tarzana (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 654 |
| Rosemead | Los Angeles | Southern California Edison (SCE) | 600 |
| Alhambra | Los Angeles | Southern California Edison (SCE) | 572 |
| North Hills (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 539 |
| Mission Hills (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 534 |
| Altadena (unincorp.) | Los Angeles | Southern California Edison (SCE) | 517 |
| Baldwin Park | Los Angeles | Southern California Edison (SCE) | 511 |
| West Hills (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 495 |
| El Monte | Los Angeles | Southern California Edison (SCE) | 489 |
| Monterey Park | Los Angeles | Southern California Edison (SCE) | 461 |
| Whittier | Los Angeles | Southern California Edison (SCE) | 427 |
| West Covina | Los Angeles | Southern California Edison (SCE) | 423 |
| Valley Village (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 407 |
| Thousand Oaks | Ventura | Southern California Edison (SCE) | 400 |
| Simi Valley | Ventura | Southern California Edison (SCE) | 397 |
| Arcadia | Los Angeles | Southern California Edison (SCE) | 365 |
| Pico Rivera | Los Angeles | Southern California Edison (SCE) | 355 |
| Studio City (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 354 |
| San Gabriel | Los Angeles | Southern California Edison (SCE) | 328 |
| Temple City | Los Angeles | Southern California Edison (SCE) | 328 |
| San Fernando | Los Angeles | Southern California Edison (SCE) | 295 |
| Walnut | Los Angeles | Southern California Edison (SCE) | 293 |
| Sierra Madre | Los Angeles | Southern California Edison (SCE) | 285 |
| Monrovia | Los Angeles | Southern California Edison (SCE) | 271 |
| Montebello | Los Angeles | Southern California Edison (SCE) | 236 |
| Hacienda Heights (unincorp.) | Los Angeles | Southern California Edison (SCE) | 223 |
| Arleta (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 202 |
| Glendora | Los Angeles | Southern California Edison (SCE) | 193 |
| Diamond Bar | Los Angeles | Southern California Edison (SCE) | 192 |
| South Pasadena | Los Angeles | Southern California Edison (SCE) | 192 |
| Beverly Hills | Los Angeles | Southern California Edison (SCE) | 189 |
| Rowland Heights (unincorp.) | Los Angeles | Southern California Edison (SCE) | 186 |
| La Puente | Los Angeles | Southern California Edison (SCE) | 182 |
| Covina | Los Angeles | Southern California Edison (SCE) | 179 |
| Santa Clarita | Los Angeles | Southern California Edison (SCE) | 175 |
| Agoura Hills | Los Angeles | Southern California Edison (SCE) | 175 |
| Moorpark | Ventura | Southern California Edison (SCE) | 171 |
| Claremont | Los Angeles | Southern California Edison (SCE) | 162 |
| West Hollywood | Los Angeles | Southern California Edison (SCE) | 155 |
| La Cañada Flintridge | Los Angeles | Southern California Edison (SCE) | 145 |
| Azusa | Los Angeles | Azusa Light & Water | 135 |
| Porter Ranch (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 132 |
| San Dimas | Los Angeles | Southern California Edison (SCE) | 119 |
| Duarte | Los Angeles | Southern California Edison (SCE) | 119 |
| Ojai | Ventura | Southern California Edison (SCE) | 109 |
| San Marino | Los Angeles | Southern California Edison (SCE) | 103 |
| Pomona | Los Angeles | Southern California Edison (SCE) | 92 |
| La Mirada | Los Angeles | Southern California Edison (SCE) | 92 |
| Santa Fe Springs | Los Angeles | Southern California Edison (SCE) | 88 |
| South El Monte | Los Angeles | Southern California Edison (SCE) | 78 |
| La Verne | Los Angeles | Southern California Edison (SCE) | 72 |
| Calabasas | Los Angeles | Southern California Edison (SCE) | 60 |
| Canyon Country (Santa Clarita) | Los Angeles | Southern California Edison (SCE) | 51 |
| Fillmore | Ventura | Southern California Edison (SCE) | 47 |
| Sherwood Forest (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 46 |
| Newhall (Santa Clarita) | Los Angeles | Southern California Edison (SCE) | 44 |
| Toluca Lake (Los Angeles) | Los Angeles | Los Angeles Department of Water and Power (LADWP) | 40 |
| Oak View (unincorp.) | Ventura | Southern California Edison (SCE) | 34 |
| Hidden Hills | Los Angeles | Southern California Edison (SCE) | 21 |
| Valencia (Santa Clarita) | Los Angeles | Southern California Edison (SCE) | 15 |
| Somis (unincorp.) | Ventura | Southern California Edison (SCE) | 13 |
| Bell Canyon (unincorp.) | Ventura | Southern California Edison (SCE) | 13 |
| Oak Park (unincorp.) | Ventura | Southern California Edison (SCE) | 12 |
| Castaic (unincorp.) | Los Angeles | Southern California Edison (SCE) | 11 |
| Westlake Village | Los Angeles | Southern California Edison (SCE) | 6 |
| Piru (unincorp.) | Ventura | Southern California Edison (SCE) | 6 |
Sources
- 2025 Building Energy Efficiency Standards (Title 24, Part 6), Section 150.1(c) and Table 150.1-A
- 2025 Single-Family Residential Compliance Manual (CEC-400-2025-005)
Requirements shown are the 2025 prescriptive package (effective January 1, 2026) for newly constructed single-family buildings, which includes new detached ADUs. A performance (computer-modeled) approach can trade some items against others. Your Title 24 report confirms what applies to your project.
Need MEP plans and a Title 24 report in Climate Zone 9?
We prepare both from the same design, so the energy model and the equipment on the plans agree.
Start My Order