Reference
NFRC CPD codes: the key to a window label
A certified performance figure is a claim about one tested configuration. The CPD entry behind it is written in a code system that says exactly what that configuration was — which opening, which frame, which break, which gas, which spacer. These are the eight lookup tables those codes come from. They are reproduced here so a specifier reading a third-party label, or comparing two entries, can decode it without a phone call.
What a CPD entry carries
The codes below feed the columns of an NFRC ratings table. Knowing which column each code lands in is what turns a wall of letters into a specification.
CPD #
the certification entry this configuration is listed under
Glazing type
the pane build, read through the tint and gap-fill codes
Glass thickness
each pane, in the order the light passes through
Gap width
the cavity between panes
Gap fill
air, argon, krypton — the gap-fill codes
U-value
whole-unit heat loss, per ANSI/NFRC 100
CR
condensation resistance, per ANSI/NFRC 500
ER rating no
the energy rating entry, where the market uses one
SDL
simulated divided lite, split by width because the grid changes the value
Coating
the low-e surface, by number — #2, #3, #4, #5
Species
timber species, where the frame is not aluminium
The eight code tables
195 codes, transcribed from the NFRC lookup tables. Nothing here is a house interpretation — a code decoded wrongly is more dangerous than no table at all.
Source: the NFRC code lookup tables as published in the industry code keys. The code system is North American; EN 12208 and EN 12210 class the same physical decisions differently, and AS 2047 runs its own test set.
Product type codes45 codes
The opening itself. Rows marked "project-out" describe a configuration the CPD entry covers for a specific project rather than as a standing catalogue listing — they still appear on real labels.
Frame and sash codes44 codes
What the frame and sash are made of, and whether a thermal break is present. AL / AP / AT is the aluminium ladder a European reader will map onto "non-broken / partially broken / broken".
Thermal break material codes11 codes
The material in the break. PA66 GF25 polyamide is the structural choice; PVC and poured polyurethane appear on cheaper builds and age differently.
Gap fill codes12 codes
What fills the cavity between the panes. Argon is the working default; krypton buys a narrower gap, xenon and SF6 are legacy.
Tint codes17 codes
Body tint and interlayer type. This is where laminated and acoustic builds separate from plain float.
Spacer codes59 codes
The edge seal construction, and the single largest driver of the difference between a warm-edge and a cold-edge unit. The suffix carries the seal: -D dual sealed, -S single sealed, -N wood (no seal designation). Aluminium codes sit at A1-A9, stainless at S2-S6 and SS/SU, thermoplastic at TP and TS, silicone foam at ZE and ZF.
Grid codes4 codes
Divided-lite construction, and whether the grid sits between the panes or on the outside faces.
Grid size codes3 codes
The simulated divided-lite width, in inches.
Reading a label without guessing
What is a CPD number?
A CPD number is an entry in the NFRC Certification Products Directory. It identifies one tested configuration — a frame, an operation, a glazing build — with the measured values attached. Two products with different CPD numbers were tested as different things, even where the marketing looks the same.
Where do these codes actually appear?
On the NFRC label that ships with a certified unit, and in the ratings tables a manufacturer publishes. The product type, frame, break, fill, tint and spacer codes compose the CPD entry; the U-value, SHGC, VT and CR figures are what the entry certifies.
Do these codes apply outside North America?
The code system is North American. EN 12208 and EN 12210 class air, water and wind differently, and AS 2047 runs its own test set — but the fields the codes describe — glazing build, gas fill, spacer, frame material — are the same physical decisions everywhere. Reading the code tells you what was actually built.
How do I check a CPD entry?
Take the CPD number and the manufacturer name and look the entry up in the NFRC directory. Check that the tested size covers your largest opening, that the glass build matches what you are specifying, and that the report date is current for the profile being produced. A certificate that names a different configuration does not certify yours.
The same discipline runs through our own documentation. A report names the laboratory, the series tested and the values measured — see certifications and test standards. Where a figure on this site is quoted, it belongs to a named configuration, not to a product family in general.