techy stuff

The Science

Various factors determine the thermal effectiveness of energy efficient windows. These include:

• thickness and type of glass used,
• number of layers of glass, 
• type of spacers used,
• material used for the frame, and
• quality of the seals around the frame

The space between layers of glass is filled with an inert gas, commonly argon or xenon, which slows down the movement of heat through the window.

Like insulation, the thermal efficiency of the whole window is measured by the U-Value. The lower the value, the better the window. Good window U-values range down to 0.6.

Application

Whilst triple glazing is becoming more and more important for very low energy buildings, significant savings can be made using double-glazing alone. 

If windows are being replaced during a renovation, regulations state that the new windows must be double-glazed with a U value of less than 3. It is easy to make the replacements even better again by using triple glazing; however, the cost will go up.