WEERS is New Zealand’s “Window Energy Efficiency Rating System” which gives you an accurate rating of the energy efficiency of your homes windows and doors.

WEERS Background

WEERS is New Zealand’s “Window Energy Efficiency Rating System”. The Window Association (now known as Window & Glass Association) has introduced a system  called WEERS – which is an accurate rating of the energy efficiency of the actual window or door you purchase.

The windows and doors you purchase are built to your exact requirements and the choices you make can change the energy efficiency rating.

WEERS Window Energy Efficiency Rating System logo

How does WEERS differ to other rating systems?

There are other window rating systems available worldwide with many of those being based on rating a standard window size and configuration.  This rating may be quite different to the window actually being purchased, leaving the customer unaware of the actual energy performance of their windows.

WEERS is an advanced window energy rating system that offers you an accurate rating specific to each window and door that you purchase. Every individual window will have its own unique rating even if they are similar sizes.

When you purchase a house lot of windows today, the window manufacturer can provide you with an R-value for the entire house lot which can be given to your Architect or Energy Consultant to use in whole-house energy calculations.

In existing windows, this isn’t quite so easy to determine as in most situations the original R-value of the frames is not available.  Calculations can be made based on the R-value of current framing options and is why our “What Changes” diagrams use the wording “achieve a WEERS equivalent rating”.

WEERS origins.

WEERS was developed by BRANZ in conjunction with the Window and Glass Association of New Zealand. EECA and MBIE have also been partners in the development.

The WEERS energy rating takes into account all of the materials that go into the construction of the window or door to ensure you are getting an accurate rating.  This includes the frame material, the various glass used in the double glazing (insulating glass units) and the specific combinations of components associated with these such as the spacer type used in the double glazing.

The WEERS rating process.

WEERS combines the thermal performance of all the frame components, the glass and the glazing method, also incorporating the configuration and size of the individual window to determine the thermal performance of the complete window as an R-value, and also as a WEERS star rating. The WEERS rating process determines which high thermal-performance windows qualify for Energy Star endorsement.

Software performs the calculations as each window is being quoted. Each component part has its own unique data. The software has been verified as complying with the requirements of international thermal modelling standards, and the WEERS processes are audited annually.

WEERS prerequisites.

Before being WEERS rated, windows and doors must meet the WGANZ requirements which include compliance with the New Zealand Building Code including B1 Structure, B2 Durability, and E2 External Moisture; NZS4211 Specification for the Performance of Windows; NZS4223 for glass selection and glazing, and IGUMA-EN1279 for testing insulating glass units.

Overseas ratings.

WEERS ratings are specific to the New Zealand climate using New Zealand climate conditions as determined by BRANZ and MBIE.

Thermal efficiency ratings from other countries, including Australia, USA, Canada and Europe are not easily comparable to New Zealand as each country has its own unique conditions. Working out the correct rating for New Zealand conditions requires specialist expertise, such as that provided by BRANZ, to determine the reliability of any overseas energy performance claim if they are to be applied for use in New Zealand.

Any other performance claim for windows or doors, such as equivalency to NZS4211, or NZS4223 must be independently verified before being accepted for use in New Zealand. WGANZ can facilitate such independent verification.