It is useful to understand the standards before you select your new windows. The A440 standard establishes the minimal performance criteria for windows. Testing conducted according to this standard reveals the true performance of windows. Manufacturers must measure the performance of their windows through tests performed by an accredited independent laboratory, recognized by the Canadian Standards Council. Windows are classified according to different ratings: A1 to A3 ratings measure airtightness; B1 to B7 guage watertightness; and C1 to C5 ratings correspond to wind resistance. The better performing windows are rated higher.
The airtightness test measures the level of air infiltration when air pressure equaling the force of a 40 km/h wind is applied to the window. The watertightness test consists of applying different levels of air pressure while shooting a jet of coloured water on the exterior surface of the window, simulating the wind that accompanies rain precipitation. The wind resistance test determines the sturdiness of a window?s frame and mullions by measuring the pressure that the window can support without breakage, weakening, or permanent deformation.
Other tests can also be done on windows. Testing for condensation resistance calculates a window?s temperature index. It measures the temperature on the glass and on the sill, when it is 20º inside and – 30º outside. The higher the index, the higher the room?s humidity level can be without causing condensation on the surface of the window. You should also consider the energy efficiency of a window.