For any buyer planning to source casement windows from a manufacturer and sell them into the European market, CE certification is not optional paperwork — it is a legal requirement that determines whether the product can be placed on the market at all. As a casement window supplier working with international builders and distributors, we are often asked the same questions: what does the CE mark actually prove, which tests apply to aluminum casement windows, and how can a buyer verify that a Chinese factory truly meets these standards? This guide answers those questions clearly and practically.
The CE mark is the manufacturer's declaration that a construction product conforms to the applicable European legislation. For windows and external pedestrian doorsets, this is governed by the Construction Products Regulation (CPR 305/2011). By affixing CE, the manufacturer takes responsibility that the product's declared performance matches what is stated in its Declaration of Performance (DoP). Importantly, under the CPR the CE mark can only be applied once a valid DoP has been drawn up — the two go hand in hand.
The harmonized European product standard for windows and external pedestrian doorsets is EN 14351-1. This standard defines both the essential product characteristics that must be declared and the test methods used to measure them. When a factory certifies aluminum casement windows, the testing program must cover a defined set of performance characteristics — the most important of which are summarized below.
This measures how much air leaks through the closed window under pressure, and is graded from class 1 (low tightness) to class 4 (very good tightness). Higher classes mean lower air loss, better energy efficiency and greater comfort. For casement windows, a tight multi-layer sealing system is what pushes performance toward classes 3–4.
A window is exposed to wind-driven rain, and this test confirms how much water pressure the product can withstand before leakage appears. Correct drainage design, proper gasket compression and continuous sealing are decisive. A well-engineered casement system typically scores 6A–9A, meaning it resists significant rain pressure without letting water inside.
This test simulates the pressures a window faces in high wind and storms, assessing both frame deflection and load capacity. The result is expressed as a pressure class (for example 1600 Pa or class C5 in certain systems). Strength here depends heavily on profile wall thickness, corner reinforcement and sash design.
The U-value (expressed as W/m²K) tells buyers how well the complete window — frame, glass and gaskets — insulates against heat loss. Lower values mean better insulation. Modern thermal-break aluminum casement windows can reach U-values down to around 1.3–1.6 W/m²K depending on the glass specification, which is why a genuine multi-chamber thermal break system matters so much.
The standard also covers airborne sound insulation, the load-bearing capacity of safety devices (such as fall protection and window restrictors), the force needed to open and close the window, and the potential release of dangerous substances. A complete certification therefore verifies not just weather performance but also operational safety and indoor comfort.
There are three pillars to a valid CE certificate for aluminum casement windows:
Initial Type Testing (ITT). Representative samples — including the complete frame, glazing, hardware and sealing strips — are sent to an accredited laboratory and tested against the EN standards described above. The samples must reflect the actual production state and cover the most demanding combinations, such as the largest size, the thinnest profile and the largest glass area, so the declared values remain valid across the product range.
Factory Production Control (FPC). The factory must have a documented quality system that keeps ongoing production consistent with the tested samples — controlling profile extrusions, thermal break assembly, corner joints, gaskets and hardware fitting. For most window suppliers this is evaluated under System 3 (product type testing by an independent body) or System 4 (factory self-declaration combined with FPC).
Declaration of Performance (DoP). Once testing and production control are in place, the manufacturer issues a DoP that lists every declared characteristic and its measured value. The CE mark accompanies this declaration and is fixed to the product or its label before it is placed on the market.
A CE certificate is only as reliable as the process behind it. When evaluating an aluminum casement window factory, buyers should look for the engineering decisions that make the test results repeatable rather than one-off. At ALPES, we build this into the product itself:
Our casement windows are extruded from 6060-T66 aluminum profiles with thicknesses from 1.8mm to 2.0mm, meeting and exceeding new national standards. Heat loss is controlled with PA66GF25 multi-chamber thermal break systems, allowing low U-values such as 1.6 on the C120 outward-opening system and 1.7 on the C116 series. Sealing performance is reinforced with triple sealing strips, injection-molded structural adhesive, glued corner brackets and contiguous corner sealing, supporting strong air permeability and water tightness classes. High-strength corner reinforcement and collision-resistant profiles provide wind load stability, while hardware from trusted European partners — ROTO, Winkhaus, CMECH and Wehag — keeps opening cycles smooth and safety devices reliable over years of use.
Because these features are engineered into the standard product rather than treated as optional add-ons, a buyer who commissions CE testing from our factory can be confident that a production unit will reproduce the performance of the certified sample. It is this combination of material quality, controlled manufacturing and consistent production control that separates a printed certificate from a genuinely certifiable product.
Before committing to volume, verify that the certificate and DoP use the exact product designation and dimensions you intend to buy, confirm which performance classes are declared, and ask the factory to explain how ongoing Factory Production Control is maintained. Request the test laboratory's accreditation details and, where possible, a sample for your own verification. A transparent supplier will share these documents openly and help you map declared values to the specific project requirements of your market.
Getting aluminum casement window CE certification right may add work up front, but it removes the biggest obstacle to selling in Europe: proving the product performs as claimed. When your factory combines genuine material quality with rigorous testing and disciplined production control, the CE mark stops being a hurdle and becomes a clear commercial advantage — for you and for the builder who installs the windows on site.
