California's Energy Code splits the state into 16 building climate zones, and your zone sets several of the energy requirements in your Title 24 report. You can find your zone by address with the California Energy Commission's EZ Building Climate Zone Search Tool, or by ZIP code with the CEC's ZIP list.
What is a building climate zone?
A building climate zone is an area with similar weather for energy code purposes. The CEC says California has "a diversity of climates not seen in other states," so the Energy Code uses 16 zones instead of one statewide rule.
The zones are numbered 1 to 16. The CEC's compliance manual says every energy calculation must use the zone that applies to the building's physical location. The exact boundaries are defined in the CEC publication California Climate Zone Descriptions.
These are not USDA plant hardiness zones or the national IECC climate zones. Title 24 uses its own map.
How do I find my climate zone?
There are two CEC tools, both linked from the CEC's climate zone page:
- EZ Building Climate Zone Search Tool. Type in an address and the map shows the zone. This is the most precise option because it uses the actual zone boundaries.
- Climate Zone Assignments by ZIP Code. A downloadable spreadsheet with one zone per ZIP code.
What if my ZIP code crosses two zones?
Zone lines do not follow ZIP code lines. The CEC says: where a ZIP code contains more than one climate region, local jurisdictions may, at their discretion, pick one zone for the whole ZIP code. The ZIP list is provided "for the convenience of local jurisdictions electing to take this approach."
So:
- Look up your address in the EZ tool.
- Compare it with the ZIP list.
- If they differ, ask your building department which zone it uses for your ZIP code.
Some cities span more than one zone. In Los Angeles County, the CEC ZIP list puts Long Beach in zones 6 and 8, Torrance in zones 6 and 8, and the City of Los Angeles in zones 6, 8, 9 and 16.
Why does my climate zone change my Title 24 report?
The CEC says several standards, "such as those for envelope and fenestration (window and door) materials, depend on the specific climate zone." Examples from the 2025 CEC compliance materials:
| Requirement | Where it depends on zone |
|---|---|
| Cool roof for additions, steep-sloped roofs | Zones 10-15 |
| Cool roof for additions, low-sloped roofs | Zones 13 and 15 |
| Refrigerant charge testing, new air conditioners | Zones 2 and 8-15 |
| Refrigerant charge testing, new heat pumps | All 16 zones |
| West-facing glass limit for additions over 400 sq ft | Zones 2, 4 and 6-15 |
| Ceiling insulation for additions | R-38 in zones 1, 2, 4 and 8-16; R-30 in zones 3 and 5-7 |
| Radiant barrier for additions | Zones 2-15 |
| Max window U-factor, additions and alterations | 0.27 in zones 1-5, 11-14 and 16; 0.30 in zones 6-10 and 15 |
For performance reports, the compliance software uses weather data for your zone. Your design is compared against a standard design built for that same zone. The same house can pass in one zone and need upgrades in another.
Which climate zones are in Los Angeles County?
From the CEC ZIP list, for the cities we cover:
| City | Climate zone(s) by CEC ZIP list |
|---|---|
| El Monte | 9 |
| Pasadena | 9 |
| Alhambra | 9 |
| West Covina | 9 |
| Long Beach | 6 (most of the city) and 8 (north Long Beach) |
| Torrance | 6 (most ZIPs) and 8 (ZIPs 90504 and 90506) |
| Los Angeles | 9 (most of the city), 8, 6 and 16 |
Always confirm a specific address with the EZ tool.
What do I need to tell my energy consultant?
Just your project address. Your consultant looks up the zone and puts it on the CF1R. If the address sits near a zone line, they should check the EZ tool and your building department's rule.
Need a report for your zone? See our flat prices.
Frequently asked questions
How many climate zones does California have for Title 24?
Sixteen. The California Energy Commission divides the state into 16 building climate zones, and several Energy Code requirements depend on which zone a building is in.
How do I find my climate zone?
Use the CEC's EZ Building Climate Zone Search Tool, which looks up an address. The CEC also publishes a list of climate zones by ZIP code.
What if my ZIP code is in two climate zones?
The CEC says that where a ZIP code contains more than one climate region, the local building department may choose one zone for the whole ZIP code. The CEC's ZIP list exists for departments that take that approach. Check the address with the CEC tool and ask your building department which one it uses.
Are these the same as USDA or IECC climate zones?
No. Title 24 uses California's own 16 building climate zones, set by the California Energy Commission.
What changes with climate zone?
Envelope and window requirements, cool roof rules, which air conditioners need refrigerant charge testing, west-facing glass limits, and the energy budget your design is compared against.
Related
Sources
- energy.ca.gov/programs-and-topics/programs/building-energy-efficiency-standards/climate-zone-tool-maps-and
- energy.ca.gov/media/3560
- energy.ca.gov/sites/default/files/2020-04/BuildingClimateZonesByZIPCode_ada.xlsx
- energy.ca.gov/filebrowser/download/8625?fid=8625
- energy.ca.gov/filebrowser/download/8641?fid=8641
- energy.ca.gov/programs-and-topics/programs/building-energy-efficiency-standards/energy-code-support-center-6/2025