Window Energy Rating System
The Window Energy Rating System was established in 1995 to give ratings and standards to windows and doors in Australia.
Windows and doors sold in Australia have to be tested to our harsh climate. Ratings can be found on Wers.net under residential certified products. Below is a sample of Inframe Glazing Systems Ratings.
There are three ways that windows and doors are tested: testing at an independent facility (the best), computer simulated (next best) and using overseas or other manufacturers ratings. It is clear on the ratings what has been used to test the windows. Those that use other's ratings have it noted as generic on the title. Those that have computer simulated often have an air infiltration rating of 0.5.
What do the ratings mean?
Uw is the rate of heat loss of a window assembly. The lower the uValue the better its insulating properties. The best rating is using the whole window. Ratings range from 2.0 to 10.0. Uw is the whole window, UC centre of glass and UF is frame.
SHGC – how well a product blocks the heat caused by sunlight. The fraction of incident solar radiation admitted through a window, both directly and absorbed and released inward. Between 0 and 1. Lower the rating the less solar heat gain.
VT – how much light comes in through the window. between 0 and 1 – the higher the rating the more light comes through
Air infiltration (leakage) on a test report. The lower the air infiltration figure the less air will pass through cracks in the window or door assembly.
How is the testing done?
AS 2047 performance test is undertaken at an independent facility
It is the mandatory minimum specification
for windows and doors used in Australia it includes compliance to the Glass
Standard AS 1288.
The following performance tests are undertaken to verify product performance claims.
AS 4420.2 Deflection Test - positive and negative wind pressures are applied to the face of the window to test the maximum deflection under wind load.
AS 4420.3 Operating Force Test - to verify that an opening sash is capable of opening and closing without undue effort.
AS 4420.4 Air Infiltration Test - the air leakage of a window is tested to ensure energy and acoustic efficiency.
AS 4420.5 Water Penetration Resistance Test - this test is designed to ensure no water leaks through the window into the building.
AS 4420.6 Ultimate Strength Test - negative and positive wind pressures are applied to the window to at least 1.5 times the design wind pressure to ensure it does not fail in unusual wind conditions.
The following performance tests are undertaken to verify product performance claims.
AS 4420.2 Deflection Test - positive and negative wind pressures are applied to the face of the window to test the maximum deflection under wind load.
AS 4420.3 Operating Force Test - to verify that an opening sash is capable of opening and closing without undue effort.
AS 4420.4 Air Infiltration Test - the air leakage of a window is tested to ensure energy and acoustic efficiency.
AS 4420.5 Water Penetration Resistance Test - this test is designed to ensure no water leaks through the window into the building.
AS 4420.6 Ultimate Strength Test - negative and positive wind pressures are applied to the window to at least 1.5 times the design wind pressure to ensure it does not fail in unusual wind conditions.
Before you buy any window or door, ask the supplier to see evidence of these tests. This will give you an assurance that you are buying windows and doors suitable for our climate.
Information from wers.net, awa.org.au
