Window area & heat loss

Daylight norm: window area ≈ 1/5.5–1/8 of living room floor area (DBN). Glazing heat loss = U × area × ΔT. Single-chamber U~2.8, double ~1.1–1.4, energy-saving i-glass ~0.9–1.1. More glazing to the south — winter solar gain; to the north — only losses.