Convert between U-values, RSI, and R-values with our free thermal insulation calculator. Essential tool for architects, engineers, and energy auditors working with building envelope performance.
Understanding the Key Thermal Metrics
U-Value (W/m²·K):
Thermal Transmittance - Measures how much heat flows through a material
Lower values = better insulation
U=RSI1
RSI Value (m²·K/W)
Metric Thermal Resistance - Measures resistance to heat flow
Higher values = better insulation
RSI=U1
R-Value (ft²·°F·h/BTU)
Imperial Thermal Resistance
R=0.1761RSI
Calculator Features
- Bidirectional Conversion: Convert between U-value, RSI, and R-value
- Real-time Calculations: Automatic updates when any value changes
- Common Material Reference: Built-in comparison table
Example Calculation
Convert U-value 0.25 W/m²·K:
RSI=0.251=4.0m²⋅K/W
R=0.17614.0=22.7ft²⋅°F⋅h/BTU
FAQs
1. What is the difference between U-Value and RSI?
U-Value measures the rate of heat transfer through a material (W/m²·K), where lower values mean better insulation. RSI (R-Value in metric units) is the inverse of U-Value and represents thermal resistance. Higher RSI values indicate better insulation.
2. Why is converting between U-Value and RSI important?
Different regions and standards use different formats. U-Value is common in Europe, while RSI is used in Canada and some other metric-based regions. Converting helps compare insulation performance accurately when reviewing materials or complying with building codes.
3. Is a lower U-Value or a higher RSI better?
Yes. A lower U-Value or a higher RSI both indicate better insulation performance, meaning less heat loss and greater energy efficiency.
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