Title 24 Climate Zone 6: ADU Requirements

Where Climate Zone 6 is

Of the California places we cover, 46 are mostly in Climate Zone 6, across 4 counties: Los Angeles County, Orange County, Santa Barbara County, Ventura County. Together they issued 11,363 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 6, 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-30 ceiling; below roof deck: Not required
Attic, ducts-inside option	R-30 ceiling plus radiant barrier; ducts and air handler in conditioned space
Framed walls	Assembly U-factor 0.065 or lower
Cool roof	Not required
Whole-house fan	Not required
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 0.594) / 1000 + 1.23; none required under 1.8 kWdc (about 960 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 6

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 73°F in Avalon to 88°F in Fountain Valley, and the coldest winter design temperature is 29°F in Ventura. 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 6

Place	County	Electric utility	ADU permits 2021–25
Long Beach	Los Angeles	Southern California Edison (SCE)	3,015
Oxnard	Ventura	Southern California Edison (SCE)	1,265
Torrance	Los Angeles	Southern California Edison (SCE)	1,051
Westminster	Orange	Southern California Edison (SCE)	908
Santa Barbara	Santa Barbara	Southern California Edison (SCE)	683
Santa Monica	Los Angeles	Southern California Edison (SCE)	620
Venice (Los Angeles)	Los Angeles	Los Angeles Department of Water and Power (LADWP)	439
Huntington Beach	Orange	Southern California Edison (SCE)	437
Laguna Beach	Orange	Southern California Edison (SCE)	432
Wilmington (Los Angeles)	Los Angeles	Los Angeles Department of Water and Power (LADWP)	410
San Pedro (Los Angeles)	Los Angeles	Los Angeles Department of Water and Power (LADWP)	393
Costa Mesa	Orange	Southern California Edison (SCE)	391
Fountain Valley	Orange	Southern California Edison (SCE)	342
Ventura	Ventura	Southern California Edison (SCE)	249
Newport Beach	Orange	Southern California Edison (SCE)	234
Pacific Palisades (Los Angeles)	Los Angeles	Los Angeles Department of Water and Power (LADWP)	226
Redondo Beach	Los Angeles	Southern California Edison (SCE)	174
Carson	Los Angeles	Southern California Edison (SCE)	170
San Clemente	Orange	San Diego Gas & Electric (SDG&E)	143
Camarillo	Ventura	Southern California Edison (SCE)	134
Goleta	Santa Barbara	Southern California Edison (SCE)	134
Manhattan Beach	Los Angeles	Southern California Edison (SCE)	116
Harbor City (Los Angeles)	Los Angeles	Los Angeles Department of Water and Power (LADWP)	111
San Juan Capistrano	Orange	San Diego Gas & Electric (SDG&E)	109
El Segundo	Los Angeles	Southern California Edison (SCE)	105
Lomita	Los Angeles	Southern California Edison (SCE)	84
Port Hueneme	Ventura	Southern California Edison (SCE)	73
Rancho Palos Verdes	Los Angeles	Southern California Edison (SCE)	62
Hermosa Beach	Los Angeles	Southern California Edison (SCE)	52
Laguna Niguel	Orange	San Diego Gas & Electric (SDG&E)	50
Newbury Park (Thousand Oaks)	Ventura	Southern California Edison (SCE)	50
Signal Hill	Los Angeles	Southern California Edison (SCE)	43
Carpinteria	Santa Barbara	Southern California Edison (SCE)	43
Midway City (unincorp.)	Orange	Southern California Edison (SCE)	43
Dana Point	Orange	San Diego Gas & Electric (SDG&E)	42
Corona del Mar (Newport Beach)	Orange	Southern California Edison (SCE)	40
Rolling Hills Estates	Los Angeles	Southern California Edison (SCE)	38
Palos Verdes Estates	Los Angeles	Southern California Edison (SCE)	38
Playa del Rey (Los Angeles)	Los Angeles	Los Angeles Department of Water and Power (LADWP)	32
Malibu	Los Angeles	Southern California Edison (SCE)	29
Capistrano Beach (Dana Point)	Orange	San Diego Gas & Electric (SDG&E)	28
Laguna Hills	Orange	San Diego Gas & Electric (SDG&E)	22
Seal Beach	Orange	Southern California Edison (SCE)	13
Rolling Hills	Los Angeles	Southern California Edison (SCE)	8
Santa Rosa Valley (unincorp.)	Ventura	Southern California Edison (SCE)	6
Avalon	Los Angeles	Southern California Edison (Catalina Island isolated system)	5

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.