This lab applies Fourier’s law in steady, one-dimensional conduction through three homogeneous layers in series. In each slab, temperature varies linearly with thickness. Per unit area, layer resistance is R″ = L/k (L in metres, k in W/(m·K)). Total resistance adds: R″_tot = Σ R″_i, heat flux q″ = (T_left − T_right) / R″_tot, and U = 1/R″_tot. The drawing shows a color gradient by temperature, a T(x) polyline at interfaces, and an arrow for q″ from hot to cold. A one-click preset loads plaster / brick / mineral wool thicknesses and conductivities as a teaching example, not a certified U-value for a real building.
Who it's for: Introductory heat transfer and building-science intuition; complements the 2D heat-transfer playground.
Key terms
Fourier conduction
thermal resistance R″
U-value
series layers
heat flux q″
thermal conductivity k
How it works
Steady one-dimensional conduction through three layers in series: temperature is linear in each slab, and the heat flux q″ = (T_left − T_right) / Σ(L/k) per unit area. Compare thermal resistance of plaster, masonry, and insulation.
Frequently asked questions
Why is T a straight line inside each layer?
With no internal sources and steady 1D conduction in a uniform material, the heat equation reduces to d²T/dx² = 0, so T is linear in x. Different slopes appear in different layers because k and thickness change the thermal resistance.
Does this U-value match my wall certificate?
No. Real envelopes include surface resistances, air gaps, moisture, and 2D/3D bridges. The simulator isolates bulk conduction in three slabs with ideal interfaces.
What if T_right is hotter than T_left?
Then q″ is negative: heat flows from right to left. The arrow and displayed flux magnitude reflect that sign convention.