Windows

Performance rating

The Manitoba Building Code does not have minimum standards for the energy efficiency windows.

However, a new voluntary standard called the Energy Rating (ER) has been developed by the Canadian Standards Association to help consumers and builders compare the thermal performance of windows and patio doors.

A window s ER rating is a measure of its overall performance based on three factors

1. solar heat gains;
2. heat loss through the frames, sashes, spacers and glazing; and
3. air leakage heat loss.

The ER value is measured in watts per square metre. It is calculated as the difference between the heat gains and heat losses of the window over the entire heating season for an average Canadian home and location.

When shopping for windows, always ask if the product you are considering has an energy rating. Window ER numbers generally range from -50 to about +15. The higher the ER number, the better the window performance:

• A window with an ER of –30 (i.e. a standard double-glazed window) would be considered a substantial energy loser.
• A window with an ER number of 0 is neutral in energy consumption — it contribute as much solar heat to the house over a heating season as it loses.
• Any window with a plus number actually adds more heating energy to a home than it loses.

Windows and your R-2000 Builder

R-2000 Builders are trained about window types, performance, placement and orientation. They can provide you with important guidance and help ensure that that the design of your new home will meet the R-2000 energy performance target.

Also important is that R-2000 Builders apply their special training and attention to detail when installing windows and sealing around the frames to minimize air leakage.