Triple glazing windows in Luxembourg 2026: prices, performance and subsidies
By Yacine Sahnoune, founder of renov.lu
Triple glazing achieves a thermal coefficient of Uw 0.6–0.9 W/m²K, versus 1.0–1.3 W/m²K for modern double glazing — delivering about 10–15% more heating savings (up to 30% versus single glazing). In Luxembourg, this performance is directly rewarded by the Klimabonus 2026 and Enoprimes grants, which can be combined with 3% VAT and municipal subsidies. For a standard window (1.23 × 1.48 m), the Klimabonus (€70/m² of window) comes to about €127 per window, or €146 if the approval in principle is requested by 30 June 2027 (€80/m²), excluding Enoprimes. Key condition: obtain the MyGuichet.lu prior approval before signing your order — this rule applies without exception.
- Performance: a triple-glazed window achieves Uw 0.6–0.9 W/m²K, versus 1.0–1.3 W/m²K for modern double glazing; only glazing with Ug ≤ 0.6 W/m²K, in practice triple glazing, qualifies for the Klimabonus.
- Price: in Luxembourg, an installed standard window (1.23 × 1.48 m) costs €750–950 with triple glazing, versus €500–650 with double glazing; replacing all the windows of a medium-sized home costs €20,000 to €40,000.
- Klimabonus: €70/m² of window, or €80/m² if the approval in principle is requested by 30 June 2027, i.e. about €127 (€146) per standard window; the approval in principle must be obtained before you sign the order.
- Conditions: the building must be over 10 years old (date of the building permit), and the adjacent wall, or the roof of a heated attic, must reach U ≤ 0.85 W/m²K; otherwise double-flow ventilation (MVHR) is required.
- Net cost: for 10 standard windows at €8,500 excl. VAT, 3% VAT (€255 instead of €1,445 at 17%) and a Klimabonus of about €1,274 (€1,456 at the increased rate) leave about €7,300–7,480 to pay, before Enoprimes.
- Payback: the triple-glazing premium pays back in 15 to 25 years in average conditions; it is only fully worthwhile when the walls themselves are highly insulated (Uwall ≤ 0.15–0.20 W/m²K).
Simulate your grants and request free quotes
Estimate your eligible subsidies in 2 minutes, then compare quotes from verified installers in Luxembourg.
Triple vs double glazing: full comparison
Both work on the same principle: trapping gas (argon or krypton) between glass panes to limit heat exchange. Triple glazing adds a third pane and a second gas cavity, creating a significantly superior thermal barrier. The trade-off: frames are 50% heavier (around 30 kg/m² vs 20 kg/m²), slightly thicker (36–44 mm vs 24–28 mm) and natural light transmission is marginally reduced (approximately 5–10%).
| Feature | Modern Low-E double glazing | Argon/krypton triple glazing |
|---|---|---|
| Thermal coefficient Uw | 1.0 – 1.3 W/m²K | 0.6 – 0.9 W/m²K |
| Total thickness | 24 – 28 mm | 36 – 44 mm |
| Acoustic insulation Rw | 30 – 34 dB (standard) 38 – 42 dB (acoustic specialist) | 32 – 36 dB Not better than acoustic double |
| Solar factor g | ≈ 0.60–0.65 (high gains) | ≈ 0.45–0.55 (reduced gains) |
| Light transmission Tl | ≈ 80% | ≈ 68–72% |
| Heating savings vs single glazing | up to 20% | up to 30% |
| Klimabonus eligibility (glazing Ug ≤ 0.6 W/m²K) | No | Yes, if Ug ≤ 0.6 |
| Klimabonus 2026 amount | — | €70/m² (€80/m² if approval in principle requested by 30/06/2027) |
| Standard window installed price (Luxembourg) | €500 – €650 | €750 – €950 |
| Indicative lifespan | 25 – 30 years | 25 – 35 years |
| Glazing weight | ≈ 20 kg/m² | ≈ 30 kg/m² (+50%) |
For passive houses and renovations targeting energy class A in Luxembourg, triple glazing is virtually essential. For a standard renovation of a 1970–1990 home, high-quality double glazing (Uw ≤ 1.0 W/m²K) may be technically sufficient, but it does not qualify for the Klimabonus, which requires glazing with Ug ≤ 0.6 W/m²K. Triple glazing qualifies for the Klimabonus and delivers superior long-term energy savings — particularly on north-facing façades where solar gains are absent.
