The temperature in cabe houses is always the same, about 20 degrees Celsius,
(What is the relationship between 'the same' and ' about 20 degrees Celsius'?)
3 answers
The phrase, "about 20 degrees Celsius" is an appositive describing "same."
Are they in apposition? Then 'same' is a pronoun or a noun?
Yes. They are in apposition. The "same" is used as a noun.