What is retrofit double glazing?

What is retrofit double glazing?

Warm, light-filled comfortable living

  • Retrofitting is the process of upgrading your single glazing to new double glazing.

  • Choosing to retrofit can help you save on your renovation budget. Instead of completely replacing your window (glass and frame) which can be expensive, we replace your existing single glazed glass with a new factory sealed energy efficient double glazed unit, making retrofit a more affordable choice.

  • Our process involves making minor adjustments to the frame (such as a new aluminium or timber bead) to account for the new double glazing unit. The aesthetics look virtually the same allowing you to retain the character of your home.

  • Our double glazed units are factory sealed and then installed onsite. The process is relatively quick and hassle-free, leaving you to enjoy the comforts of your new double glazing.

  • You can combine our high performance Low E technology with your double glazing for the ultimate energy efficient solution:

  • Using our high performance Low E technology with your double glazing means there is less need for heating and cooling appliances, helping you reduce energy consumption and power bills.

    • For example, with our advanced Low E technology you can get up to 79%* better heat retention compared to single glazing, keeping your home warmer and drier in winter.

    • If you live in areas prone to overheating in the hot summer months we have a solar control glass option that can reduce up to 63%* of the sun's heat, helping keep your home cooler in summer.

  • Other lower-cost alternatives may be confused with Retrofit double glazing. Retrofit double glazing is a permanent replacement for single glazing, not a “clip-on” addition. It is a factory-sealed double glazed unit (as would be used in a new build), fitted into your existing frames. Unlike a clip-on solution, our double glazed units are purpose-built and able to be tailored for each individual homes needs.

*compared to single glazing

The diagram below shows an example of a before and after retrofit double glazed window in an aluminium frame.

Diagram of heat loss prevention from double glazed windows

  • Double glazing is an insulated glass unit (IGU) assembled and sealed in a controlled factory environment.

  • Double glazing is commonly used in windows and doors and is made up of two panes of glass separated by a spacer. The space between the glass is typically filled with air or an inert gas like argon.

  • What does this mean for my home?  Upgrading to Retrofit double glazing can provide better thermal insulation keeping your home warmer in winter and cooler in summer, allowing you to have a more consistent and comfortable temperature year-round.

  • Our double glazed units are locally processed in our New Zealand plants and are distributed across the country.

  • Our Retrofit double glazed units are also regularly tested by BRANZ and are compliant with EN1279.

  • We will also ensure everything we quote is compliant with the New Zealand Standards for Glazing in Buildings, including the safety requirements for human impact & safety from falling.

  • All of our Retrofit double glazed units come with a 10-year warranty.

The diagram below shows an example of what a double glazed unit looks like:

Detailed illustration of Metro Low E Double Glazed Unit

  • Low E glass is short for Low Emissivity glass.

  • Low E glass is aimed to improve energy efficiency, with a special coating that lets in visible light while reflecting heat (increasing the insulation) to maintain indoor comfort levels.

  • Our range of Low E glass is tailored to New Zealand conditions, offering a variety of performance benefits to cater to your specific priorities.

  • Low E can reduce heat loss by up to 79% (compared to single glazing) which can help keep your heating bills down.

  • If overheating is an issue in the hot summer months, our solar control Low E range can help reduce solar heat gain by up to 63% (when compared to single glazing).

  • Based on your specific needs we can customise a Retrofit double glazed solution incorporating Low E glass that provides an ultimate home performance upgrade.

The diagram below shows an example of how Low E technology works with your double glazing.

Diagram of Low E double glazing

  • Our solutions are purpose built for each home. Most Kiwis retrofit their homes for a warmer, drier, more comfortable living environment.

  • Retrofit double glazing, especially when Low E glass is selected, has many benefits, check them out below:

View benefits

We can retrofit (double glazing  as a replacement for single glazing) into most aluminium and timber window frames. Click which frame type you have at home to view the process of how we retrofit aluminium and timber windows:

Aluminium Timber

If you have experienced the benefits of standard double glazing but want better performance or to change the aesthetics of your windows, we can provide an option to “reglaze”. We can upgrade your standard/classic double glazing to a high performance Low E double glazing option, giving you the ultimate performance upgrade.


We have a range of double glazing options to suit your priorities. Each solution is customised and tailored to each home. View our range by clicking below

View range
Couple talking in home, while looking at double glazed windows online

Is retrofitting right for my home?

We understand that each home is different, our expert Retrofit consultant will assess your home, and recommend a tailored solution for you and your budget.

Get a free quote

Winter promo is on now use promo code WINTER2024! We have two deals - you choose! Get a discount or a bonus performance glass upgrade. Plus all accepted quotes from now until the 31st Aug go into the draw for a chance to win a $5,000 Travel voucher. Request a free quote here. Terms apply.