What Danville Homes Need From a Replacement Window
ENERGY STAR groups Contra Costa County into its South-Central zone, which is the U-factor and SHGC target worth checking against any quote you get in Danville. The longest-licensed window contractors based in Danville are listed below the climate data.
Licenses checked · California Contractors State License Board
3BIECC climate zone · ENERGY STAR South-Central zone
What zone 3B means for a Danville window
Danville falls in IECC climate zone 3B, and ENERGY STAR separately groups Contra Costa 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 Danville.
A San Francisco-Oakland-Fremont, 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 5.1 mi away.
Storm and weather risk around Danville
Neither rating changes a window's energy label, but both are exactly what impact-resistance and design-pressure ratings are built to answer for a Danville home.
Ask specifically about design pressure and impact rating for Danville, not just energy performance, if either risk rating comes back on the high side.
- 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 Danville 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.
Window installers with the longest license records in Danville
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- L & L Window Products CorporationVerify license
- Fenton ConstructionVerify license
- All American Glass & Shower INCVerify license
- G Forster Construction INCVerify license