Double or triple glazing: the 2026 figures to decide
In Luxembourg in 2026, triple glazing carries a premium of 250 to 300 € per window (750 – 950 € installed versus 500 – 650 € for low-E argon double glazing), while only triple glazing (Ug ≤ 0.6 W/m²K) qualifies for the Klimabonus: about €127 per standard window (€146 if the approval in principle is requested by 30 June 2027). The decision should therefore rest first on the physics of your home — triple glazing only pays off fully when the walls themselves are highly insulated (Uwall ≤ 0.15 – 0.20 W/m²K).
| Criterion | Low-E argon double glazing | Argon/krypton triple glazing |
|---|---|---|
| Ug (glazing only) | 1.0 – 1.1 W/m²K | 0.5 – 0.7 W/m²K |
| Uw (complete window) | 1.0 – 1.3 W/m²K | 0.6 – 0.9 W/m²K |
| Solar factor g | ≈ 0.60 – 0.65 | ≈ 0.45 – 0.55 (−25 % solar gains) |
| Acoustics Rw | 30 – 34 dB (38 – 44 dB with laminated acoustic double) | 32 – 36 dB — no better than acoustic double glazing |
| Weight | ≈ 20 kg/m² | ≈ 30 kg/m² (+50 %, reinforced frame required) |
| 2026 installed price | 500 – 650 €/window | 750 – 950 €/window (+45 to 50 %) |
A frequent special case: noise. Against a busy road or a railway line, standard triple glazing (Rw 32 – 36 dB) brings nothing — laminated asymmetric acoustic double glazing (e.g. 8/14/6 PVB, Rw 42 – 44 dB) is the answer. The most rational strategy is often mixed: low-E double glazing on south-facing façades to keep the free solar gains (1 m² of south glazing = 100 to 200 W of passive heating in winter), triple glazing on north façades and in the Ardennes municipalities where lows drop below −15 °C. Payback on the triple-glazing premium: 15 to 25 years in average conditions. Walls, doors and ceiling: more solutions in our guide to bedroom sound insulation.
The Uw coefficient: how to read it and why it matters
The Uw coefficient (W/m²K) measures total heat loss through the complete window — glazing and frame — per square metre per degree. The lower the value, the better the insulation. The Klimabonus 2026, however, sets its condition on Ug (the glazing-only coefficient): Ug ≤ 0.6 W/m²K. It no longer distinguishes performance levels: it pays a single flat rate per m² of window (external dimensions). The examples in this guide use a standard 1.23 m × 1.48 m window.
| Criterion | Klimabonus 2026 requirement | In practice | Grant |
|---|---|---|---|
| Glazing | Ug ≤ 0.6 W/m²K | Triple glazing | €70/m² of window |
| Anti-condensation | Wall (or heated-attic roof) U ≤ 0.85 W/m²K, or MVHR | Insulated wall or MVHR | Access condition |
| Temporary increase | Approval in principle requested by 30/06/2027 | — | €80/m² of window |
The Uw coefficient covers both glazing (Ug) and frame (Uf). A triple-glazed unit may show an excellent Ug (0.5 W/m²K) but if the frame is poor quality (Uf = 1.8 W/m²K), the overall Uw of the assembled window can remain at 1.1 W/m²K — a poor performance, even if the glazing meets the Klimabonus condition (Ug ≤ 0.6 W/m²K). Always demand both the Ug of the glazing (Klimabonus condition) and the Uw of the complete installed window, certified by a product technical datasheet.
The Klimabonus for windows is also conditional on the thermal performance of the adjacent wall: the exterior wall (or the roof of a heated attic) must achieve U ≤ 0.85 W/m²K — or the home must have double-flow mechanical ventilation.
When to choose triple glazing in Luxembourg?
Triple glazing is not always the best choice. Its value varies significantly depending on project type, building orientation, and the overall state of the thermal envelope.
New build or full renovation targeting class A or passive standard
Triple glazing is practically mandatory to achieve Passivhaus standards or energy class A in Luxembourg. A new home must meet the NZEB standard (nearly zero-energy building), defined against a reference building: this is not the passive standard, but in practice it requires highly insulating windows. If your project aims to improve your energy rating to class A or B, triple glazing fits this logic.
North or north-east facing façades
North-facing façades receive no passive solar gain in winter. Triple glazing’s 30–40% improvement in Uw over double glazing is fully valorised there. For south façades, the calculation is more nuanced — see the double vs triple glazing comparison above.
