Result
Preliminary calculation: This tool is for quick sizing and information. In real projects, load calculation, selection and commissioning require engineering calculations and a site survey. Results are approximate values.
Formulas
R_total = R_in + Σ (thickness / λ) + R_out, U = 1 / R_totalQ [W] = U × A × (T_in − T_out)Materials with low thermal conductivity (stone wool, EPS, XPS, PIR) provide insulation, while reinforced concrete and brick are poor insulators. Thermal bridges in the wall (columns, beams, balcony slabs) push actual losses above this calculation.
Notes
- The calculation is for steady-state conditions
- Air leakage (infiltration) is calculated separately
- Window and glass U values are entered separately
- Regulatory U limits vary by region
- Insulation directly affects the air conditioning load and the energy bill
Frequently asked questions
What does the U value show?
It shows the heat flow (W) through 1 m² of a building element per 1 K temperature difference; lower is better.
Where do I find the λ value?
From the product's technical data sheet or the relevant TS EN standards; the values in the tool are only approximate typical values.
How is the additional insulation for the target U value calculated?
The missing resistance is converted to a thickness assuming an insulation material with a conductivity of 0.035 W/mK (e.g., XPS).