Just a typo... The Architects Center purpose is to reduce building cost with 2% for each level. 2% was missing from description. Anyway, considering 100% the full amount of materials you need to build or upgrade something, the materials required were reduced at 88% from 100%. Hope that makes more sense now.

Yeh that makes sense, i gathered as much. I upgraded it again just to make sure, one thing i noticed though is that it reduced the cost of buildings except the resource producers, they all seem to cost the same BC as before