Deceuninck Windows: Real Reviews from a Professional Installer

Deceuninck: the Belgian manufacturer committed to sustainability

Deceuninck is a Belgian manufacturer founded in 1937 that operates in more than 90 countries and is listed on the Brussels stock exchange. In Spain it has been present since 1984 and has a manufacturing plant in Borox (Toledo) — a 24,000 m² facility opened with an investment of 11 million euros.

What sets Deceuninck apart from other brands is its genuine commitment to the circular economy: they have the largest PVC recycling plant in the Benelux (45,000 tonnes/year), were the first to obtain RecyClass certification for recycled PVC, and their EcoPowerCore technology integrates recycled PVC into the core of profiles without any loss of performance.

We have installed Deceuninck windows in residential and renovation projects. This article reflects our real experience: what works, what doesn't, and who we honestly recommend them for.

Deceuninck window systems 2026

Deceuninck organises its catalogue around the Elegant system as its main platform, with variants depending on the sash type and performance level. It also offers the Zendow#neo for Passivhaus and the iSlide#neo as a sliding system.

Deceuninck Elegant: 76 mm, versatile platform

The Elegant is Deceuninck's flagship system: 76 mm depth, 6 chambers with a central gasket and glazing up to 70 mm. The interesting feature is that it offers 6 different sash designs on the same platform (Infinity, Abstract, Origin, Grando, Authentica and ThermoFibra Infinity), allowing aesthetic adaptation without changing the technical system.

• Profile depth: 76 mm (also available in 84 and 115 mm)
• Chambers: 6 with central gasket
• Uf profile: 0.93 W/m²K (with steel); 0.88 W/m²K (with ThermoFibra + Forthex)
• Maximum glazing: 70 mm

The ThermoFibra version replaces the steel reinforcement with continuous fibreglass integrated into the sash, improving thermal insulation by 30% and reducing weight. It is Deceuninck's answer to Rehau's RAU-FIPRO, though with a different approach (only in the sash, not throughout the frame).

Deceuninck Zendow#neo Premium: Passivhaus at 70 mm

The Zendow#neo Premium has a notable achievement: it is the first 70 mm profile to be Passivhaus certified (temperate climate, phB level). It achieves a Uw of 0.98 W/m²K with only 70 mm depth thanks to the continuous fibreglass reinforcement (FVC) integrated into the profile.

• Depth: 70 mm (frame) / 82 mm (sash)
• Chambers: 5 (frame) / 6 (sash)
• Uw window: 0.98 W/m²K
• Triple glazing: up to 54 mm

Deceuninck iSlide#neo: minimalist sliding window

The iSlide#neo is Deceuninck's sliding system with a central section of just 35 mm — one of the narrowest on the market. With a 70 mm frame depth, it achieves a Uw of 1.2 W/m²K with double glazing and accepts sashes up to 2.5 m wide by 2.7 m high.

• Frame depth: 70 mm / sash 46 mm
• Visible central section: 35 mm
• Uf profile: 1.4 W/m²K

Exclusive Deceuninck technologies

ThermoFibra: Structural continuous fibreglass integrated into the sash during extrusion. Replaces steel in the sash, improving insulation by 30% and reducing weight and material by 40%. Nominated for the Fensterbau Frontale 2026 innovation award.

Forthex: Thermal reinforcement for the frame based on rigid recycled PVC foam reinforced with steel wire. Reduces CO₂ emissions by 84% compared to conventional steel. Combined with ThermoFibra in the sash, a window without solid steel is achieved.

EcoPowerCore: High-performance recycled PVC in the profile core through co-extrusion. Each kg of recycled PVC reduces CO₂ emissions by 2 kg. The outer profile is virgin to maintain surface quality; the inner core is 100% recycled.

Real advantages of Deceuninck windows

• Best value for money on the market — The Elegant 76 offers performance comparable to a Kömmerling 76 AD but at a price 10-15% lower. For projects with many windows, the accumulated saving is significant.
• Very versatile Elegant platform — A single system with 6 different sash designs allows aesthetic adaptation (minimalist, classic, flush) without changing the technical profile or fabricator.
• Manufactured in Spain (Borox, Toledo) — Competitive delivery times and local technical support. You are not dependent on imports from Central Europe.
• Zendow#neo for Passivhaus at 70 mm — If you need Passivhaus certification but have space constraints, it is a solution very few brands offer.
• Genuine sustainability commitment — This is not greenwashing: they have the largest PVC recycling plant in the Benelux, verifiable RecyClass and VinylPlus certifications, and concrete technologies (EcoPowerCore, Forthex) with measurable CO₂ reduction metrics.

Limitations and weak points

• Less well-known brand in Spain — Most private customers have never heard of Deceuninck. When you propose the brand, you have to explain who they are. With Kömmerling or Cortizo that doesn't happen.
• Limited high-end range — The Elegant reaches 0.88 W/m²K with ThermoFibra, but does not have an 86-88 mm system comparable to Rehau's GENEO or Kömmerling's 88 MD. For maximum-efficiency projects it may fall short.
• The Zendow#neo is hard to find — Although it technically exists, very few fabricators in Spain work with it regularly. In practice, the Elegant is what you will find.

