Title 24 Reports in the Inland Empire

Riverside and San Bernardino counties are cooling-dominated, and the 2025 package shows it: fans, cool roofs, tight heat-gain limits and large solar arrays.

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Two counties, one region

The Bureau of Labor Statistics maps Riverside County and San Bernardino County, and only those two, to the Riverside-San Bernardino-Ontario metropolitan area, and this guide takes both. They are also in the Southern California Association of Governments' region, so the Southern California guide covers the coast and the basin. Pomona in Los Angeles County is zone 9, while Montclair next door is zone 10.

From valley to desert and mountain

The two counties hold 160 ZIP codes with a Census area: 80 in zone 10 (the valley), 30 in zone 14 (high desert), 28 in zone 15 (low desert) and 22 in zone 16 (mountains). A whole-house fan is required for a new house in zones 8 to 14, and steep roofing needs aged reflectance of 0.20 in zones 10 to 15. Zone 15 has no fan requirement, the tightest SHGC at 0.20 against 0.23, and a 0.63 reflectance on low-sloped roofs. Zone 14 uses U-0.27 windows where zones 10 and 15 use U-0.30. A 2,400 square foot house needs about 2.91 kWdc of PV in zone 10 and 5.21 in zone 15.

Who supplies the power

Edison is the main utility, but Corona says small areas are served by its own Department of Water and Power, and Rancho Cucamonga Municipal Utility serves over 3,900 metered customers and offers an incentive for new development that exceeds Title 24 by at least 15 percent. The Imperial Irrigation District reached the Coachella Valley in 1943 and serves over 150,000 customers in Imperial County and parts of Riverside and San Diego counties. The Energy Commission says adding PV for a detached ADU to an existing array depends on the load-serving entity allowing it.

Local rules and projects

Moreno Valley is the one Inland Empire city among the Energy Commission's ten approved ordinances for the 2025 code, setting a cooling requirement when an existing home's system is altered. Warehouses are a large part of the commercial work, and a low-sloped roof needs 0.63 aged reflectance in all sixteen zones, with a few exceptions: see warehouses and commercial solar and battery rules. Tract homes follow new-home compliance.

Every county, city and zone in the Inland Empire

Two counties and ten cities have their own pages, each noted with its zones.

See the locations page for other regions and the counties page for every county.

Order an Inland Empire report

Upload the plans and the address of the lot; the zone can differ across a county line. Start at $199 for an ADU, $245 for a home or $345 for multi-family. Unlimited revisions are included, and a 24-hour rush adds $95.

From $199 · ready in 2–3 days

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