Title 24 in San Jose — Climate Zone 4
San Jose sits in California Title 24 Climate Zone 4, which sets the prescriptive baseline every San Jose residential project has to meet (or beat) under the energy code. The CEC assigns climate zones by ZIP code — every San Jose address resolves to CZ4 unless you're on an unusual edge ZIP (use the ZIP-code lookup tool to verify).
Prescriptive baseline for San Jose projects
These are the values your CF1R has to demonstrate compliance with. The prescriptive path matches them directly; the performance path can trade between them as long as the modeled energy use comes in at or under the reference design.
| Component | Value |
|---|---|
| Ceiling | R-38 (R-38 Ceiling Below Attic) |
| Walls | R-21+R5 CI, 2x6, Synthetic Stucco |
| Roof assembly | Asphalt Shingle, R-19 Below Deck, No RB |
| Radiant barrier | Not required |
| Window U-factor | U-0.27 |
| Window SHGC | 0.23 |
| Heating & cooling | Heat pump · HSPF2 9.0 / SEER2 17.0 / EER2 13.0 |
| Water heating | Heat-pump water heater (Tier 3 50-gallon HPWH) |
What this means for your San Jose design
In practice, walls go up at 2x6 with R-21 cavity insulation plus continuous-insulation sheathing on the outside, windows target SHGC 0.23, the heat pump needs HSPF2 9.0 / SEER2 17.0.
ADUs, additions, and alterations in San Jose
San Jose is one of California's most active markets for accessory dwelling units, additions, and addition-with-alteration projects. Each scope follows the same CZ4 prescriptive baseline shown above, with scope-specific adjustments built into the flow:
- Newly constructed ADUs (detached) get full PV sizing per the §150.1(c)14 prescriptive table.
- Attached ADUs and additions are treated as additions to the existing residence and skip PV sizing per §150.2(a).
- Alterations on a permitted residence run a focused alteration baseline; existing equipment (HVAC, water heater) is grandfathered unless you're replacing it.
Submitting your CF1R to City of San José Building Division
Your signed CF1R PDF gets submitted alongside your permit drawings to City of San José Building Division. The CF1R is registered with the CHEERS residential energy compliance registry — California's state-approved registry for residential CF1Rs. The registry assigns the certificate a unique ID that Santa Clara County plan-checkers verify when they review your submittal.
If City of San José Building Division returns a Title 24 correction on your plan-check letter, the plan-check response flow is built into the project dashboard — upload the correction letter and we'll analyze the cited items and route them to either a revised CF1R or a restart, depending on what changed.
Your three design options
San Jose projects choose between three pathways: Prescriptive (matches the CZ4 baseline above), 2x4 Performance (lighter framing, compensated by upgraded windows, roof, and equipment), and 2x6 Enhanced (heavier framing, easier equipment specs). Full breakdown on the Title 24 explained page.
Title 24 reports in other California cities
Los Angeles · San Diego · San Francisco · Sacramento · Long Beach · Oakland · Fresno · Bakersfield · Anaheim