Real opinions: our experience installing Deceuninck

We have installed Deceuninck in mid-range and upper mid-range residential projects. These are our honest assessments:

• "The Elegant is a straightforward profile" — It delivers what it promises with no surprises. Manufacturing tolerances are good, hardware fits well and the PVC surface finish is solid. Not spectacular, but reliable.
• "The price wins the argument when there are many windows" — On a project with 12 windows, a 10-15% difference versus Kömmerling meant a saving of over 800 € that the client could put towards better glazing. That is noticeable in the final result.
• "The iSlide#neo sliding window has an impressive profile" — The 35 mm central section is genuinely minimal. In a living room with a large opening onto a terrace, the visual effect is striking. Air tightness is class 4, better than many sliding windows on the market.
• "The weak point is the marketing, not the product" — Deceuninck does not invest in consumer-facing advertising the way Kömmerling does. Many customers come asking for Kömmerling and when you show them the Elegant's specs side by side, they are surprised.
• "For a coastal holiday home, it is our go-to recommendation" — The Elegant has good salt resistance, the price is reasonable for a holiday property project and the performance is more than sufficient for a Mediterranean climate.

Deceuninck vs other brands: head-to-head comparison

The most common comparison is Deceuninck Elegant vs Kömmerling 76 AD, as they compete in the same segment:

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Guide prices for Deceuninck windows 2026

Guide prices including installation in the Girona and Costa Brava area. VAT included:

• Deceuninck Elegant — Casement 100×120 cm, double glazing: from 350 €
• Deceuninck Elegant — Tilt & turn 120×120 cm, double glazing: from 430 €
• Deceuninck Elegant — Tilt & turn 120×120 cm, triple glazing: from 550 €
• Deceuninck Elegant — French door 90×210 cm, double glazing: from 500 €
• Deceuninck Elegant ThermoFibra — Tilt & turn 120×120 cm, triple glazing: from 650 €
• Deceuninck iSlide#neo — Sliding 200×210 cm, double glazing: from 900 €

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Who do we recommend Deceuninck windows for?

• Renovations with a tight but demanding budget — If you want first-tier European manufacturer quality without paying the Kömmerling premium, the Elegant offers the best price/performance balance on the market.
• Projects with many windows — In a home with 10-15 windows, a 10-15% saving per unit amounts to a total difference of 1,000-2,000 €. That money can go towards better glazing or better hardware.
• Coastal holiday homes — Good salt resistance, reasonable price and performance that is more than sufficient for a Mediterranean climate.
• Sliding windows with maximum glazing — The iSlide#neo with its 35 mm central section is hard to beat in PVC at that price point.

Conclusion: is Deceuninck worth it?

Deceuninck is the brand we recommend when budget matters but quality is non-negotiable. The Elegant is a solid, well-made profile with upper mid-range performance at mid-range prices. It doesn't have the name recognition of Kömmerling or the radical innovation of Rehau, but in day-to-day installation it performs without drama.

Its weak point is brand awareness: many customers have never heard of the brand. But as soon as they see the numbers next to the competition, the value for money speaks for itself. For us, Deceuninck is one of the brands that delivers the most satisfaction in mid-range residential projects.

Frequently asked questions about Deceuninck windows

Does Deceuninck manufacture in Spain?

Yes, Deceuninck has had a production plant in Borox (Toledo) since 2008, with 24,000 m² of facilities. The profiles installed in Spain are manufactured locally.

What is ThermoFibra?

ThermoFibra is Deceuninck's technology that integrates continuous fibreglass into the profile sash during extrusion, replacing the steel reinforcement. It improves thermal insulation by 30% and reduces weight by 40%. It has been nominated for the Fensterbau Frontale 2026 innovation award.

How much do Deceuninck windows cost?

The Elegant system with double glazing starts from around 350 € per installed window (100×120 cm). With triple glazing and ThermoFibra, a tilt & turn 120×120 cm is around 650 €. Prices for the Girona and Costa Brava area including installation.

Deceuninck or Kömmerling?

Kömmerling has more brand prestige and Full Cover technology in finishes. Deceuninck offers very similar performance at a price 10-15% lower. If budget is the deciding factor, Deceuninck. If you prefer the better-known brand, Kömmerling.

Are Deceuninck windows Passivhaus certified?

The Zendow#neo Premium system is certified as a Passivhaus component for temperate climates (phB level). It is the first 70 mm profile to achieve this. The Elegant does not have Passivhaus certification but comfortably meets the Spanish building regulations (CTE).

What warranty do Deceuninck windows carry?

Deceuninck offers a 3-year warranty against manufacturing defects, 10 years against profile discolouration and 5 years on hardware. The real durability of the profile is around 30 years.