Window Climate Specs for Castro Valley, CA
ENERGY STAR groups Alameda County into its South-Central zone, which is the U-factor and SHGC target worth checking against any quote you get in Castro Valley. The longest-licensed window contractors based in Castro Valley are listed below the climate data.
Licenses checked · California Contractors State License Board
3CIECC climate zone · ENERGY STAR South-Central zone
Castro Valley's climate zone, in plain terms
Moisture and glass performance are handled by different parts of a window's spec sheet, and a Castro Valley buyer benefits from checking both instead of assuming one implies the other.
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 4.7 mi away.
What FEMA's risk data says about Castro Valley
FEMA scores Alameda County's winter-weather risk as Very Low and its flood risk as Very High.
Winter risk in Castro Valley 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 Castro Valley contractor, not one.
- Strong wind
- Very 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 Castro Valley 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.
Castro Valley's longest-licensed window installers
Oldest license first, newest last, pulled directly from the state's file. This list isn't for sale.
- Tanev Windows & DoorsVerify license
- Zeek's Discount Glass INCVerify license
- Mt Zion GlassVerify license
- Oscar's GlassVerify license