Title 24 Reports in Imperial County

Fourteen of fifteen ZIP codes are zone 15

Zone 15 is the low-desert assignment, and in Imperial County it covers almost everything. All seven incorporated cities on the Department of Finance's 2026 estimates are in it — El Centro, Calexico on the border, Brawley, Imperial, Holtville, Calipatria and Westmorland. So are Heber just south of El Centro and Ocotillo in the west. Toward the Salton Sea, Niland and Bombay Beach are zone 15; across the river from Yuma, so is Winterhaven.

Within those seven cities' limits the city permits the work; outside them, the county does, and that includes Palo Verde, which is unincorporated.

This is the most cooling-dominated zone in California. Solar gain through glazing, cooling equipment efficiency, duct tightness: these decide a zone 15 report, while heating is a minor line in it.

Palo Verde, between two zone 15 towns

Zone 14 is the high-desert classification of the Antelope Valley and the Mojave. In Imperial County it appears on exactly one ZIP code, 92266, which serves Palo Verde at the county's north-eastern edge and takes in a large, thinly settled stretch of desert around it.

The neighbours make it worth a second look. Blythe, a short way up the Colorado in Riverside County, is zone 15. So is Winterhaven, at the southern end of Imperial's river frontage. Palo Verde sits between them in the other zone.

Same desert, different weighting

Zone 14 targets weigh winter heating alongside summer cooling, because the high desert has both. Zone 15 targets are written almost entirely around the summer. A design proven for El Centro is not automatically proven for Palo Verde, even though the two share a county and a desert.

Every ZIP code by zone

Zones per the Energy Commission; county membership and community names per the 2020 Census.

• Climate zone 14 — 92266 (Palo Verde)
• Climate zone 15 — 92222; 92227 (Brawley); 92231 (Calexico); 92233 (Calipatria); 92243 (El Centro, Seeley); 92249 (Heber); 92250 (Holtville); 92251 (Imperial); 92257 (Niland, Bombay Beach); 92259 (Ocotillo); 92273 (Seeley); 92275 (Salton City); 92281 (Westmorland); 92283 (Winterhaven)

No ZIP code here is split

Each lies wholly inside Imperial County by Census land area — including 92266, which is why that single ZIP is enough to establish zone 14 here.

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 Imperial 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.

Climate zones in Imperial County

Imperial County contains California climate zones 14 and 15. 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.