When you choose new windows and doors, you are trusting that they will perform as promised for decades. They need to keep heat in, keep weather out, resist forced entry, and operate smoothly year after year. But how do manufacturers prove that a product can actually do all of these things? The answer lies in a series of rigorous, independently verified tests that every product must pass before it can be installed in your home. Understanding what these tests involve gives you a clearer picture of what you are actually paying for when you invest in quality.
Weather performance testing
Weather performance is assessed under EN 14351-1, the European product standard for windows and doors. Three properties are measured, each on a classified scale.
Air permeability measures how much air leaks through the window or door when it is closed. The product is mounted in a test rig and subjected to increasing air pressure. The amount of air that passes through the frame, seals, and junctions is recorded at each stage. A higher classification means less air leakage, which translates directly to fewer draughts and lower heating costs in your home.
Water tightness measures how well the product resists water penetration under pressure. Water is sprayed against the external face of the window while air pressure is applied to simulate wind-driven rain. The test increases in intensity until water penetrates the assembly. For coastal and exposed properties, a higher water tightness classification is essential.
Wind resistance tests the structural integrity of the window under sustained wind loading. Positive and negative pressure cycles are applied to simulate the forces a window experiences during high winds. The product must maintain its structural integrity, and the deflection of the frame must remain within defined limits. This matters in Ireland’s climate, where winter storms regularly produce wind gusts that place significant pressure on the building envelope.
Security testing
PAS 24:2022 is the current enhanced security standard for windows and doors. It is a pass-or-fail test designed to replicate the methods an opportunist burglar would use to break into a home.
The testing sequence includes mechanical loading, where significant force is applied to the frame and hardware to test whether the window can be prised open. It includes hard and soft body impact, simulating blunt force strikes against the glass and frame. And it includes manual attack, where a tester uses a prescribed set of tools to attempt to manipulate hardware, cut through materials, and remove glazing. For doors, additional tests cover cylinder vulnerability and letterplate security.
Every Fairco window and door is independently certified to PAS 24:2022, which means every product in the range has been subjected to and passed this full testing regime.
Thermal performance testing
The thermal performance of a window is expressed as a U-value, measured in W/m²K. A lower number means less heat passes through the assembly. U-values are determined through a combination of laboratory testing and calculation, taking into account the glass, the gas fill, the spacer bar, the frame material, and the way these components interact at junctions.
Whole-window U-values are important because they reflect the performance of the complete assembly, not just the centre of the glass. The frame, the edge of glass, and the spacer bar all influence the final number. This is why products with warm-edge spacer bars, multi-chambered profiles, and triple glazing consistently outperform products that may have the same centre-pane glass but weaker detailing at the edges and frame.
Cycle testing
Windows and doors are opened and closed thousands of times over their lifetime. Cycle testing simulates this by operating the hardware repeatedly under controlled conditions, checking that handles, locking mechanisms, hinges, and friction stays continue to function correctly after extended use. This is particularly important for tilt-and-turn windows and multi-point locking systems, where the mechanism is more complex, and the long-term reliability of the hardware directly affects both security and ease of use.
From the laboratory to your home
Testing proves what a product can do under controlled conditions. But the results only hold true if the product that arrives at your home is built to the same specification as the one that was tested. This is where manufacturing quality and consistency become critical.
Because Fairco controls design, manufacture, and installation from our Antrim facility, the product installed in your home is built to the same tolerances, with the same components, and to the same specification as the product that passed every test. That chain of accountability is what separates a test certificate from real-world performance.
If you would like to understand more about how Fairco products are tested and certified, book a free consultation or visit our showrooms to see the quality of construction firsthand.
