Seasonal energy requirements and fuel consumption for heating purposes in the buildings in a city can be estimated from the predetermined architectural design and material characteristics of the buildings, the regular meteorological temperature measurements and the population of the city. This paper considers the city centers of Istanbul, Ankara, Bursa, Adana and Konya in Turkey and presents a detailed account of the practical seasonal heating energy requirements in an apartment building and fuel consumption estimations in each city center by using the degree-hours method. Since 50.8% of the total city center population in Turkey is considered, the total amounts of these estimations may be interpreted as a good indicator to give an idea about the energy requirements and fuel consumption for heating purposes in the buildings in all the city centers of Turkey.