Calculator
How it works
La resistenza termica di uno strato piano omogeneo è R = d/λ, dove d è lo spessore in metri e λ è la conducibilità termica in W/(m·K). La resistenza totale della parete è la somma delle resistenze dei singoli strati. Per ottenere la trasmittanza U è necessario aggiungere le resistenze superficiali Rsi e Rse (kernel trasmittanza_parete_semplificata).
Assumptions and conditions
This calculation is valid under the following conditions:
- Solo strati omogenei
- Regime stazionario
This calculation is valid when: Solo strati omogenei; Regime stazionario.
This is an informational calculation (unit conversion or physical definition). The margin of error is negligible if inputs are correct.
All inputs and outputs use SI units. Convert any values in other unit systems before entering them.
Limitations
This calculation does not apply in the following cases:
- Non include resistenze superficiali (Rsi, Rse) — per trasmittanza usare il kernel trasmittanza_parete_semplificata
Non include resistenze superficiali (Rsi, Rse) — per trasmittanza usare il kernel trasmittanza_parete_semplificata
Referenced standards
- UNI EN ISO 6946:2018
Formula source: UNI EN ISO 6946:2018. R_strato = d/λ.
Application examples
Laterizio porizzato 30 cm (λ=0.28)
Parete in blocchi di laterizio porizzato, senza isolamento aggiuntivo
Muratura 25 cm + cappotto EPS 10 cm
Soluzione con cappotto esterno in EPS da 10 cm su muratura esistente
Frequently asked questions
What does the Thermal Resistance of Layers calculator compute?
Calculate total thermal resistance of multiple material layers in series: R_total = Σ (d_i / λ_i) + surface resistances. For wall, roof, and floor assemblies.
When is this calculation valid?
This calculation is valid under the following conditions: Solo strati omogenei; Regime stazionario.
When is this calculator not appropriate?
Non include resistenze superficiali (Rsi, Rse) — per trasmittanza usare il kernel trasmittanza_parete_semplificata
How accurate is the result?
This calculator implements the standard form of the formula. Accuracy depends on the quality of the inputs provided. Source: UNI EN ISO 6946:2018. R_strato = d/λ..
What is the source of the formula?
UNI EN ISO 6946:2018. R_strato = d/λ. Referenced standards: UNI EN ISO 6946:2018.
Which parameter has the greatest influence on the result?
"Spessore strato 1 (m)" is the most influential parameter: a 10% change in this input produces approximately 10% change in "Resistenza strato 1 (m²·K/W)".
How does the result change under different conditions?
Comparison between "Reference conditions" and "Laterizio porizzato 30 cm (λ=0.28)": Resistenza strato 1 (m²·K/W) [m²·K/W]: increases by 285.7% (from 0.278 to 1.071). Resistenza strato 2 (m²·K/W) [m²·K/W]: decreases by 100.0% (from 2.000 to 0.000). Resistenza strato 3 (m²·K/W) [m²·K/W]: decreases by 100.0% (from 0.017 to 0.000). Resistenza totale (m²·K/W) [m²·K/W]: decreases by 53.3% (from 2.294 to 1.071).
Technical note
Per confronto: la resistenza termica totale senza strati superficiali viene usata in calcoli intermedi. Per la trasmittanza U completa, aggiungere Rsi=0.13 e Rse=0.04 m²K/W (parete verticale) secondo UNI EN ISO 6946.
Technical note
Un buon isolamento termico ha R elevata: pannello EPS 10 cm (λ=0.04) → R = 2.5 m²K/W; muratura in laterizio 30 cm (λ=0.3) → R = 1 m²K/W.
Technical deep dive
About this calculator
Calculate total thermal resistance of multiple material layers in series: R_total = Σ (d_i / λ_i) + surface resistances. For wall, roof, and floor assemblies.
Formula
R_i = d_i / λ_i | R_tot = Σ R_i
Validity conditions
This calculation is valid under the following conditions:
- Solo strati omogenei
- Regime stazionario
Result sensitivity
The result varies significantly with changes in the following parameters:
- Spessore strato 1 (m) [m]: linear sensitivity on "Resistenza strato 1 (m²·K/W)" (proportional, elasticity 1.00).
- Spessore strato 2 (m) [m]: linear sensitivity on "Resistenza strato 2 (m²·K/W)" (proportional, elasticity 1.00).
- Spessore strato 3 (m) [m]: linear sensitivity on "Resistenza strato 3 (m²·K/W)" (proportional, elasticity 1.00).
When this calculator does not apply
- Non include resistenze superficiali (Rsi, Rse) — per trasmittanza usare il kernel trasmittanza_parete_semplificata
Technical notes
- Per confronto: la resistenza termica totale senza strati superficiali viene usata in calcoli intermedi. Per la trasmittanza U completa, aggiungere Rsi=0.13 e Rse=0.04 m²K/W (parete verticale) secondo UNI EN ISO 6946.
- Un buon isolamento termico ha R elevata: pannello EPS 10 cm (λ=0.04) → R = 2.5 m²K/W; muratura in laterizio 30 cm (λ=0.3) → R = 1 m²K/W.
Technical analysis
Method: Calculate total thermal resistance of multiple material layers in series: R_total = Σ (d_i / λ_i) + surface resistances. For wall, roof, and floor assemblies.
Reference result: Resistenza strato 1 (m²·K/W): 0.278 m²·K/W, Resistenza strato 2 (m²·K/W): 2.000 m²·K/W.
Sensitivity analysis
Elasticity: percentage change in output relative to percentage change in input (1.0 = linear).
| Input | Primary output | Elasticity | Relationship |
|---|---|---|---|
| Spessore strato 1 (m) [m] | Resistenza strato 1 (m²·K/W) | 1.00 | linear |
| Spessore strato 2 (m) [m] | Resistenza strato 2 (m²·K/W) | 1.00 | linear |
| Spessore strato 3 (m) [m] | Resistenza strato 3 (m²·K/W) | 1.00 | linear |
| λ strato 1 [W/(m·K)] [W/(m·K)] | Resistenza strato 1 (m²·K/W) | -0.91 | linear |
| λ strato 2 [W/(m·K)] [W/(m·K)] | Resistenza strato 2 (m²·K/W) | -0.91 | linear |
| λ strato 3 [W/(m·K)] [W/(m·K)] | Resistenza strato 3 (m²·K/W) | -0.91 | linear |
Note: The result is particularly sensitive to "Spessore strato 1 (m)" [m]: a 10% change produces approximately 10% change in "Resistenza strato 1 (m²·K/W)".
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