Questions covered in this guide
Keep the labels with the quote
Ask for the NFRC ratings for the window configuration in your proposal. Record the product, operating style, glass option and the quoted rating values together. A rating for another configuration is not an answer about the window you are considering.
Read the two measures separately
NFRC describes a lower U-factor as better resistance to heat escaping. Solar heat gain coefficient, or SHGC, describes solar heat gain through the product. The climate and the objective matter when interpreting that value. Ask the installer to explain the proposed specification for each exposure rather than assuming one attractive number settles the selection.
Check the paperwork before ordering
The NFRC Certified Products Directory provides a way to check rating data from a label. Ask for enough product identification to perform that check. If the order changes, update the record before comparing the new option with the old quote. This is especially helpful when a price reduction comes from a different glass package rather than a lower price for the same product.
Keep installation in the conversation
Product ratings describe the product, not a guarantee of the completed installation. Request the installation scope separately, including how the existing opening and finishing work will be handled. Build an opening list for our window planning tool and retain the proposed specifications alongside it. A lower energy rating number does not translate directly into a promised reduction in your whole-house utility bill, and this guide does not determine local code compliance.
Putting it into practice
Compare a labeled configuration rather than a brand name. Keeping the order specification and rating values together makes a changed glass package visible when a bidder revises the price.
Sources and supported claims
NFRC explains U-factor and solar heat gain coefficient as distinct window performance measures.
Source ↗ · national · Checked 2026-10-12
The NFRC Certified Products Directory supports checking rating data shown on a product label.
Source ↗ · national · Checked 2026-10-12
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