ASHRAE标准138建立了统一的实验室测试方法，用于评估室内空间中用于显热加热、显冷或两者的天花板的稳态热性能，目的是在可重复条件下对天花板进行评级。标准2021版的第138版包括更新的参考文献。

ASHRAE Standard 138 establishes uniform methods of laboratory testing for rating steady-state thermal performance of ceiling panels used in indoor spaces for sensible heating, sensible cooling, or both, with the objective of rating ceiling panels under repeatable conditions.The 2021 edition of Standard 138 includes updated references.