JA5 OCST Savings Calculator
Estimate avoided solar PV, battery storage, and HVAC interface CAPEX enabled by a JA5 OCST under Title 24 performance modeling.
Replace with CBECC-Res & CF1R values before quoting.
Enter ductless model ratings to calculate additional PV & battery savings from equipment efficiency gains beyond the JA5 OCST credit. Leave blank to use the flat 20% inverter efficiency assumption.
| Scenario | PV Red | Batt Red | Total Savings |
|---|---|---|---|
| Low | — | — | — |
| Base ● | — | — | — |
| High | — | — | — |
Appendix & Reference
California Energy Commission (CEC) 2025 Building Energy Efficiency Standards for Residential and Nonresidential Buildings.
→ 2025 Building Energy Efficiency Standards (CEC)JA5 defines the qualifying criteria for OCST devices under Title 24. A thermostat must appear in the CEC JA5 approved device list to qualify for the demand-flexibility credit in CBECC-Res performance modeling.
→ CEC JA5 Approved Device DatabaseThe Title 24 performance path requires hourly energy simulation using CEC-approved software. CBECC-Res is the reference tool; EnergyPro is the primary third-party tool used by California consultants.
→ CBECC-Res (CEC)→ EnergyPro (EnergySoft)
California is divided into 16 Building Climate Zones based on weather data. The CZ determines mandatory system sizing, compliance targets, and the energy credit value of OCST demand flexibility.
→ CEC Interactive Climate Zone MapSEER2 and HSPF2 are the 2023 DOE test procedure ratings (effective Jan 1 2023, replacing legacy SEER/HSPF under the M1 test method). The calculator includes 10 Flair-compatible ductless model presets sourced from AHRI certified product data. Verify against current AHRI listings before use in formal analysis.
→ AHRI Certified Products DirectoryThe $0.25/kWh default CA residential rate is based on CPUC and CEC reported averages for California investor-owned utility service territories (2024–2025).
→ CPUC Electric RatesThe mandatory minimum system sizes are auto-calculated from unit count and conditioned floor area (CFA) per Title 24 §150.1(c)14:
When ductless SEER2 and HSPF2 ratings are entered, the calculator derives an additional PV and battery reduction from the efficiency delta between the specified ductless model and the code-minimum ducted baseline.
| CZ | Cooling | Heating | Character |
|---|---|---|---|
| 1 | 35% | 65% | Humid coast / heating dominated |
| 2 | 40% | 60% | North Coast |
| 3 | 30% | 70% | Central Coast |
| 4 | 45% | 55% | N. Bay inland |
| 5 | 25% | 75% | South Coast marine |
| 6 | 55% | 45% | South Coast |
| 7 | 65% | 35% | San Diego coastal |
| 8 | 70% | 30% | LA basin |
| 9 | 75% | 25% | LA inland valley |
| 10 | 80% | 20% | Inland empire / cooling dominated |
| 11 | 70% | 30% | Sacramento valley |
| 12 | 65% | 35% | Sacramento / mixed |
| 13 | 80% | 20% | San Joaquin valley |
| 14 | 65% | 35% | High desert |
| 15 | 90% | 10% | Imperial valley |
| 16 | 35% | 65% | Mountain |
| Parameter | Default | Source |
|---|---|---|
| PV sizing | 1.5 W/sf × CFA | T24 §150.1(c)14A |
| Battery sizing | 7.5 kWh/unit | T24 §150.1(c)14B |
| Baseline SEER2 | 14.3 | 2023 federal minimum (ducted) |
| Baseline HSPF2 | 7.5 | 2023 federal minimum (ducted) |
| Parameter | Default | CA Market |
|---|---|---|
| PV installed | $3,000/kW | $2,000–$3,500/kW |
| Battery installed | $800/kWh | $650–$1,000/kWh |
| HVAC controls | $250/dev | $150–$400/dev |
| Flair Puck | $124/dev | List price |
| CA electricity | $0.25/kWh | $0.22–$0.32/kWh |
| CZ Group | PV Low | PV Base | PV High | Batt Low | Batt Base | Batt High |
|---|---|---|---|---|---|---|
| CZ 1–4 | 3% | 5% | 7% | 6% | 10% | 12% |
| CZ 5–8 | 4% | 6% | 8% | 8% | 12% | 15% |
| CZ 9–16 | 5% | 7% | 9% | 10% | 14% | 18% |
| Term | Definition |
|---|---|
| Title 24 Part 6 | California's Building Energy Efficiency Standards, updated every 3 years by the CEC. |
| JA5 / OCST | Joint Appendix 5. Defines an Occupant-Controlled Smart Thermostat — a device that enables demand-flexibility and qualifies for compliance credits in the performance path. |
| Performance Path | A compliance method where a building's proposed energy use is modeled hourly against a code-standard design. |
| TDV Energy | Time-Dependent Valuation — a weighting factor that values energy by the time of day and season it is consumed or generated. |
| CF1R | Certificate of Compliance for Residential Buildings — the compliance document generated by CBECC-Res or EnergyPro. |
| CFA | Conditioned Floor Area — the total floor area of spaces that are heated or cooled. |
| §150.1(c)14 | The section of Title 24 Part 6 that mandates minimum solar PV and battery storage for new residential construction. |
| Term | Definition |
|---|---|
| SEER2 | Seasonal Energy Efficiency Ratio 2. Measures cooling efficiency under the DOE M1 test procedure (effective Jan 2023). Convert legacy SEER × 0.95 ≈ SEER2. |
| HSPF2 | Heating Seasonal Performance Factor 2. Measures heating efficiency under the M1 test procedure. Convert legacy HSPF × 0.85 ≈ HSPF2. |
| Ductless mini-split | A heat pump system without ductwork. Wall-mounted indoor unit connects directly to outdoor compressor. Eliminates duct losses. |
| Inverter-driven | A compressor that varies speed continuously to match load. Significantly more efficient at part-load conditions. |
| BESS | Battery Energy Storage System — a grid-connected battery that stores solar generation. |
| PV | Photovoltaic — solar panels that convert sunlight to electricity. |