Kia ora folks! If you’re still living with single-glazed windows, chances are you’re dealing with cold mornings, ‘crying windows’, and a power bill that makes you wince. The good news? You don’t need to rip out your entire window system to fix it. Retrofit double glazing is one of the best bang-for-buck upgrades you can make to your home, and it works beautifully in both aluminium and timber joinery.
Why it matters
According to MBIE, windows can account for 35–50% of heat loss in a single-glazed home with poor insulation. That’s a huge amount of warmth, and money, leaking straight out. Retrofit double glazing fixes this by upgrading the glass inside your existing frames, with no full window replacement needed.
What is retrofit double glazing?
In plain English, it’s swapping your single pane for a Double Glazed Unit (DGU), two panes sealed together with air or argon gas between them. Add a Low-E (low-emissivity) coating and warm-edge spacers, and you’ve got a seriously effective thermal barrier:
- Low-E glass reflects heat back into your home in winter and reduces heat build-up in summer.
- Argon gas fill improves insulation between the two panes.
- Warm edge spacers reduce heat transfer at the edges of the unit.
How a double-glazed unit works
Aluminium joinery
Most Kiwi homes built from the 1970s onward have aluminium frames, and they’re very well suited to retrofit double glazing. The existing single glazing is removed and a new factory-sealed unit fitted using the correct packers, seals and glazing tape. Good workmanship is everything here.
Retrofit double glazing in aluminium joinery
Timber joinery
Got a villa, bungalow, or character home? Timber actually insulates better than standard aluminium, so retrofit double glazing performs exceptionally well in timber frames, while preserving the character of your home.
Do you need a building consent?
In most cases, no. If you’re keeping existing frames in place and upgrading the glass like-for-like, building consent is generally not required. If you’re ever unsure, just ask the team at Retrofit Double Glazing by Metro Glass.
Choosing the right glass for your region
The bottom line on energy savings
Upgrading to Metro’s Low-E double glazing can deliver up to 79%* better heat retention and up to 74%* reduction in summer solar heat gain through your windows, less reliance on heat pumps and heaters, and lower power bills over time.
*Compared to 4mm single glazing.
A warmer, brighter living room
Ready to see it in action?
Watch an episode of Smarter Glass, Better Living, then talk to the team at Retrofit by Metro Glass about the right specification for your home. Peter Wolfkamp, Resident Builder.
