It is the single most common question we get on the phone: should I pay extra for triple glazing? Showroom sales teams tend to push triple as automatically better. After fitting A-rated uPVC windows in over 5,247 Irish homes since 2003, here is the honest answer — with real 2026 prices, U-values and payback maths for a Dublin, Kildare or Wicklow home.
The short answer: For most Irish homes built 1970–2010, A-rated double glazing is the smarter spend — it pays back in 7–10 years versus 18–22 for triple. Choose triple for deep retrofits, new builds targeting BER A2, north-facing bedrooms and exposed or elevated sites. Triple adds ~€150–€200 per window (U-value 0.8 vs 1.4 W/m²K). Both qualify for the SEAI grant (up to €5,600). Best value on many homes: a mixed spec.
What is the difference between double and triple glazing?
Double glazing has two panes of low-E glass separated by an argon-filled cavity; triple glazing adds a third pane and a second cavity. That extra pane is what drops the heat loss: an A-rated double-glazed unit achieves a U-value of about 1.4 W/m²K, while triple glazing reaches roughly 0.8 W/m²K — around 35–40% less heat lost through the glass. Both carry the A Window Energy Rating and both meet Part L of the Building Regulations.
Is triple glazing worth it in Ireland?
For most Irish homes, no — A-rated double glazing is the better financial decision. Triple glazing only pays back its premium over double after roughly 18–22 years; double pays back in 7–10. The reason is that windows are rarely the biggest heat-loss path in an older Irish home. In a 1970s Dublin semi with uninsulated cavity walls, you will lose far more heat through the walls than the windows — fix the walls and attic first. Check your current BER before deciding where the money is best spent.
Double vs triple glazing compared
| Feature | Double glazing | Triple glazing |
|---|---|---|
| Panes / cavities | 2 panes, 1 cavity | 3 panes, 2 cavities |
| U-value (typical) | 1.4 W/m²K | 0.8 W/m²K |
| Heat loss vs double | Baseline | ~35–40% lower |
| Added cost per window | — | +€150–€200 |
| 10-window semi (fitted, ex VAT) | €6,000–€8,000 | €7,500–€10,000 |
| Payback period | 7–10 years | 18–22 years |
| SEAI grant eligible | Yes (A-rated) | Yes (A-rated) |
| Best for | Like-for-like upgrades, south-facing rooms, budget | New builds / BER A2, deep retrofits, north-facing, exposed sites |
When should you choose double glazing?
Spec A-rated double glazing for:
- Standard like-for-like window replacements on homes built 1970–2010.
- South-facing rooms, where solar gain does useful work.
- Listed buildings and conservation areas (Georgian Dublin, parts of Dún Laoghaire and Bray) — often as timber-effect sliding sash.
- Budget-led upgrades where €600 per window is the ceiling, and rentals or investment properties.
When is triple glazing worth the extra?
Spec triple glazing for:
- New builds targeting BER A2 or better.
- Deep retrofits where you are also insulating walls and floors.
- North-facing bedrooms, where heat loss is worst.
- Exposed and elevated sites, and homeowners who plan to stay 20+ years.
Do double and triple glazing qualify for the SEAI grant?
Yes — both qualify. Both A-rated double and triple glazing meet the SEAI U-value threshold (≤1.4 W/m²K), so either spec is eligible for the SEAI windows and doors grant of up to €5,600 per home — windows are grant-aided by home type (up to €4,000 for a detached house) plus €800 per door. Your home must be built before 2011 and you must use an SEAI-registered installer. Airtight is registered; you apply directly to SEAI after a post-works BER. Full rules are on the official SEAI grant page.
Our honest recommendation: a mixed spec
On most homes, the best value is not triple everywhere — it is a mixed spec: A-rated double glazing in living rooms and south-facing windows, triple in north-facing bedrooms and bathrooms where heat loss is worst. That typically saves €1,000–€1,500 versus triple throughout, with under 5% measurable performance loss. Whether you choose casement, flush sash or sliding sash, every window we fit is A-rated as standard, with a triple upgrade available per opening.
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