In Turkey, four degree-day regions stated in the standards are used in building heating energy load calculations. Deficiencies about the degree-day regions are mentioned in some other studies. In this paper, a different climatic zone approach suggested by International Energy Agency (IEA) regarding both heating and cooling degree-day data, derived from Typical Meteorological Year (TMY) data, is used. Results are presented graphically and compared with the current regulations. The second degree-day region, according to Turkish Standard (Thermal Insulation Requirements for Buildings (TS 825)), is divided into four climatic zones with the method proposed by IEA. Difference between monthly outdoor temperature values of the second degree-day region and cities in this region is up to 6.4 A degrees C which is high. The conclusion of this study is that the climatic variables should be evaluated in detail, and a new climatic zone study should be done regarding both heating and cooling loads. This will imply new building energy load calculations for all cities in Turkey.