Question:
WE could have a room temperature in a building, in winter that is not heated where the piping system is located, and the temperature could be 50 F whereas outside it could be -20 F, In this case what would be the ambient temperature?
Answer:
In this case it will be fair to say that ambient temperature is 50 F i.e. temperature of the surrounding environment where the system is located. This will be used in defining the thermal flux of outside of pipe wall.
See Also
"Thermal Transient Analysis" (TTA) - AutoPIPE Load Case