Home already well insulated (walls, roof, ground floor)
Triple glazing’s benefit is maximised when the overall thermal envelope is already performant. If your home already has external wall insulation or roof insulation, triple glazing becomes highly relevant to complete the envelope.
Colder communes in the Luxembourg Ardennes
In the Ardennes region (Clervaux, Wiltz, Vianden, Troisvierges, Weiswampach…), winter temperatures are notably lower. The higher heating degree-days significantly improve the return on investment for triple glazing, shortening its payback period versus the national average.
Maximising Klimabonus grants
Only glazing with Ug ≤ 0.6 W/m²K — in practice triple glazing — qualifies for the Klimabonus: €70/m² of window (€80/m² if the approval in principle is requested by 30 June 2027), i.e. about €127 (€146) for a standard window — the economic case must rest primarily on long-term energy savings.
In an older home where walls and roof are not insulated, triple glazing alone will have limited impact. The Klimabonus for windows also requires an insulated exterior wall (U ≤ 0.85 W/m²K) or MVHR. If in doubt, see which works to prioritise in an energy renovation, follow our Klimabonus application steps, or consult a Klima-Agence accredited energy advisor.
PVC, aluminium or wood: which frame with triple glazing?
The frame material directly affects the overall Uw, durability, maintenance and cost. In all cases, installation is handled by a professional window fitter — always compare at least three quotes.
| Material | Typical frame Uf | Durability | Maintenance | Relative cost | Klimabonus eligible |
|---|---|---|---|---|---|
| Multi-chamber PVC | 1.0 – 1.4 W/m²K | 25 – 30 years | Very low | Reference | Yes |
| Thermally broken aluminium | 1.4 – 2.0 W/m²K | 40 – 50 years | Very low | +20 to +30% | Yes (if glazing Ug ≤ 0.6) |
| Wood | 1.1 – 1.5 W/m²K | 30 – 40 years (if maintained) | Moderate (painting/staining) | +15 to +25% | Yes |
| Composite wood-aluminium | 1.0 – 1.3 W/m²K | 35 – 45 years | Low (ext. alu) | +25 to +40% | Yes |
For aluminium frames, the quality of the thermal break is critical. Insist on a thermal break of at least 24 mm to achieve a competitive overall Uw with triple glazing. A low-quality aluminium frame (12–14 mm thermal break, Uf = 1.8 W/m²K) combined with an excellent triple-glazed unit can result in a final Uw of 1.1 W/m²K — a poor performance, even if the glazing meets the Klimabonus condition (Ug ≤ 0.6 W/m²K). Always verify the thermal break width on the manufacturer’s technical datasheet.
Insulated entrance door: the logical companion to a window replacement
In Luxembourg in 2026, an ageing entrance door can account for up to 12 % of a home’s heat losses: pre-1990 models routinely exceed Ud 2.5 W/m²K, more than double today’s requirements. The target threshold is Ud ≤ 1.1 W/m²K (EN 14351-1 certified), with the best doors reaching 0.8. Budget: 1,500 to 4,500 € installed, but the Klimabonus does not cover a solid entrance door: the law only covers windows and French windows.
| Material | Typical Ud | Lifespan | Installed price (Luxembourg) |
|---|---|---|---|
| Multi-chamber PVC | 0.9 – 1.2 W/m²K | 20 – 30 years | 1,500 – 2,800 € |
| Thermally broken aluminium | 0.9 – 1.1 W/m²K | 40 – 50 years | 2,200 – 4,500 € |
| Solid wood / wood-aluminium | 0.8 – 1.1 W/m²K | 30 – 50 years | 2,000 – 5,000 € |
| Composite / SMC | 0.8 – 1.0 W/m²K | 30 – 40 years | 1,800 – 3,500 € |
Three rules to keep the benefit: replace the complete unit (a 1970s-1990s steel frame without thermal break cancels the gain of a new leaf alone), meet the adjacent-wall condition for glazed doors (wall U ≤ 0.85 W/m²K or mechanical ventilation), and obtain the approval in principle before works (simplified single-measure procedure, DEPA-2026 form + DESC sheet). Full conditions in our Klimabonus grants guide and our energy renovation steps in Luxembourg.
Windows and door in a single project: request 3 free quotes.
