Window Climate Specs for Los Angeles, CA

Los Angeles sits in IECC climate zone 3B, which sets the energy-performance bar for any window installed here. Below that, a short list of Los Angeles's longest-licensed window contractors can turn a spec into an actual installed window.

Licenses checked September 30, 2026 · California Contractors State License Board

3BIECC climate zone · ENERGY STAR South-Central zone

Los Angeles's climate zone, in plain terms

Los Angeles falls in IECC climate zone 3B, and ENERGY STAR separately groups Los Angeles County into its South-Central zone for window certification.

Those two numbers, not the brand on the box, set the U-factor and SHGC worth checking on any quote you get in Los Angeles.

A Los Angeles-Long Beach-Anaheim, CA contractor who can't name either one on request is worth a second question before you sign.

Data: U.S. EPA / DOE, ENERGY STAR, ENERGY STAR Version 7.0 Climate Zones by County/ZIP (Windows, Doors, and Skylights) (V7.0); Pacific Northwest National Laboratory (DOE Building America), Guide to Determining Climate Zone by County: Building America and IECC 2021 Updates (PNNL-33270) (2021 IECC), from the nearest NOAA station 1 mi away.

What FEMA's risk data says about Los Angeles

FEMA scores Los Angeles County's winter-weather risk as Relatively Moderate and its flood risk as Very High.

Winter risk in Los Angeles weighs on U-factor and condensation resistance; flood risk weighs more on sill height and drainage detailing than on the glass package.

Treat these as two separate conversations with a Los Angeles contractor, not one.

Strong wind: Relatively Moderate
Winter weather: Relatively Moderate

Data: FEMA, National Risk Index for Natural Hazards - County-level table, v1.20 (v1.20, December 2025).

Guides to finish before Los Angeles window bids come in

How to Read an NFRC Window Label Four numbers on one sticker decide most of a window's real-world performance. Here's what each one means.
ENERGY STAR Window Criteria by Climate Zone ENERGY STAR splits the country into four zones, each with its own numbers. Here they are, and why the Northern zone works backward from the other three.
Impact Windows vs. Shutters in Florida's Hurricane Zones Florida gives homeowners two paths to a protected opening. Here's how each one is tested, and where the HVHZ raises the bar further.

Los Angeles's longest-licensed window installers

Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.

The Judson StudiosWindow and glass contractor · licensed 95 years · 90042Verify license
Conex Development Company INCWindow and glass contractor · licensed 42 years · 90041Verify license
Huntington Glazing INCWindow and glass contractor · licensed 40 years · 90032Verify license
A To Z Glass & Mirror INCWindow and glass contractor · licensed 38 years · 90022Verify license
Blue Moon Glass & Mirrors INCWindow and glass contractor · licensed 38 years · 90043Verify license
Atwater Screen And Glass ShopWindow and glass contractor · licensed 37 years · 90039Verify license
Ap Construction Glass & MirrorWindow and glass contractor · licensed 36 years · 90035Verify license
Giroux Glass INCWindow and glass contractor · licensed 34 years · 90015Verify license
Ruben's Glass Service INCWindow and glass contractor · licensed 34 years · 90066Verify license
Altered Glass INCWindow and glass contractor · licensed 34 years · 90023Verify license
Olympic Glass COWindow and glass contractor · licensed 33 years · 90011Verify license
Angels Glass & Mirror INCWindow and glass contractor · licensed 33 years · 90066Verify license

More California climate pages

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