In Episode 4 of Smarter Glass, Better Living, I run a quick experiment that shows exactly why so many Kiwi homes feel cold, and why double glazing makes such a big difference.
If you’ve ever stood beside a window on a winter night and felt the chill pouring off the glass, that’s heat loss. And in older New Zealand homes, single glazing is one of the biggest culprits.Here’s what I’ve seen it do in real homes.
Why windows matter
In many pre 2007 homes, up to half of your heat loss can happen through the glass. That means:
- Rooms cool down faster
- Heaters work harder
- Power bills climb
- Condensation forms on cold mornings
So we set up a simple test to show what’s really going on.
The Experiment
We used:
- Two heat lamps (your indoor heat source)
- One single glazed pane
- One Metro Xcel Low E double glazed pane
- Radiometers to show how much heat gets through
When the lamps switch on:
- Behind the single glazing: the radiometer spins almost instantly
- Behind the double glazing: it barely moves
The difference is immediate. Single glazing lets heat escape. Double glazing slows it right down.
Why this happens
Heat moves through glass in three ways: conduction, convection, and radiation. Single glazing doesn’t do much to stop any of them. Double glazing adds an insulating gap, and Low E coatings reflect heat back where you want it.
The result:
• Warmer rooms in winter
• Less overheating in summer
• Fewer cold drafts
• Less condensation
• Lower energy use
Why single glazing struggles
Older homes with single glazing deal with:
- Cold glass surfaces
- Constant heat loss
- Crying windows and damp curtains
- Rooms that never quite warm up
It’s simply not designed for modern living
Why double glazing works
Double glazing adds:
- Two panes of glass
- An insulating air or argon gap
- A warm edge spacer
- Optional Low E coatings for even better performance
This combination keeps heat in, keeps cold out, and keeps your home more stable and comfortable year round.
Can you retrofit it?
Yes. Retrofit double glazing replaces the glass, not the frames. No cladding removed, no major renovation — just a smart upgrade for older aluminium or timber joinery.
See the experiment
If you want to see the difference for yourself, Episode 4 shows it in real time. It’s a simple demonstration, but it makes the point clearly: Double glazing keeps your home warmer, drier, and more efficient.
Want to know more, visit: retrodg.co.nz
