Building sector has a large share of the global energy consumption, and the energy requirements for space heating-cooling of a building has the highest share of all which is about 50% of total energy consumed in buildings. The meteorological air temperatures highly affect the annual (heating and cooling) energy consumption. The purpose of this study is on the basis of the temperatures, to determine the starting-ending days of heating-cooling seasons, the variation of these periods during years and the annual energy requirements. The degree-days concept was used to estimate the annual heating and cooling energy requirements. Considering the long-term outdoor air temperatures, the degree-days were calculated in addition to the lengths of seasons with the base temperatures from 14 to 18 C for heating period and from 20 to 24 C for cooling period. As expected, when the base temperature increases, the degree-days for heating season increase while they decrease for cooling season. Moreover, the yearly fluctuation in the energy requirement reaches 30% during the considered years. Generally, although there is a vague relationship, the cooling degree-days tend to be high when the heating degree-days are low.