Calculator Inputs
Enter building, climate, utility, envelope, lighting, ventilation, solar, and credit values. Results appear above this form after submission.
Formula used
Electric energy: kBtu = kWh × 3.412
Gas energy: kBtu = therms × 100
Lighting energy: kBtu = LPD × area × hours ÷ 1000 × 3.412
Fan energy: kBtu = fan W/cfm × cfm × hours ÷ 1000 × 3.412
Budget EUI: baseline EUI × climate factor × project factor × code cycle factor
Adjusted proposed EUI: ((site energy × envelope modifier × system modifier) − PV credit − battery credit − demand credit) ÷ floor area
Margin: budget EUI − adjusted proposed EUI
How to use this calculator
- Select the building type, project type, code cycle, and California climate zone.
- Enter conditioned floor area and the annual fuel values.
- Add lighting, fan, water heating, process, solar, battery, and demand response values.
- Enter envelope inputs, including window ratio, U-factor, SHGC, leakage, and insulation levels.
- Click calculate and review the result above the form.
- Download CSV or PDF results for early project notes.
Example data table
| Scenario | Area | Climate zone | Electricity | Gas | PV | Expected note |
|---|---|---|---|---|---|---|
| Efficient home | 2,500 ft² | 12 | 12,500 kWh | 240 therms | 6,500 kWh | Likely positive planning margin |
| High glass office | 18,000 ft² | 10 | 210,000 kWh | 4,200 therms | 25,000 kWh | Review glass and controls |
| Restaurant | 5,000 ft² | 15 | 190,000 kWh | 11,000 therms | 20,000 kWh | Process energy dominates |
Understanding California Energy Budgets
California Title 24 energy work compares a proposed building against a code budget. The official path uses approved modeling tools. This calculator gives a planning estimate. It helps teams check early design choices before formal documentation. The method starts with floor area. It then applies a baseline energy use intensity. Climate zone, project type, and code cycle change that budget. A hotter or colder zone usually needs more heating or cooling capacity. A new building also faces stronger expectations than a small alteration.
What the Estimate Includes
The calculator combines electricity, gas, water heating, process loads, lighting, fans, solar production, battery credit, and demand response credit. It also adjusts the result for envelope quality. Window area, glass values, leakage, roof insulation, and wall insulation affect the estimated load. Better insulation can reduce the adjusted energy use. Higher leakage can increase it. These inputs make the tool more useful than a simple energy conversion form.
Why Climate Zone Matters
California has many climate zones. Coastal areas, inland valleys, mountains, and deserts behave differently. Title 24 uses climate awareness because the same design does not perform equally everywhere. A window system may be acceptable near the coast yet weak in a hot inland zone. This calculator uses a simple multiplier for each zone. It is not a replacement for hourly modeling. It is a quick way to see direction and risk.
Reading the Result
The result shows estimated adjusted energy use intensity. It also shows the selected budget. A positive margin means the proposed estimate is below the planning budget. A negative margin means the design may need improvement. The percentage margin helps compare options. A small positive margin should still be reviewed carefully. Permit submittals need approved software and complete forms.
Useful Design Checks
Start with reasonable annual energy values. Add lighting and fan inputs only when those loads are not already included in the annual electricity number. Check solar credits after using expected production from a reliable design tool. Review envelope settings with plans, schedules, and specifications. Keep each revision documented. That makes later compliance modeling easier.
Best Use Cases
This tool works best during early design, cost review, or value engineering. It can compare window upgrades, insulation levels, lighting density, solar size, and equipment efficiency. It can also help owners understand why one design option has a better energy margin. Use it for planning conversations. Use certified Title 24 documentation for final permit approval.
Practical Limits
Energy codes contain detailed rules. They include mandatory measures, prescriptive paths, equipment requirements, controls, forms, and inspections. A calculator cannot judge every detail. It also cannot know every schedule, orientation, thermal bridge, or control sequence. Treat the output as a screening score. When the score looks weak, improve the design before spending time on final compliance work. Small early changes often protect budget, schedule, approval confidence, and review time.
FAQs
Is this a certified Title 24 compliance report?
No. It is a planning calculator. Use approved compliance software and required forms for permit submittals, plan checks, and official documentation.
What does the budget EUI mean?
Budget EUI is the simplified target energy intensity used by this tool. It changes with building type, project type, climate zone, and code cycle selection.
Why does climate zone change the result?
California climate zones have different heating, cooling, and solar exposure patterns. The calculator uses a planning multiplier to reflect that difference.
Should solar production be entered before or after losses?
Enter the expected annual AC production after typical system losses. The tool then applies a conservative planning credit to the entered value.
What if my electricity value already includes lighting?
Set lighting power density or lighting hours to zero. This avoids counting lighting energy twice in the proposed energy estimate.
Can I use this for residential projects?
Yes. Choose single family or multifamily. The output can support early decisions, but it does not replace residential compliance modeling.
Can I use this for nonresidential projects?
Yes. Choose office, retail, school, warehouse, restaurant, or healthcare. For final compliance, use approved nonresidential modeling and project forms.
What means a negative margin?
A negative margin means adjusted proposed EUI is above the selected planning budget. Review envelope, HVAC efficiency, lighting, controls, and solar options.
Why include battery and demand response credits?
They let teams compare grid supportive design ideas during early planning. Enter only credits supported by your project assumptions.
How should I choose the baseline override?
Use zero for the built in default. Enter a custom value only when an energy consultant provides a better planning baseline.
What should I do after getting a pass?
Keep refining inputs. Then run the project through approved software and prepare the required California energy compliance documentation.