Title 24 Reports in San Luis Obispo County

Coast and North County

Zone 5 is the larger share — 17 of the 23 ZIP codes we derive for the county — and covers San Luis Obispo itself, Morro Bay, Los Osos, Pismo Beach, Arroyo Grande and the coastal strip. Zone 4 covers the inland North County: Paso Robles, Atascadero, Templeton, Santa Margarita and the country east of them.

The division tracks the coastal range. West of it the ocean moderates temperatures year-round; east of it, summer afternoons are markedly hotter and winter nights colder.

The same distinction the wine industry draws

Anyone who knows the county's viticulture already knows this boundary — it is the reason the coastal and inland growing areas behave so differently. The Energy Code is drawing the same line for the same reason, which makes the zone split easier to reason about here than in a county whose geography is less legible.

Why it changes a report

Zone 5 has modest cooling loads and a mild winter, so a compliant design can be relatively straightforward. Zone 4 has real summer cooling demand, so glazing on west and south elevations, shading and equipment efficiency carry more weight. A specification developed for a coastal project does not simply transfer inland.

Example ZIP codes and their zones

Derived from the Energy Commission's ZIP-to-climate-zone table, with county membership taken from the U.S. Census Bureau's 2020 ZCTA-to-county relationship file:

• Climate zone 4 — 93422, 93432, 93446, 93453, 93465 and 1 more
• Climate zone 5 — 93401, 93402, 93420, 93442, 93449 and 12 more

Every ZIP code here sits inside the county

Unusually, none of the ZIP codes we derive for San Luis Obispo County is materially shared with a neighbouring county. In most of California a county's ZIP codes straddle its boundaries, which is one reason a ZIP code is a better guide to requirements than a county name.

Finding the zone for your own project

The zone is set by the project's location and confirmed from the ZIP code against the Energy Commission's published table — not from the county name and not from the nearest large town. Because San Luis Obispo County contains more than one zone, that check decides which set of numbers a report is written against.

Give us the project address and we determine the zone as part of preparing the report. It is the first thing established, because every insulation, glazing and equipment figure downstream depends on it.

City and unincorporated permitting

A project inside a city's limits is permitted by that city. A project on unincorporated land is permitted by the county instead, and the two can run different submittal processes even where the energy requirements are identical. The California Energy Code is statewide — what changes locally is the climate zone the site falls in and how the jurisdiction wants the compliance documents presented.

Climate zones in San Luis Obispo County

San Luis Obispo County contains California climate zones 4 and 5. The zone drives the insulation, glazing and equipment performance a report has to demonstrate, and it is confirmed from the project ZIP code against the Energy Commission's published table.