Window Climate Specs for Brentwood, CA
Brentwood sits in IECC climate zone 3B, which sets the energy-performance bar for any window installed here. Below that, a short list of Brentwood's longest-licensed window contractors can turn a spec into an actual installed window.
Licenses checked · California Contractors State License Board
3BIECC climate zone · ENERGY STAR South-Central zone
Brentwood's climate zone, in plain terms
San Francisco-Oakland-Fremont, CA runs a January average near 48°F and climbs to about 76°F by July, a swing that adds up to roughly 2,230 heating degree days most winters, with 1,345 on the summer cooling side of the ledger.
That load is the actual argument for paying up for a better U-factor in Brentwood, separate from anything a brochure claims.
Zone 3B's requirement is the floor; Brentwood's specific load is what tells you whether beating that floor is worth the extra cost.
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 3.8 mi away.
What FEMA's risk data says about Brentwood
Contra Costa County's hail risk sits at Very Low and its wildfire risk at Relatively Moderate, according to FEMA's National Risk Index.
Hail risk matters for glass and screen durability in Brentwood; wildfire risk matters more for the frame material and nearby vegetation than for the glass itself.
Either way, it's a reasonable question to bring to a Brentwood installer before you settle on a product line.
- Strong wind
- Relatively Low
- Winter weather
- Very Low
Data: FEMA, National Risk Index for Natural Hazards - County-level table, v1.20 (v1.20, December 2025).
Guides to finish before Brentwood 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.
Brentwood's longest-licensed window installers
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- All - Pro Glass INCVerify license
- Saboo INCVerify license
- Delta WindowsVerify license
- Faction Glass Solutions INCVerify license
- JPRL GlassVerify license
- Goat GlassVerify license
- Barnett Glass Company LLCVerify license