Triple glazing window prices in Luxembourg in 2026
Prices include supply and professional installation in Luxembourg. For a full analysis of window costs, see our guide on window prices in Luxembourg.
| Window type | Double glazing (reference) | Triple glazing | Triple premium |
|---|---|---|---|
| Standard window (1.23 × 1.48 m) | €500 – €650 | €750 – €950 | +45 to +50% |
| French door | €800 – €1,300 | €1,200 – €1,800 | +40 to +50% |
| Bay window | €1,900 – €2,500 | €2,400 – €3,300 | +25 to +35% |
| Roof window (Velux type) | €600 – €900 | €900 – €1,300 | +45 to +50% |
For a medium-sized Luxembourg home (130–160 m²), the total budget for replacing all windows with triple glazing typically ranges between €20,000 and €40,000. Always request at least three comparative quotes from different certified installers — price differences can exceed 40% for identical work.
2026 grants: Klimabonus + Enoprimes + municipal aid
Window replacement is eligible for several stackable grants in Luxembourg. For a full overview, see our page on Klimabonus 2026 grants.
Klimabonus 2026 — simplified route vs full route
- Simplified route (single element): windows only, without a full energy audit; the company must be approved (law of 21 April 1993), otherwise an approved energy advisor follows the works on an ad hoc basis. Prior approval via MyGuichet.lu mandatory before works.
- Full route (with energy audit): windows as part of a broader project. Delivers the highest rates. See our guide on energy renovation steps in Luxembourg.
| Window type (standard size) | Klimabonus 2026 basic rate €70/m² |
Increased Klimabonus €80/m² (approval in principle requested by 30/06/2027) |
Conditions |
|---|---|---|---|
| Standard window (1.23 × 1.48 m) | ≈ €127 | ≈ €146 | Ug ≤ 0.6 W/m²K; wall U ≤ 0.85 W/m²K or MVHR |
| French door | ≈ €211 | ≈ €242 | same |
| Bay window | ≈ €405 | ≈ €465 | same |
Source: Guichet.lu and Enoprimes.lu — Klimabonus 2026 (€70/m², €80/m² increased rate) for standard sizes, excluding Enoprimes. Indicative amounts; verify exact figures via the Klima-Agence simulator.
Enoprimes must be requested before signing the order form — without exception. If this step is missed, the grant is permanently lost.
3% VAT
Reduced 3% VAT applies to renovation works on a Luxembourg primary residence at least 10 years old, capped at €50,000 of recoverable VAT. On a €15,000 window replacement, this saves €2,100 compared to the standard 17% rate.
Municipal grants
Almost all Luxembourg communes top up the Klimabonus: for 20 m² of windows, 82 of the 100 communes add €160 to €1,000 (amount for each commune in the table of municipal grants). You usually apply after the state decision, but check with your municipal administration before the works start: some regulations set conditions at that stage.
Net cost = Works price (excl. VAT) + 3% VAT − Klimabonus − Enoprimes − Municipal grantsExample for 10 standard triple-glazed windows (Ug ≤ 0.6):
Price excl. VAT: €8,500 | 3% VAT: €255 (instead of €1,445 at 17%) | Klimabonus: ≈ €1,274 (10 × 1.82 m² × €70), or ≈ €1,456 at €80/m²
→ Estimated net cost: ≈ €7,300–7,480 (before Enoprimes and any municipal grants)
Calculate your exact triple glazing grants
Our simulator integrates the 2026 Klimabonus, Enoprimes and municipal grants for your Luxembourg window project.
Klimabonus technical conditions for windows
To be eligible for the Klimabonus 2026, installed windows must meet technical conditions defined by Guichet.lu.
Building over 10 years old
The Klimabonus applies to residential buildings whose building permit was issued more than 10 years ago. The relevant date is that of the building permit issuance.
Glazing Ug ≤ 0.6 W/m²K
The entry condition for the Klimabonus on windows (in practice triple glazing); the grant is then a flat rate of €70/m² of window (€80/m² if the approval in principle is requested by 30 June 2027). Also check the Uw of the complete installed window (frame + glazing + spacer), which measures its actual performance.
Adjacent wall or double-flow VMC condition
Window replacement must be combined with an insulated exterior wall (or heated-attic roof) with U ≤ 0.85 W/m²K, or a double-flow VMC system.
One Klimabonus per element per property
The Klimabonus can only be granted once per construction element for a given property. Previous grants under RGD 2022 or PRIMe House preclude a new Klimabonus for the same element.
