A field study of students’ and teachers’ thermal comfort in a school building (St. Andrews Junior High School) was carried out at Madina, Accra. The building was chosen due to the sustainable design principles (e.g. form, orientation and ventilation) employed in the design and construction of the school. The aim of the study was to investigate peoples’ perception of comfort as well as examine the prevailing thermal conditions in the classrooms. Moreover, a comparative analysis of the results with the worldwide accepted ASHRAE recommendations was carried-out. The study employed the use of subjective assessments through questionnaires and physical measurements. The measured environmental parameters required the use of Hobo data sensors, these measured temperature and relative humidity values. The subjective responses concerned the occupants’ judgement about their thermal environment. One significant conclusion drawn was that the classroom spaces on the ground floor experienced lower temperatures, whilst those on the first floor had a higher temperature (difference of 2°C). The first floor classrooms experienced higher thermal conditions as a result of the absence of a ceiling. In addition, though a large majority of the respondents accepted their overall thermal conditions, a number of them still voted below the standard set by ASHRAE of 80% positive votes by occupants for thermal comfort. The study also showed that respondents in tropical countries such as Ghana may have a higher heat tolerance, since most of the interviewees accepted the existing thermal conditions which exceeded the standard of between 26°C and 28°C (summer comfort range) by 1°C to 5°C.