Aluminum Sliding Windows from China: Test Standards, Energy Ratings and US Duty Scope
What the ASTM window test methods, ENERGY STAR/NFRC rules, China's GB/T 8478-2020 standard and the US duty scope say for buyers of aluminum sliding windows from China, with a link to each source.
How to read this guide
Not legal or engineering advice. This guide lists the public test methods, energy-rating rules, Chinese national standard and US duty scope that come up when importing aluminum sliding windows from China. Each statement links to the page it comes from. Confirm the exact requirements for your project with your specifier, code official or customs broker.
It does not name or rank manufacturers and does not quote prices, minimum orders or lead times; ask each supplier for those in writing.
Test methods buyers see in window specifications
ASTM E283/E283M is a laboratory procedure for determining the air leakage rates of exterior windows, skylights, curtain walls and doors under specified differential pressure conditions across the specimen. Source: ASTM E283/E283M-19, Scope and Significance and Use.
ASTM E283 measures only leakage associated with the assembly, not the installation; field tests on installed units are covered by ASTM E783. Source: ASTM E283/E283M-19, Scope and Significance and Use.
ASTM notes that air leakage rates may not be valid for comparison unless the components tested are of essentially the same size, configuration and design. Source: ASTM E283/E283M-19, Scope and Significance and Use.
ASTM E331 determines the resistance of exterior windows, curtain walls, skylights and doors to water penetration when water is applied to the outdoor face and exposed edges together with a uniform static air pressure at the outdoor face higher than at the indoor face. Source: ASTM E331-00(2023), Scope and Significance and Use.
ASTM E330/E330M determines the structural performance of exterior windows, doors, skylights and curtain walls under uniform static air pressure differences, using a test chamber, and typically represents the effects of a wind load. Source: ASTM E330/E330M-14(2021), Scope and Significance and Use.
ASTM E330 states that U.S. practice for wind load testing has generally required a minimum test period of 10 s for test loads equal to the design wind load and for proof loads equal to 1.5 times the design wind load. Source: ASTM E330/E330M-14(2021), Scope and Significance and Use.
ASTM E330 is not intended to account for windborne debris or cyclic loads; those are addressed by ASTM E1233/E1233M, E1886 and E1996. Source: ASTM E330/E330M-14(2021), Scope and Significance and Use.
Because each test result belongs to the specimen that was tested, ask for the report that matches the exact profile series, size and glazing you are ordering.
Energy ratings: ENERGY STAR and NFRC
ENERGY STAR certified windows are made by an ENERGY STAR partner, have their energy performance independently tested and certified through the National Fenestration Rating Council (NFRC), and have NFRC ratings that meet guidelines set by the US Environmental Protection Agency. Source: ENERGY STAR, "What makes it ENERGY STAR?" (US EPA).
ENERGY STAR performance criteria for windows are based on NFRC-certified ratings and vary by climate zone. Source: ENERGY STAR, "What makes it ENERGY STAR?" (US EPA).
ENERGY STAR describes aluminum frames as durable, low maintenance and recyclable, with frame designs that typically include thermal breaks to reduce conductive heat loss through the metal. Source: ENERGY STAR, "What makes it ENERGY STAR?" (US EPA).
If your project needs ENERGY STAR or an energy-code rating, ask the supplier whether the exact product has NFRC-certified ratings; a factory test report alone is not the same thing.
China's national standard: GB/T 8478-2020
GB/T 8478-2020 "Aluminium windows and doors" is a current Chinese national standard, published on 2020-03-31 and in force from 2021-02-01. Source: GB/T 8478-2020 record, National Public Service Platform for Standards Information.
GB/T 8478-2020 fully replaces GB/T 8478-2008. Source: GB/T 8478-2020 status record, National Public Service Platform for Standards Information.
The standard covers classification and marking, requirements, test methods, inspection rules, marking and accompanying documents, packing, transport and storage of aluminum windows and doors. Source: GB/T 8478-2020 scope, National Library of Standards.
It applies to manually operated windows and pedestrian doors for exterior walls and interior partitions and to vertical roof windows; it does not apply to skylights, non-vertical roof windows, rolling shutters, revolving doors, or special windows and doors such as fire-rated, blast-resistant, escape and smoke-vent units. Source: GB/T 8478-2020 scope, National Library of Standards.
A GB/T 8478 report shows testing to the Chinese standard; if your project is specified to ASTM methods or NFRC ratings, ask for those reports separately.
US duties: frames vs finished windows
The US countervailing duty notice on aluminum extrusions from China includes in scope extrusions described at import as parts for products assembled after importation, such as window frames, door frames, solar panels, curtain walls or furniture. Source: Federal Register 91 FR 51662, FR Doc. 2026-16362 (Aug. 11, 2026), case C-570-968.
Finished merchandise fully and permanently assembled at the time of entry, such as finished windows with glass, is excluded from that scope. Source: Federal Register 91 FR 51662, FR Doc. 2026-16362 (Aug. 11, 2026), case C-570-968.
A finished goods kit is excluded, but including fasteners such as screws or bolts in the package does not by itself make a product a finished goods kit. Source: Federal Register 91 FR 51662, FR Doc. 2026-16362 (Aug. 11, 2026), case C-570-968.
The notice states that the written description of the scope is dispositive, not the HTSUS number. Source: Federal Register 91 FR 51662, FR Doc. 2026-16362 (Aug. 11, 2026), case C-570-968.
For rates and reviews see the anti-dumping guide, and confirm classification with your customs broker before you order.
Checklist before you place an order
These steps follow from the sources above.
- Write the required test methods (for example ASTM E283, E330, E331) and any energy rating into your purchase specification.
- Ask for test reports that match the exact profile series, size and glazing you are buying.
- If you need ENERGY STAR or code energy ratings, ask whether the product has NFRC-certified ratings.
- If the supplier quotes GB/T 8478-2020, treat it as the Chinese standard and ask separately for any reports your market requires.
- Decide whether you import finished glazed windows or frame parts, and confirm the US duty scope with your customs broker.
- Check the factory's registration with the factory check tool and model duties with the landed-cost calculator.
FAQ
What does ASTM E331 test on a sliding window? It tests resistance to water penetration with water applied to the outdoor face and exposed edges while the outdoor side is held at a higher static air pressure. Source: ASTM E331-00(2023), Scope and Significance and Use.
Is an ASTM E283 result from one window valid for a different window? ASTM says air leakage comparisons may not be valid unless the components tested are of essentially the same size, configuration and design. Source: ASTM E283/E283M-19, Scope and Significance and Use.
Who certifies energy ratings for ENERGY STAR windows? ENERGY STAR certified windows have their ratings independently tested and certified through NFRC. Source: ENERGY STAR, "What makes it ENERGY STAR?" (US EPA).
Is GB/T 8478-2020 still current? Yes. The National Public Service Platform for Standards Information lists GB/T 8478-2020 as current, in force since 2021-02-01. Source: GB/T 8478-2020 record, National Public Service Platform for Standards Information.
Do US duties on Chinese aluminum extrusions cover finished sliding windows? Finished windows with glass that are fully and permanently assembled at entry are excluded, but extrusions imported as parts for window frames assembled after importation are included. Source: Federal Register 91 FR 51662, FR Doc. 2026-16362 (Aug. 11, 2026), case C-570-968.
From research to a supplier shortlist
Suppliers are ranked from public records and our published methodology — we don't sell leads or take pay-to-rank. Confirm prices and certifications directly with the supplier via RFQ.