A constant, equal to a material’s k-value (Thermal Conductivity) divided by the material’s thickness in inches; used often for materials of composite construction such as insulation. For more information, click here.

time rate of heat transferred through a composite structure separating two temperature zones (for planar components: product of U-value and area) [W/K] (Wärme-) leitwert

The heat conduction power of a substance; substances with a very low thermal conductance are called insulators.

The time rate of heat flow through unit area of a body induced by unit temperature difference between the body surfaces. Units are Btu / (hour ft2 ¡F) [Imperial system] or Watts / (m2 ¡C) [SI system]. See "Thermal resistance".

The rate of heat flow, in BTU's per hour, through a square foot of material or a combination of materials whose surfaces have a temperature differential of 1 F.

The number of Btus per hour conducted through one square foot of a material or materials for a 1Â°F temperature difference between the faces. Units are measured by the following formula: Btu/hr-ft2Â°F or, in SI, W/m2 Â°C.

A specific unit of heat flow that is used to determine the specific thickness of material or for materials of combination construction, such as laminated insulation.

Time rate of heat flow through a body from one of its bounding surfaces to the other for a unit temperature difference between the two surfaces, under steady conditions (Btu/h*ft2* F) [W/9m2*K].

(1) A unit of heat flow that is used for specific thicknesses of material or for materials of combination or composite construction, such as laminated insulation. The formula for thermal conductance is: C = _________k__________ THICKNESS IN INCHES (2) Heat energy in Btu per hour (Btuh) transferred via conductance only through 1-ft2 are of homogeneous material per ?F temperature difference from surface to surface. The unit is Btuh/(ft.2?F) [in metric terms, W/(m2.K)]; (3) The thermal transmission in unit time through unit area of a particular body or assembly having defined surfaces, when unit average temperature difference is established between the surfaces: C=Btu/h_ft__?F;C=(W/m__K.