Specific case: roof windows (heated attic)
If the attic is heated, roof renovation must include replacement of roof windows over 10 years old with Uw > 1.4 W/m²K. The new roof window must achieve Uw ≤ 1.4 W/m²K.
Accredited installer and technically compliant invoice
The invoice must state the certified Uw of each installed window, dimensions, glazed area, brand and frame material. An incomplete invoice leads to automatic rejection of the Klimabonus application.
How to apply for triple glazing grants: step-by-step
The chronological order of steps is imperative. For the complete overview, see our guide on energy renovation steps in Luxembourg.
Enoprimes request — before signing the order form
The most critical step. Enoprimes must be requested before signing the order form. If this step is missed, the grant is permanently and irrevocably lost.
Klimabonus prior approval via MyGuichet.lu — before works
Before starting works, obtain prior approval via MyGuichet.lu using form DEPA-2026. Without this, no Klimabonus will be paid regardless of execution quality.
Check for municipal authorisation
Depending on window type, colour or property characteristics (listed building, protected zone), a municipal permit may be required before works begin.
Works carried out by the certified installer
The invoice must state the certified Uw of each window, dimensions, brand, frame material and glazing type. Keep all technical documents.
Submit the Klimabonus payment request
After receiving the final invoice, file the liquidation request on MyGuichet.lu. You have up to 4 years after 31 December of the invoice year to submit.
Check for municipal grants
Check with your municipality for additional energy renovation grants. Some regulations set conditions before the works start; you usually apply after the Klimabonus decision.
Simplify your admin: our verified partner installers in Luxembourg handle Klimabonus and Enoprimes formalities on your behalf.
Find a verified installer →Common mistakes to avoid when replacing windows in Luxembourg
Signing the order form before requesting Enoprimes. This mistake is irreversible: once the order form is signed, the Enoprimes application is automatically and definitively rejected.
Starting works without Klimabonus prior approval. The MyGuichet.lu prior approval is mandatory before any work begins. If works start without it, the Klimabonus grant is refused without exception or recourse.
Choosing triple glazing without checking the complete assembled window Uw. Always require both the glazing Ug (Klimabonus condition: ≤ 0.6 W/m²K) and the Uw of the complete installed window, certified by a manufacturer datasheet.
Installing triple glazing without checking the adjacent wall condition. If walls do not meet Uwall ≤ 0.85 W/m²K and you have no double-flow VMC, the Klimabonus for windows will not be accessible.
Ask your quotes to price both variants: compare 3 window quotes from companies established in Luxembourg — free and without obligation.
Frequently asked questions about triple glazing in Luxembourg
In practice, yes. The Klimabonus 2026 requires glazing with Ug ≤ 0.6 W/m²K, which in practice only triple glazing achieves: double glazing, even high-end Low-E argon (Ug 1.0–1.1), does not qualify. The grant is a flat rate of €70/m² of window (€80/m² if the approval in principle is requested by 30 June 2027). The double vs triple glazing comparison above details the differences.
Yes. It is not necessary to replace all windows. The Klimabonus can be obtained for a partial replacement. However, the grant can only be awarded once per construction element for a given property.
Yes, but the impact depends on the overall thermal envelope. Triple glazing delivers up to 30% heating savings versus single glazing, and approximately 10–15% more than modern well-insulated double glazing. In a medium-sized Luxembourg home, these savings typically represent €200–500 per year. Return on investment is typically 15 to 25 years under average Luxembourg conditions.
Yes. The Klimaprêt is a bank loan from state-approved Luxembourg banks (including BCEE) on which the State covers 1.5% interest per year (on up to €100,000 over up to 15 years); it is not a zero-rate loan. There is no incompatibility between the Klimabonus and the Klimaprêt: both can be used together for the same project.
Not necessarily. For windows-only replacement (single thermal envelope element), you can use the simplified Klimabonus route, which does not require a full energy audit. If you plan to renovate several elements simultaneously, the full energy advisory report is mandatory and unlocks the highest subsidy rates.
Slightly — around 5 to 10% less than equivalent Low-E double glazing. In practice, this is barely noticeable with modern high-transmission glazing. For light-sensitive rooms (large south-facing bays, verandas), choose a triple-glazed unit with Tl ≥ 70%.
Take action — simulate your grants and get quotes
Calculate your exact Klimabonus and Enoprimes subsidies for triple glazing in 2 minutes, then receive quotes from verified installers in Luxembourg.