How Can I Improve Window Thermal Insulation in Bucharest? Complete Guide 2026
Technical Guide
May 3 2026·11 min read··Mihai DănălacheMihai Dănălache

How Can I Improve Window Thermal Insulation in Bucharest? Complete Guide 2026

Feeling heat loss through your windows in Bucharest? Complete guide 2026: how to improve thermal insulation of existing windows without replacement, when complete replacement is more cost-effective and what difference triple glazing makes.

Why Windows Are the Main Source of Heat Loss in Bucharest Homes

The cross-section image above shows a modern window profile with double thermal insulating glazing. The metal spacer between the two glass panes and the visible gap between profile and masonry are exactly where the greatest heat losses occur — and these losses are recoverable without necessarily replacing all the joinery.

Energy efficiency studies on Bucharest's housing stock show windows account for 25-40% of heat losses in a typical apartment. Heating bills in the 2024-2025 cold season rose 30-45% vs 2022 — making a window insulation investment more worthwhile than ever.

Diagnosis: How to Know Your Windows Are Losing Heat

Condensation on the interior glass surface — the clearest sign. If it appears on the central zone (not the edge), Ug is high (old double glazing with Ug = 1.1-1.6). If it appears at the glass edge, the problem is the spacer (solution: replace with Warm Edge spacer).

Cold draught near the window — poor gasket sealing or defective installation. Possible solution without full replacement: hardware adjustment + gasket replacement.

Cold frame to the touch — thermal bridge at installation. If the frame is significantly colder than the wall, the problem is the installation, not the profile.

Option 1 — Improvement Without Replacement (low cost, limited effect)

a) EPDM gasket replacement: Sealing gaskets degrade in 8-12 years. Replacement costs €6-16 per window and reduces air infiltration by 60-70%.

b) Hardware adjustment: Incorrectly adjusted Roto/Winkhaus hardware leaves the sash not pressing uniformly on the gasket. 3-axis adjustment costs €10-20 per window.

c) Applying Low-E film to existing glazing: Self-adhesive low-emissivity films (e.g. 3M Thinsulate) applied to the inner surface reduce Ug by 0.2-0.4 W/(m²K). Cost: €16-30/m². Disadvantage: does not resolve marginal condensation.

d) Exterior perimeter siliconing: If exterior silicone is cracked or missing, reseal with UV-resistant neutral silicone: €8-16 per window.

Option 2 — Glazing Pack Replacement (medium cost, significant effect)

If the profile is in good condition but the glazing is old double (Ug = 1.0-1.6), replacing only the glass pack offers the best cost/benefit ratio:

  • Old double → triple glazing with argon and Low-E: Ug drops from 1.0 to 0.5 W/(m²K) — 50% reduction
  • Cost of glass pack replacement: €30-60/m² (vs €80-140/m² for the complete window)
  • Condition: profile must be at least 70 mm deep to accept the 44 mm triple pack

Option 3 — Complete Window Replacement (high cost, maximum effect)

When the profile is more than 20 years old, deformed, or you want to reach nZEB standard (Uw ≤ 1.0 W/(m²K)):

Current situationCurrent UwAfter replacementAnnual saving*
Single glazing, timber frame4.5–5.0 W/(m²K)0.72 W/(m²K)€140–180/year
Old double glazing (1990-2005)2.2–2.8 W/(m²K)0.72 W/(m²K)€70–100/year
Modern double glazing (2010-2020)1.1–1.4 W/(m²K)0.72 W/(m²K)€24–40/year

*Estimate for 70 m² apartment, 8 standard windows, 2026 energy prices.

Which Profile to Choose for Bucharest

  • Salamander bluEvolution 82 (6 chambers, 82 mm) — optimal quality/price ratio for residential renovations in Bucharest. Uw = 0.8-0.95 W/(m²K) with triple glazing.
  • Salamander bluEvolution 92 (6 chambers, 92 mm) — for new builds or nZEB projects. Uw = 0.66-0.80 W/(m²K) with Saint-Gobain triple glazing and Warm Edge.

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Neofort BIZ — window thermal insulation specialist in Bucharest and Ilfov. Request free consultation.

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