PVC or Aluminium for nZEB Homes in 2026? Complete Guide by Energy Efficiency, Cost and Durability

What an nZEB house is and why the joinery choice matters

nZEB (Nearly Zero Energy Building) has been the mandatory standard for all new builds in Romania since 2021, under Government Decision 765/2016. An nZEB house has to reach a primary energy consumption of ≤ 100 kWh/m²/year.

Windows and doors make up 15-25% of the envelope surface and account for 25-40% of total heat losses. Choosing the wrong material — PVC or aluminium — can undo the entire energy balance of the house, even if the walls and roof are insulated perfectly.

Why does the PVC-versus-aluminium dilemma come up at all? Both materials have moved on considerably. Modern PVC is no longer "cheap plastic", and modern aluminium is no longer a "dangerous thermal conductor". The real difference lies in the use case.

Section 1 — The real differences between PVC and aluminium

Thermal insulation

PVC (Salamander bluEvolution 92):

• Profile thermal conductivity: λ = 0.17 W/(mK)
• Profile Uf = 0.95 W/(m²K)
• 6 chambers, 92 mm depth
• Total Uw with Saint-Gobain triple glazing + Warm Edge: 0.72 W/(m²K)

Aluminium (Alumil S77 Supreme):

• Pure profile conductivity: λ = 160 W/(mK) — brought down to about 0.3 W/(mK) by the 34 mm polyamide thermal break
• Profile Uf = 1.3 W/(m²K)
• Total Uw with triple glazing + Warm Edge: 1.0-1.2 W/(m²K)

Verdict on insulation: PVC wins clearly. A gap of 0.3-0.5 W/(m²K) in Uw means roughly 30% more heat lost through aluminium windows than through PVC ones at the same dimensions.

Structural strength and large glazed areas

Aluminium wins outright here, with structural strength three to four times that of PVC at the same section. The practical consequences:

• Large windows (over 1.5 m wide): aluminium allows visually slimmer profiles
• Large sliding units (3-6 m): aluminium is the standard solution
• Curtain walls: aluminium only
• Pivot windows: aluminium only

Design and appearance

Aluminium allows a much slimmer visible section — 30-45 mm against 60-80 mm for PVC — which means more glazed area, and any RAL colour including metallic or two-tone finishes. PVC offers the standard colour range and cannot be repainted after installation.

Service life and recyclability

Full comparison table: PVC vs aluminium for nZEB

Section 2 — What actually matters in nZEB windows

The calculation formula for the thermal coefficient of a complete window:

Uw = (Ag × Ug + Af × Uf + lg × Ψg) / (Ag + Af)

The critical elements, in order of impact:

• Triple glazing with argon — Ug = 0.5 against 1.0 for double glazing: the single largest factor
• Warm Edge spacer — Ψg = 0.03 W/(mK) against 0.1 for aluminium spacers
• Profile type — Uf differs between PVC (0.95) and aluminium (1.3)
• Low-E coating — reduces the solar factor g and the emissivity
• Installation — pre-compressed tapes and elimination of the thermal bridge account for 30-50% of the total performance

Section 3 — When PVC is worth it and when aluminium is

Apartment renovation: Salamander PVC bluEvolution 82 or 92 — Uw = 0.72, saving 20-30% against aluminium

Premium villa: a mix — PVC for bedrooms and bathrooms, aluminium sliders for the living area

Passive house (PHI): Salamander PVC bluEvolution 92 with Blaugelb precasings — the only option below Uw 0.8 W/(m²K)

Commercial space, offices, facades: Alumil aluminium (curtain wall system, S77, SF85)

Large sliding units (over 3 m): Alumil Smartia M19800 aluminium

Section 4 — Common mistakes when choosing

❌ Choosing on chamber count alone — a 5-chamber profile with triple glazing can outperform a 7-chamber one with double glazing

❌ Ignoring the installation — without pre-compressed tapes and without eliminating the thermal bridge at the sill, you lose 30-50% of the performance

❌ Triple glazing with a standard aluminium spacer — without Warm Edge, Uw rises by 0.1-0.15 W/(m²K)

❌ Profiles without EN certification — Salamander profiles carry IFT Rosenheim certification and a CE declaration to EN 14351-1

❌ Aluminium for passive houses — standard aluminium (Uf = 1.3 W/m²K) cannot reach Uw ≤ 0.8 W/(m²K)

FAQ — PVC vs aluminium for nZEB

Which is more energy efficient: PVC or aluminium?

PVC, through the Salamander bluEvolution 92 — Uw = 0.72 against 1.0-1.2 for aluminium. The difference comes from thermal conductivity: PVC λ = 0.17 W/(mK) against pure aluminium λ = 160 W/(mK).

Does modern aluminium still cause condensation?

With a 34 mm thermal break, a Warm Edge spacer and correct installation, there is no condensation down to an outside temperature of −15 °C.

What Uw do you need for nZEB?

Romanian regulations (Government Decision 765/2016): Uw ≤ 1.0 W/(m²K) for climate Zone II, which covers Bucharest and Ilfov. PHI passive houses: Uw ≤ 0.8 W/(m²K).

Is triple glazing worth it over double?

Yes, always for nZEB. Ug = 0.5 against 1.0 halves the losses through the glass. The price difference of 15-25% pays for itself in 5-8 years.

Which profiles are recommended for passive houses?

Salamander bluEvolution 92 with 52 mm Saint-Gobain SGG triple glazing, a Warm Edge spacer and Blaugelb Triotherm+ precasings. Uw = 0.66-0.72 W/(m²K).

Which lasts longer: PVC or aluminium?

Aluminium — 50+ years against 40+ for PVC. Both outlast any untreated timber alternative.

What should I choose for large glazed areas?

Aluminium, without exception. Its structural strength is three to four times higher and it allows sliding units up to 6 m wide.

Conclusion — a clear recommendation by scenario

The simple rule: maximum insulation → PVC. Design or large glazed areas → aluminium. Anything else → a mix.

Related: Complete nZEB System | nZEB Windows Guide Romania | Salamander Prices 2026

Neofort BIZ supplies Salamander (PVC) and Alumil (aluminium) in Bucharest and Ilfov. Request free consultation. Learn more about our Alumil systems we offer. For the full context, read the thermal break aluminium guide.