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Insulation R-Value Calculator
Find the minimum R-value for walls and roofs as per ECBC 2017 (Energy Conservation Building Code, India) by climate zone
Civil
📋ECBC 2017 — Bureau of Energy Efficiency (BEE), Table 4.2 (Opaque Envelope Requirements)
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Estimation tool only. Results are indicative — not a substitute for professional engineering design or site-specific survey. Always verify with a qualified civil, structural, or MEP engineer before ordering materials or commencing construction.
Calculate
Results are estimates only. Verify with a qualified engineer before use.
Formula
R-value (m²·K/W) = thickness / thermal_conductivity U-value = 1 / R_total ECBC 2017 climate zone minimum R-values (overall assembly): Composite (Delhi, Jaipur) → Roof: 3.5 Wall: 1.5 Hot & Dry (Jodhpur, Ahmedabad) → Roof: 4.0 Wall: 1.5 Warm & Humid (Mumbai, Chennai) → Roof: 3.5 Wall: 1.5 Temperate (Pune, Hyderabad) → Roof: 3.0 Wall: 1.0 Cold (Shimla, Leh) → Roof: 5.0 Wall: 2.0
RThermal resistance (m²·K/W)
tInsulation thickness (m)
kThermal conductivity (W/m·K)
UOverall heat transfer coefficient (W/m²·K)
Reference Standard
ECBC 2017 — Bureau of Energy Efficiency (BEE), Table 4.2 (Opaque Envelope Requirements)
Practical Tips
- •PUF (polyurethane foam) has the best R-value per mm of thickness — ideal when space is constrained in retrofits.
- •In hot climates, reflective foil insulation (radiant barrier) under the roof dramatically reduces solar heat gain even at low R-values.
- •ECBC 2017 is mandatory for all new buildings above 100 kW connected load in India under the Energy Conservation Act 2001.