Hi Pat,
I believe it is referencing industry averages from the dataset. Pretty amazing that those tiles survived all those years though and in a pub nonetheless!
Are you trying to model an improved design or are you conducting a carbon footprinting study? I would say that if they’re already 100 years old, you could omit their embodied impacts in the study and only account for any repair/maintenance/replacement impacts (how likely will they survive another 100 years?).
