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Large windows mean light, space and freedom — but thermally they are a challenge. A window's R-value (0.5–1.0 m²·°C/W) is 3–5× lower than that of an insulated wall (3–5 m²·°C/W). Each square metre of glazing loses several times more heat than a wall.
Glazing unit | Formula | R, m²·°C/W | U, W/(m²·°C) | Price per m², ₽ (2026) |
|---|---|---|---|---|
Single-chamber standard | 4-16-4 | 0.32 | 3.1 | 1,800–2,500 |
Double-chamber standard | 4-10-4-10-4 | 0.47 | 2.1 | 2,500–3,500 |
Double + i-glass | 4-10-4-10-4i | 0.65 | 1.5 | 3,500–5,000 |
Double + i-glass + argon | 4-14Ar-4-14Ar-4i | 0.80–1.0 | 1.0–1.25 | 4,500–6,500 |
Triple + 2× i-glass + argon | 4i-12Ar-4-12Ar-4-12Ar-4i | 1.0–1.2 | 0.8–1.0 | 7,000–10,000 |
Low-E (i-glass) reflects IR back inside, cutting losses 30–40%. Argon has 34% lower conductivity than air. Minimum for the Leningrad Region — double-chamber with i-glass and argon.
PVC ≥70 mm (5+ chambers) or thermally broken aluminium (≥30 mm break) for large units. Cheap 58-mm profiles flex and freeze on big windows.
Reveals are skipped in 80% of houses. Insulate with 30–50 mm XPS, finish with mesh + plaster or drywall. Sill on XPS, never on foam — eliminates a thermal bridge. Mounting joint per GOST 30971-2012: outer PSUL tape + foam + inner vapour barrier tape.
In-floor convectors — 15,000–45,000 ₽, designed in at the screed stage
Free-standing convectors — 8,000–20,000 ₽
Warm skirting — 3,000–6,000 ₽/m
For −26 °C design temperature in the region — an in-floor convector under a panoramic window is a necessity.
Facade | Recommended glazing area | Reason |
|---|---|---|
South | Up to 40–50% of wall | Low winter sun delivers solar gain |
East / West | 20–30% | Morning/evening sun, summer overheating risk |
North | 10–15% | No direct sun, pure heat loss |
1 m² of southern glazing yields 100–200 W in winter; the same on the north loses 50–70 W.
Parameter | Standard | Energy-efficient |
|---|---|---|
Glazing | Double standard | Double + i-glass + argon |
Profile | PVC 60 mm, 3 chambers | PVC 80 mm, 6 chambers |
Reveals | No insulation | XPS 40 mm + plaster |
Convector | None | In-floor |
Window 1.5×2.0 m | 18,000–25,000 ₽ | 35,000–55,000 ₽ |
Heat loss (ΔT=40) | 250 W | 120 W |
Payback | — | 4–6 years |
Reveals left uninsulated — thermal bridge, mould
No PSUL and no vapour tape — foam fails in 3–5 years
No convector under floor-to-ceiling glass — condensation, fungus
Skimping on the profile — flex and freezing
Too much glazing on the north facade
StroyInvest24 designs and builds turnkey houses with panoramic glazing across the Leningrad Region.
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