When it comes to choosing the right type of glass for your doors and windows, there are a number of considerations that can influence your decision...

• The climate where you live
• The location of the building
• The placement of the windows or doors
• The purpose of the windows or doors

Arriving at a decision in glass selection will require a balance between light, heat, and fading control. The more light you want coming in, the less you can control heat and fading.

There has been a gradual shift to improving the energy efficiency of buildings. This has resulted in a need to replace the use of single glazing of doors and windows with insulating glass units.

An insulated glass unit (IGU) consists of two or more panes of glass sealed together with an air gap between them. The air gap gives the IGU its ‘insulating’ properties by separating the outside pane from the inside pane.

The effectiveness of IGUs can be improved by filling the air gap with Argon as well as by using Low E (low emissivity) glass or tinted glass.

Double-glazed units are the most widely available type of IGU. Double glazing offers two fundamental benefits – heat retention in cold conditions, and sound dampening from external sources. 

Here in New Zealand, most homes are now required to have double glazing for energy preservation purposes.

Glass selection allows for variations in pane thickness, glass surface coatings, glass colourants, IGU air gap width, IGU gas fill etc. There are also options for safety glass, with the choice being between toughened glass and laminated glass.

The images below provide a visual comparison of the performance of the most popular glass options available.

Metro Performance Glass (aka Metro GlassTech) Double Glazing Insulating Glass Units (IGUs) are manufactured to high quality control procedures and have been tested by BRANZ and comply with the most recent IGU durability tests, BS 5713:2002: Part 1 & 2 (EN 1279).

Metro Performance Glass is so committed to quality it tests three times more often than NZ industry requirements.
The units have a 10 year warranty and the full written warranty can be provided with the units.

The warranty is subject to some conditions, the key items of which are as follows:

• Units must be handled and stored according to instructions.
• Units must be glazed in accordance with our instructions.
• The glazing system must not trap water.
• Incompatible sealants or glazing materials must not be used.
• The units must not be broken or altered in any way.

Please refer to Metro's Double Glazing (IGU) Warranty for further information.
There you'll also find instructions on the Handling, Storage and Glazing of Insulating Glass Units.