CFA — Conditioned Floor Area
The heated/cooled square footage of the residence. Drives PV sizing and many Title 24 calculations.
CZ — Climate Zone
One of California's 16 climate zones, assigned by ZIP code. Sets the prescriptive baseline for insulation, windows, and HVAC. See the climate zones page.
CF1R — Certificate of Compliance, Residential
The design-stage Title 24 certificate, signed by the Responsible Person (your architect or licensed energy consultant) and submitted with your permit set.
CF2R — Certificate of Installation
Signed by the installing contractor once equipment (HVAC, water heating, etc.) is in.
CF3R — Certificate of Verification
Signed by an ECC Rater (formerly HERS Rater) after field verification of measures like duct leakage, refrigerant charge, and quality insulation installation.
ECC — Energy Code Compliance (formerly HERS)
The renamed third-party field-verification program (formerly the Home Energy Rating System) that confirms installed measures match the design. As of January 1, 2026, all HERS Providers and Raters are recognized as ECC-Providers and ECC-Raters.
CHEERS — California Home Energy Efficiency Rating Services
The sole CEC-approved ECC (formerly HERS) Provider in California. Registers Title 24 documentation and oversees the ECC-Raters who perform field verification. CF1Rs are filed here. See the CHEERS resources page.
ADU — Accessory Dwelling Unit
A secondary residence on the same lot as a primary home — e.g. a granny flat, garage conversion, or detached cottage. Treated as its own dwelling for PV sizing.
SHGC — Solar Heat Gain Coefficient
How much of the sun's heat a window lets through. Lower is better in cooling-dominated climates; the prescriptive Title 24 number ranges from 0.18 to 0.25 depending on climate zone.
U-factor
How fast heat flows through a window assembly. Lower is better. The prescriptive number for Title 24 windows is typically 0.30 in most California climate zones.
HSPF2 / SEER2 / EER2
Heating and cooling efficiency ratings for heat pumps and air conditioners. Higher is better. The "2" versions are the current (post-2023) test method; older HSPF / SEER / EER ratings without the "2" are now obsolete for code-compliance purposes.
UEF — Uniform Energy Factor
The current efficiency rating for water heaters. Higher is better. Heat-pump water heaters (HPWHs) typically rate UEF 3.0–4.0; gas storage tanks rate around 0.6–0.8.
HPWH — Heat-Pump Water Heater
A water heater that uses an air-source heat pump to extract heat from the surrounding air. Title 24 increasingly favors HPWHs over gas storage tanks for compliance.
RB — Radiant Barrier
A foil layer installed on the underside of the roof deck that reflects radiant heat back out before it reaches the attic insulation.
CI — Continuous Insulation
Rigid insulation board installed on the outside of the wall studs, on top of cavity insulation. Eliminates thermal bridging through the studs.
JA4 — Joint Appendix 4
The lookup tables of approved construction-assembly U-factors and R-values used in Title 24 compliance modeling. If a wall, roof, or floor assembly isn't in JA4, it has to be calculated separately.
RA3.5 — Reference Appendix 3.5
The ECC (formerly HERS) field-verification protocols for installed measures — quality insulation installation, duct testing, refrigerant charge measurement, and so on.
PV — Photovoltaic (solar)
The on-site solar electric system that Title 24 §150.1(c)14 requires on newly-constructed low-rise dwellings (including detached ADUs). Required system size in kW is calculated from conditioned floor area and dwelling-unit count using a prescriptive table; it appears on the CF1R. Additions, alterations, and attached ADUs are exempt under §150.2(a) and don't get a PV size on their CF1R.
AHJ — Authority Having Jurisdiction
The local building department or other reviewer that grants your construction permit. The AHJ is who actually accepts (or rejects) the CF1R you submit with your plans.
Now that you know the language, see your compliance options.
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