Manual J calculator · CA
Manual J load calculation for California.
Run an ACCA Manual J 8th Edition residential load calculation with climate context pre-loaded for California — ASHRAE design temperatures for 5 top metros, California Title 24 Part 6 (2022 cycle, effective 2023-01-01), and CSLB licensing context already accounted for in the assumption defaults.
Pre-loaded scenario
Los Angeles, CA (Los Angeles County) · ASHRAE zone 3B · winter 99% DB 43°F · summer 0.4% DB 89°F · MCWB 69°F.
ASHRAE 169-2021 · ACCA MJ8 §6
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01 · ASHRAE design conditions
Top 5 metros in California — design temperatures used in Manual J.
These are the ASHRAE 99% heating and 0.4% cooling design temperatures — the values Manual J uses for the design day, not the absolute extremes. Equipment sized to these conditions undersizes for ~35 hours per year in summer (acceptable per ACCA convention) and ~22 hours per year in winter.
| Metro | County | Zone | Winter 99% DB | Summer 0.4% DB | MCWB |
|---|---|---|---|---|---|
| Los Angeles | Los Angeles County | 3B | 43°F | 89°F | 69°F |
| San Francisco Bay Area | San Francisco / Alameda County | 3C | 39°F | 84°F | 64°F |
| San Diego | San Diego County | 3C | 44°F | 83°F | 69°F |
| Sacramento | Sacramento County | 3B | 33°F | 100°F | 70°F |
| Riverside–San Bernardino | Riverside / San Bernardino County | 3B | 35°F | 102°F | 70°F |
Source: ASHRAE 169-2021 (republished in EERE Building America Guide 7.3, public domain). DB = dry-bulb. MCWB = mean coincident wet-bulb at the 0.4% cooling design hour.
02 · Energy code
California energy code: California Title 24 Part 6 (2022 cycle, effective 2023-01-01)
Adopted 2023. Manual J load-calc documentation requirements flow from the state energy code; verify your specific AHJ’s submittal rules before relying on the baseline.
- California does not adopt the IECC directly — Title 24 Part 6 is the state-specific energy code, set on a 3-year cycle by the California Energy Commission.
- The 2022 code adds heat-pump baseline requirements for new construction in most CEC climate zones, raising the effective cost-of-compliance for gas-furnace replacements.
Source: California Energy Commission — Building Energy Efficiency Standards (Title 24, Part 6) · verified 2024-09-15
03 · California HVAC labor data
BLS wages and employment for HVAC mechanics in California.
These are state-level wages for occupation code 49-9021 — Heating, Air Conditioning, and Refrigeration Mechanics and Installers — from the most recent BLS Occupational Employment and Wage Statistics release.
- Median hourly wage
- $30.86
- Mean annual wage
- $67,220
- Employment estimate
- 30,960
Source: BLS OEWS May 2023, SOC 49-9021 (state-level) · released 2024-04-03. Loaded labor rates billed to customers typically run 2.5–3.5× the technician wage after overhead.
04 · License & permit
HVAC licensing in California: CSLB.
State-level HVAC contractor licensing is administered by the California Contractors State License Board. Licenses renew every 2 years.
License types
- C-20 Warm-Air Heating, Ventilating and Air-Conditioning Contractor
- C-38 Refrigeration Contractor
- B-General Building Contractor (allows HVAC scope on most residential projects)
Permits
California Title 24 Part 6 § requires HERS-verified airflow and refrigerant charge for most residential HVAC change-outs in addition to the standard mechanical permit. Local AHJs may require energy compliance forms (CF-1R, CF-2R, CF-3R) at submittal.
Replacement permit: typically required.
California's HERS verification adds an inspection step beyond the standard permit — budget for the registered HERS rater on every change-out, not just new construction.
05 · FAQ
Common Manual J questions for California contractors.
+Does California's Title 24 require ACCA Manual J?
Title 24 Part 6 §150.1(c) requires HVAC equipment to be sized according to ACCA Manual J for new residential construction. For change-outs, the standard is more flexible — many AHJs accept a documented load calculation that's consistent with Manual J methods, which BuildSolver provides with its audit trail.
+Why is the SF Bay Area in zone 3C?
Zone 3C is the marine-influenced 'warm marine' zone. Coastal California from San Francisco south to San Diego sits in 3C — mild summers (84°F design DB), mild winters (39–44°F design DB), and very low diurnal range. Manual J wall U-factors here drive less load than radiative gain through unshaded glass.
+What's a C-20 vs C-38 license?
C-20 is the warm-air heating + ventilating + AC license — the broadest HVAC scope. C-38 is the refrigeration-only license, used by commercial refrigeration and cold-storage contractors. Most residential HVAC contractors hold C-20.
+How does Sacramento's design temp differ from coastal California?
Sacramento is inland zone 3B — 100°F summer design DB, 33°F winter — about 16°F hotter in summer than coastal 3C zones. Manual J output for a 2,000 sqft house in Sacramento can be 30–40% higher than the same house in San Francisco, primarily on sensible cooling.
+Is BuildSolver compatible with California's HERS verification process?
BuildSolver provides the Manual J load calculation that feeds into the equipment sizing decision. The HERS rater independently verifies airflow and refrigerant charge at install — that's a separate measurement done by a registered third party. BuildSolver doesn't replace the HERS rater; it documents the design-side sizing rationale.
+Why is the California HVAC wage so much higher than the national median?
BLS OEWS May 2023 reports $30.86/hr median in California vs $25.74 nationally — about 20% above national. Cost-of-living, prevailing wage on public-works projects, and unionization (especially in Bay Area and Sacramento) all contribute.
Try a California load calculation now.
The chat will ask follow-up questions like an experienced engineer — square footage, construction type, window count, insulation level — and run the Manual J on your inputs with California’s ASHRAE design temperatures applied automatically. About 90 seconds end to end.
Start California calculationRelated · same climate zone
Other states with similar ASHRAE climate zones.
Manual J assumptions for infiltration, latent share, and design temperatures behave similarly across states that share an ASHRAE zone. The pages below carry the same procedural defaults with their own local design temps and licensing context.
Data last reviewed 2026-05-19 · underlying sources as of 2024-04-03