Welcome

With the first half of the year already behind us the year is moving as quickly as WERS is growing. We are in full swing now with new WERS ratings getting added to the database every day. We have grown from 2000 ratings to 4000 ratings within the first six months, with many more on the way.

WERS has applied to the AFRC to become the AFRC audit house, with myself performing the auditing of custom ratings. The process is moving well, the backlog of work has been finalised and additional work continues on a daily basis.

With WERS as the AFRC auditor the simulation cost for the company is kept down. As part of the WERS membership fees the custom rating audits are subsidised to help the industry continue to grow.

As WERS ratings and awareness increase, we look forward to working for the members, to help it grow even further.

Mike Palin
WERS Administrator

How the WERS Star Ratings Work

WERS is a scheme which awards a pair of star ratings to a window to provide the consumer with a simple scale with which to compare windows. One star rating is for heating performance and the other for cooling performance. The star ratings are on a 10-star scale much like the new, extended 10-star system that was recently announced by the Federal Government for electrical appliances. House energy ratings are also on a 10-star scale, using the software tools AccuRate, FirstRate5 or BERS Pro. However the factors contributing to window-rating stars are quite a bit more complex.

Appliance star ratings (e.g. for refrigerators) are based on how much energy the appliance uses when compared with a base case appliance. Like appliances, the WERS stars are based on the Annual Energy Performance (AEP) of the window but unlike appliances, there isn’t a simple annual energy figure, for that window on its own, that can easily be established.

A calculator of the AEP was developed by Dr Peter Lyons to take into account the impact of various characteristics of the window on the annualenergy use of a typical house for heating and cooling.

With the predicted energy use and compared to a benchmark house, a star rating can be calculated. All star ratings are a means of ranking a product against its peers – they are a relative measure not an absolute one.

Windows under WERS have been rated using NFRC procedures and protocols. The NFRC report generates results for U-Value, SHGC and VT for the whole window, including glass, frame and seals. The U-value relates to the insulation value of the window, with a lower U-value meaning better insulation. The SHGC is the Solar Heat Gain Coefficient and is the proportion of radiant solar heat that is able to pass through the window (directly and indirectly). The SHGC is a fraction between 0 and 1. The higher the SHGC, the more heat from the sun is able to pass through, as an example, a window with a SHGC of 0.78 allows 78% of heat to pass through (good in a cold climate) where as a window with a SHGC of 0.30 only allows 30% of heat through (more suited to a hot climate). VT is visible transmittance, as with the SHGC, the VT is a fraction . A window with a VT of 0.68 allows 68% of natural light to pass through. The other value that WERS repo-

rts to is the Air Infiltration value. This is a value generated from the AS 2047 testing. It is a number which shows how much air leaks in through the window when a 75Pa positive air pressure is applied. Air leakage through a window occurs around the seals and tracks of the window.

The AEP calculator takes the U-value, SHCG and Air Infiltration to predict the annual heat and cooling load in a typical house when that window is used. The predicted energy is thenused to determine the stars and percentage improvements compared to the base case window. The calculator generates both heating and cooling stars and heating and cooling percentages for the given window.

WERS is a scheme for comparing windows on a fair, unbiased and equal basis. For more information, and a wide range of WERS rated products, visit www.wers.net.

WERS Generics

There used to be a list of generics available on the website, where have they gone? Can I get a copy?

The WERS generics were available for WERS member companies that didn't have a custom rating done. There were issues with people using the ratings who weren't WERS members or weren't using WERS members' products.

In order to address this, we have created custom tables for all WERS members, even if they are using the "generic" values. A blank WERS generics table no longer exists. If you require energy ratings, go to the certified products section and download a company specific table. Any misuse of these tables will not be validated. ABSA now recieve a monthly update to the database, so any rating that is misused will be easily dicsovered.

If you need more information regarding this, please contact the WERS Office.