Question 1

What does the multi-layer wall calculator compute?

Accepted Answer

This tool calculates the total thermal resistance R_total = 1/h_in + Σ(t_i/k_i) + 1/h_out, U-value (U = 1/R_total), heat flux q = (T_in − T_out)/R_total, and interface temperatures for each layer in real time. You can configure up to 5 layers with individual materials (concrete, insulation, steel, aluminum, glass, wood), thicknesses, and thermal conductivities, as well as interior and exterior convection coefficients.

Question 2

How do I use the multi-layer wall tool?

Accepted Answer

Select the number of layers (1–5) in the left panel and choose a material preset or manually set the thickness and thermal conductivity for each layer. Adjust the interior convection coefficient h_in, exterior convection coefficient h_out, indoor temperature T_in, and outdoor temperature T_out. The U-value, thermal resistance, heat flux, and heat loss per 10 m² update instantly. Use the temperature profile chart and resistance breakdown bar to identify design improvements.

Question 3

What is the U-value and why does it matter?

Accepted Answer

The U-value (overall heat transfer coefficient) represents the rate of heat flow through 1 m² of wall per 1 K of temperature difference, in units of W/m²K. It characterizes the overall thermal performance of the wall assembly: U = 1/(1/h_in + Σt_i/k_i + 1/h_out). Lower U-values indicate better insulation. Building energy codes in many countries define maximum allowable U-values for walls, roofs, and floors to meet energy efficiency targets.

Question 4

How does doubling insulation thickness affect the U-value?

Accepted Answer

Insulation thermal resistance R = t/k, so doubling the insulation thickness doubles its individual R-value. However, the total wall R_total includes convection resistances (1/h_in + 1/h_out) and other layer resistances, so the improvement to U = 1/R_total depends on what fraction of R_total the insulation represents. When insulation dominates the total resistance, doubling thickness yields a large U-value reduction. When convection resistances are significant, the benefit is more modest.

Multi-Layer Wall Thermal Resistance & U-Value Calculator