The purpose of this study is to evaluate whether the air conditioning units (AAC) currently used in an educational institution are suitable to promote thermal comfort for classroom users, as well as to resize the thermal load based on the norms of the ABNT 5858:1983 and 16401-1:2008. It was found that no classroom has an appropriate AAC for the calculated thermal load. In 7 rooms, the calculated thermal load was higher by NBR 16401-1:2008. As the average thermal load calculated for the rooms is approximately 32,523 BTU, we suggest the use of 30,000 BTU AACs (energy rating A).