How to read the results
The three sections — Heating, Cooling, and Water heating — show the prescriptive minimum that the 2025 Title 24 Energy Code (Table 150.1-A) expects for the chosen climate zone. Equipment that meets or exceeds these ratings can pass compliance on the prescriptive path without a performance trade-off calculation. The ratings shown are minimums: real equipment selection usually targets a margin above these values so a small spec change late in the project doesn’t blow compliance.
What the scope picker changes
Newly Constructed — full prescriptive baseline applies to every system. Heat pump for heating, high-SEER2 cooling, and a heat pump water heater (HPWH) are the default lineup.
Addition and/or Alteration — the existing equipment stays grandfathered unless you specifically replace it. Per the firm default for additions, a ductless mini-split is the typical new HVAC install when the addition has its own zone, and gas tankless is the typical water-heating spec when the existing fuel is gas. If the addition extends the existing ductwork, the existing equipment carries through unchanged. Replacement equipment must still meet the prescriptive minimums shown.
Alteration only — no new conditioned area added. Like Add+Alt, existing equipment is grandfathered; replacement equipment installed under this alteration must meet the same minimums.
For more depth
Browse all 16 zones
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