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Warmer in Winter,
Cooler in Summer —
& UV Protection
Without Replacing Your Windows
Thermal Glass Coat is a clear insulation coating applied directly to your existing windows to reduce heat loss. It blocks up to 99% of UV and reduces heat loss by up to 50%, keeping rooms warmer in winter and cooler in summer — without the cost or disruption of retrofit double glazing or replacing your joinery. It’s a proven double glazing alternative for homes and businesses across Auckland, Waikato, Bay of Plenty and Hawke’s Bay.
Applied by trained technicians in half a day to two days, depending on the size of the job. Guaranteed for 10 years. Call 0274 810 686 or email admin@thermalglasscoat.co.nz.
What it is
Thermal Glass Coat is a liquid nanotechnology coating that bonds chemically to the surface of your existing glass, forming a durable, virtually clear layer about seven microns thick. It uses Sol-Gel and nano technology originally developed in Japan and has been used in homes and commercial buildings across Japan, Malaysia, Dubai, Abu Dhabi, Australia and New Zealand for over a decade.
Unlike stick-on window film, it is a bonded coating — not a laminate — so it will not bubble, peel or delaminate. It has only a very slight blue/green tinge, so it does not change the look of your windows or reduce your privacy, and it lets natural light through while cutting the invisible heat and UV.
How it works
Most of the warmth you feel from the sun — and the heat that escapes your home in winter — travels as infrared radiation, not warm air. Thermal Glass Coat works like a mirror for that infrared: it reflects infrared energy back toward where it came from, keeping heat on the side of the glass it started on.
There are two different kinds of infrared, and the coating handles both:
- In summer, it reflects incoming near-infrared (solar) heat away before it enters, so rooms stay cooler and heat pumps and air conditioners work less.
- In winter, it reflects your home’s own far-infrared heat back inside — the long-wave warmth radiating off your heater, walls, furniture and our bodies — instead of letting it escape to the cold glass. This is the low-emissivity (“Low-E”) behaviour that keeps rooms warmer.
- Year-round, it blocks up to 99% of UV rays, protecting furniture, carpets, curtains, artwork and family photos from fading. Because even standard double glazing blocks little UV, we’re often asked to apply the coating over existing double glazing purely for UV and fading protection.
- It can also help reduce condensation by keeping the inner glass surface closer to room temperature.
So it isn’t doing two opposite jobs — it’s one consistent behaviour, reflecting infrared back to its source. The season simply changes which direction the heat is coming from. Because it lowers how much heat moves through the glass, your heating and cooling run more efficiently — which is where the energy savings come from.
The coating reduces heat transfer rather than stopping it completely, because some heat still passes through the glass itself by conduction.
Results you can expect
- Winter indoor temperatures increased by 5–10°C on treated glass.
- Summer indoor temperatures reduced by 3–10°C.
- Up to 50% less heat loss through treated windows.
- Up to 99% of UV blocked.
- Coating hardness of 4.5H (window films are typically ~3.5H; bare glass is ~7H).
- 10-year guarantee against cracking, bubbling, peeling and delaminating.
Where we work
Thermal Glass Coat serves homes and commercial buildings in Auckland, the Waikato, Bay of Plenty and Hawke’s Bay (Hastings/Napier). Application is carried out by trained local technicians with minimal noise, mess and disruption — most jobs are completed in half a day to two days, depending on the size of the job.
Glass coating vs window film
Both a glass coating and a stick-on window film are optical treatments applied to your existing glass. Both cut infrared heat and UV, both are “always on,” and both are pitched as alternatives to double glazing. On single glazing, both also share the same limit: they reduce radiant heat, but some heat still transfers by conduction through the glass itself. We say that openly — it’s true of any glass treatment.
The real difference is how they’re made and how they last.
| Thermal Glass Coat (bonded coating) | Stick-on window film (adhesive laminate) | |
|---|---|---|
| How it attaches | Chemically bonds to the glass as a ~7-micron solid layer | Held on by adhesive as a separate laminate sheet |
| Edge failure over time | Won’t bubble, peel or delaminate | Common failure mode — lifts, bubbles and peels at edges |
| Clarity | Very slight tint; view essentially unchanged | Many films tint or add a reflective sheen |
| Surface hardness | ~4.5H — more scratch-resistant | ~3.5H — softer, scratches more easily |
| UV blocked | Up to 99% | High-end films block UV well; cheaper films are often UV-only |
| Heat loss | Up to 50% less through the glass | Varies by product; darker tint films reduce heat loss more |
| Guarantee / lifespan | 10-year guarantee against cracking, bubbling, peeling, delaminating | Typically 3–10 years; often replaced as it degrades |
| Application | Applied by trained technician; durable, long-lasting finish | DIY or installed; removable |
Where window film has the edge — and we’ll say so: some films are cheaper up front, are removable if you’re renting, and come in heavy-tint, mirrored-privacy or safety-glass versions that a clear coating doesn’t offer. If dark privacy tint or shatter protection is your main goal, a film may suit you better. If you want a permanent, near-invisible improvement to the glass that won’t peel and is guaranteed for 10 years, that’s where the coating wins.
