Wall U-Value
Thermal transmittance of a layered building element. Layer resistances add in series with the inside and outside surface resistances.
Thermal transmittance U0.489W/m²K
- Total thermal resistance R_T
- 2.044 m²K/W
- Layer resistances R₁ / R₂ / R₃
- 0.023 / 0.422 / 1.429 m²K/W
- Heat loss Q = U·A·ΔT
- 98 W
- Loss per unit area
- 9.8 W/m²
METHOD
How it is calculated
R = t / λ (each layer) R_T = R_si + ΣR + R_se U = 1 / R_T Q = U · A · ΔT
ASSUMPTIONS & NOTES
- Defaults: 2 cm lime-cement plaster, 19 cm hollow clay brick, 5 cm EPS.
- For walls TS 825 / ISO 6946 use R_si = 0.13 and R_se = 0.04 m²K/W; the permitted U-value depends on the climate zone.
- Thermal bridges and condensation are not checked.
Results are for preliminary design and checking; base the final design on the governing standard and safety factors.
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