gleiche DIN Wärmeübergangskoeffizient heat transmission coefficient. But I am not sure whether this is correct.
In transport of refrigerated food (ATP-Agreement), Wärmeübergangszahl is heat transfer coefficent, also referred to as Wärmeleitwert. In the standard covering thermal insulation of doors and curtains walls and facades, Wärmedurchgang is thermal transmission the so-called u-value. There is also a k-value but this is a penetration value. I have never been able to figure at the difference between these two values. But may be the explanation is somewhat helpful.

thermal transmittance coefficient is possible as well