How it compares to other options
| Option | Relative upfront cost | Reduces heat loss | Cuts condensation | Blocks UV | Install disruption | Changes appearance / view | Typical lifespan |
|---|---|---|---|---|---|---|---|
| Thermal Glass Coat (bonded glass coating) | Low–moderate | Yes — up to 50% less heat loss through the treated glass | Yes — helps keep inner glass warmer | Yes — up to 99% | Low — no building work | Very slight blue/green tinge — view and privacy unchanged | 10-year guarantee |
| Stick-on window film | Low | Low–moderate — darker films more effective | Limited | Yes (most films) | Low — DIY or installed | Often tints; can haze/peel over time | 3–10 years (can peel/bubble) |
| Retrofit double glazing | High | Highest — biggest improvement in glass U-value | Yes — strong | Limited — standard glazing blocks little UV | High — joinery work, days | No, but frames may need modifying | 15+ years |
| Full window replacement (new thermally-broken joinery + double glazing) | Highest | Highest overall (glass + frame) | Yes — strongest | Partial — depends on glass spec | Highest — major build work | Yes — new frames | 20+ years |
| Thermal / lined curtains | Low–moderate | Moderate — helps, but leaks around edges and top | Limited — can trap moisture at the glass | No (fabric-dependent) | Low — no building work | Yes — covers the window when closed | 5–15 years |
| Do nothing | None | None | No | No | None | None | — |
Reading the table: Double glazing and full replacement give the biggest thermal improvement but cost the most and involve building work. Curtains help but only when closed and leak heat at the edges. Among the two glass treatments — coating and film — the coating is the more durable and lower-maintenance of the two, which is the choice most buyers are actually weighing up.
What our customers say
Since the treatment was applied, the heat retention is amazing. I lit the fire on the first night — usually it struggles to provide warmth, but within 40 minutes I was in a t-shirt. My home has been transformed.
— Jennie, north-facing 1980s home (single glazed)
We first had our dining room windows coated to protect the curtains from UV. We were so impressed — and noticed how much warmer the house was in winter — that a year later we had the bulk of the house done. We can unreservedly recommend it.
— Karl Wassilieff, Ashhurst
Thank you and the team so much for such a fantastic job. We’ve noticed a marked difference — it’s a pleasure coming home now.
— Hannah H, Wellington
Our north-facing CBD apartment was unbearable in summer and the air conditioner couldn’t keep up. Now the aircon can actually do its job and it’s a pleasant place to be. The UV protection for our paintings and furniture is an added bonus.
— Roger & Ivy, Auckland CBD
Read more reviews on our Testimonials Page
Get a free assessment
Want warmer winters, cooler summers and lower power bills — without replacing your windows? Call 0274 810 686 or email admin@thermalglasscoat.co.nz for a free assessment in Auckland, Waikato, Bay of Plenty or Hawke’s Bay.
Frequently Asked Questions
It sounds like a contradiction, but it isn’t. The coating works like a mirror for infrared heat, reflecting it back toward where it came from. In summer, the sun’s heat is near-infrared coming from outside, so it’s reflected away and rooms stay cooler. In winter, your home’s warmth is long-wave far-infrared radiating off your heater, walls, furniture and the people inside, and the coating reflects that back inside instead of letting it escape — the low-emissivity behaviour that keeps rooms warmer. It’s one consistent behaviour; the season just changes which direction the heat is coming from. Some heat still passes through the glass by conduction, so it reduces heat transfer rather than stopping it completely.
No single coating fully matches double glazing’s U-value improvement, and we say so openly. Thermal Glass Coat’s strength is that it targets radiant (infrared) heat and UV directly, installs in as little as half a day with no building work, and costs a fraction of retrofit glazing — making it the practical choice when double glazing is too expensive or disruptive.
Yes. Thermal Glass Coat is applied to your existing single glazing and reduces the infrared heat passing through it. Some heat still transfers by conduction through single glass, so we’re happy to advise where a coating gives the best return for your specific windows.
No, not noticeably. Once applied the coating is virtually clear, with only a very slight tint most people don’t notice. It doesn’t reduce your privacy or block natural light — it only cuts the infrared heat and UV you can’t see.
Yes — Thermal Glass Coat blocks up to 99% of UV, the main cause of fading in floors, furniture, curtains and artwork. This is one area where standard double glazing offers little protection, so we’re often asked to apply the coating over existing double-glazed windows purely for UV and fading control.
Thermal Glass Coat is guaranteed for 10 years against cracking, bubbling, peeling and delaminating. Because it bonds chemically to the glass rather than sticking on like film, it won’t lift at the edges over time. After 11+ years of applications in New Zealand we have had no instances of the coating breaking down, and in Japan it has been in use for 15+ years with no signs of breakdown.
Most homes are completed by a trained technician in half a day to two days, depending on the size of the job, with minimal noise and mess and no building work. You may need to move some furniture away from the windows.
Yes, it can help — but it will not stop condensation. By keeping the inner surface of the glass closer to room temperature, the coating reduces how much moisture condenses on your windows. How much depends on your home’s humidity and ventilation.
Both are optical treatments on your existing glass, but a coating bonds chemically to the glass while film is a separate laminate held on by adhesive. The bonded coating is virtually clear, harder-wearing (about 4.5H vs film’s ~3.5H), and won’t bubble, peel or delaminate at the edges — the most common way stick-on film fails. Film can be cheaper up front and comes in heavy-tint or removable versions, so it may suit renters or anyone wanting dark privacy tint.
Some window films reduce radiant heat and UV, but results vary a lot by product — darker tint films are more effective at reducing heat loss, while cheaper films are often UV-only. High-end films give thermal and UV performance similar to Thermal Glass Coat, though the coating is usually lower cost and more durable. On single glazing, heat still transfers by conduction through the glass regardless of the film. A bonded glass coating works on the same principle but is more durable. We’re happy to give you an honest assessment of what either can realistically achieve on your specific windows.
We serve Auckland, the Waikato, Bay of Plenty and Hawke’s Bay.
Call 0274 810 686 or
email admin@thermalglasscoat.co.nz for a quote.