thermal conductance

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A measure of the ability of an object to allow the flow of heat from its warmer surface through the object to its colder surface, determined as the heat energy transferred per unit of time divided by the temperature difference between the two surfaces, expressed in watts per kelvin. The conductance of an object equals the conductivity of its material times its surface area (cross-section) divided by the distance between the two surfaces (thickness).
• noun The reciprocal of thermal resistance, usually measured in units of watts per kelvin.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics The thermal transmission in unit time though unit area of a particular body or assembly having defined surfaces, when unit average temperature difference is established between the surfaces.