Windows are one of the easiest places to fail a Washington energy inspection, and one of the easiest to get right if you know what the inspector is checking. This guide covers the essentials for residential new construction.
Codes are updated regularly and local jurisdictions can add their own rules, so always confirm the current requirements for your project with your plans examiner.
The number that matters most: U-factor 0.30
The Washington State Energy Code sets a maximum U-factor of 0.30 for windows on new homes under the standard (prescriptive) path. U-factor measures heat loss through the whole window, so a lower number is better. A window rated 0.31 does not pass; a window rated 0.30 or lower does.
Two details trip builders up:
- The rating must be for the whole unit. Center-of-glass figures do not count. The code uses the NFRC certified rating for the complete window, frame and glass together.
- The rating depends on the glass package. The same frame can rate differently with different glass. Make sure the package on your order is the one that was certified at 0.30 or lower.
NFRC labels: leave them on
Inspectors match each installed window to the plans and the energy compliance paperwork using the NFRC label on the glass. If the labels are gone, the inspector may not be able to verify the windows, which can mean a delay or a re-inspection.
Make it a rule on site: labels stay on until the energy inspection is signed off.
Other things to check
Safety glazing
Separate from the energy code, the building code requires tempered (safety) glass in hazardous locations, for example near doors, in or beside tubs and showers, and in large, low panes. Check your plans against these locations before ordering, because changing glass after delivery is slow and expensive.
Egress
Bedroom windows have to meet emergency escape size and sill height rules. Casements and single hungs handle this differently, so confirm the clear opening for each bedroom window size, not just the rough opening.
Glazing area and the performance path
If a design uses a large amount of glass, the standard path may not be the easiest route. Some projects use a performance or trade-off approach where better windows offset other parts of the design. Your energy consultant or plans examiner can tell you which path fits the house.
How PuroCima lines up
Every PuroCima window is NFRC certified, and for each order we spec a glass package that meets the Washington requirement of a 0.30 U-factor or lower. Certified ratings across the range run from 0.27 to 0.30:
- Single hung: U-0.30, SHGC 0.24, VT 0.42
- Horizontal slider: U-0.27, SHGC 0.23, VT 0.49
- Casement: U-0.29, SHGC 0.25, VT 0.46
- Picture window: U-0.28, SHGC 0.23, VT 0.45
- Sliding patio door: U-0.27, SHGC 0.45, VT 0.61
A simple pre-order checklist
- Confirm every window on the schedule is U-0.30 or lower as a whole unit.
- Mark the safety glazing locations and specify tempered glass there.
- Check egress sizes for every bedroom.
- Ask your supplier for the NFRC listings for your exact products.
- Brief the crew: labels stay on until inspection.
Want a second set of eyes on your schedule? Send it over for a quote and we will spec each opening against the code before anything is ordered.