Our heat transfer coefficient converter allows precise conversion between different units of thermal conductance, including watts per square meter kelvin, kilocalories per hour per square meter celsius, and BTU per hour per square foot fahrenheit.
The heat transfer coefficient (also known as the film coefficient or convective heat transfer coefficient) is a quantitative characteristic of convective heat transfer between a fluid medium and the surface it flows over. It represents how effectively heat is transferred across an interface between materials or between a material and a fluid. In building science, it's often referred to as the U-value.
Convert between different heat transfer coefficient units with our free online calculator. Perfect for engineering, scientific, and professional applications.
Common heat transfer coefficient conversions
| From | To | Context |
|---|---|---|
| 5.678 Watts Per Square Meter Kelvin (W/m²·K) | 1.0000 Btu Per Hour Square Foot Fahrenheit (BTU/h·ft²·°F) | Standard U-value conversion factor |
| 0.25 Btu Per Hour Square Foot Fahrenheit (BTU/h·ft²·°F) | 1.4195 Watts Per Square Meter Kelvin (W/m²·K) | Well-insulated wall assembly |
| 10 Kilocalories Per Hour Square Meter Celsius (kcal/h·m²·°C) | 11.6300 Watts Per Square Meter Kelvin (W/m²·K) | Heat exchanger specification |
Heat transfer coefficients (U-values) are essential inputs for building energy models to predict heating and cooling loads.
Engineers use heat transfer coefficients to size heat exchangers and predict their performance under various conditions.
U-values are used to rate the thermal performance of windows and glazing systems in building codes and energy standards.
Heat transfer coefficients help engineers design equipment like boilers, condensers, and evaporators for optimal thermal performance.
U-value (heat transfer coefficient) measures how easily heat flows through a material or assembly, with lower values indicating better insulation. R-value measures thermal resistance, with higher values indicating better insulation. They are reciprocals of each other: U = 1/R.
Heat transfer coefficients can be determined experimentally using heat flux sensors and temperature measurements, calculated theoretically using heat transfer equations and material properties, or estimated using empirical correlations based on fluid properties and flow conditions.
Good U-values vary by climate and building component. In cold climates, walls typically aim for U-values below 0.25 W/m²·K (0.044 BTU/h·ft²·°F), while high-performance windows might target U-values around 1.1-1.4 W/m²·K (0.2-0.25 BTU/h·ft²·°F).
Lower heat transfer coefficients mean less heat flows through building components, resulting in lower heating and cooling energy consumption. Improving (lowering) U-values through better insulation and window technologies is a primary strategy for increasing building energy efficiency.
The SI unit of heat transfer coefficient. It represents the rate of heat energy transfer of one watt through an area of one square meter when there is a temperature difference of one kelvin.
A unit used in some engineering applications, especially in regions that traditionally use the calorie. One kcal/h·m²·°C equals approximately 1.163 W/m²·K.
A unit commonly used in HVAC and building engineering in the United States. One BTU/h·ft²·°F equals approximately 5.678 W/m²·K.
| Application/Material | Typical U-value (W/m²·K) | Equivalent (BTU/h·ft²·°F) |
|---|---|---|
| Single glazed window | 5.0 - 5.8 | 0.88 - 1.02 |
| Double glazed window | 2.8 - 3.0 | 0.49 - 0.53 |
| Triple glazed window | 0.8 - 1.4 | 0.14 - 0.25 |
| Typical insulated wall (modern) | 0.25 - 0.35 | 0.044 - 0.062 |
| Passive house standard wall | 0.10 - 0.15 | 0.018 - 0.026 |
| Uninsulated solid wall | 1.5 - 2.0 | 0.26 - 0.35 |
In building science, the heat transfer coefficient (U-value) is used to calculate heat loss through building components using the equation:
Where:
This equation is fundamental to building energy calculations, HVAC system sizing, and energy code compliance. Building codes typically specify maximum allowable U-values for different building components based on climate zone.