The effect of indoor heat gain from occupants as a bio-thermal source was hypothetically assessed in terms of its contribution to overall heating requirements during such occupancy and hence to potential energy savings. The spaces considered were classrooms in a sample of 6 public co-educational primary schools located within the city limits of Ankara built after 1998, the date when compulsory primary education was integrated to encompass grades 1 through 8 for ages 6 to 14, respectively. Being so, this allowed distinguishing disparities among age groups on the basis of classroom density and body surface area. Data for both were obtained from existing sources. As norms for the latter essentially pertained to adult populations, pertinent corrections were made for each of the age groups in question as well as for gender. Additional adjustments were made on the basis of the literature in order to integrate data on local weather conditions into heat balance equations. Energy requirements for heating were calculated according current Turkish standards. Results based on extensive comparisons using Student&amp / #8217 / s t-test confirmed that there were significant differences between grades in terms of supplementary heating requirements. These differences were not, however, large enough to warrant any meaningful intervention with regard to such design aspects as window orientation, exterior wall composition and/or indoor temperature level.