In this study, heat losses were determined in the sample heat insulated and uninsulated buildings in Erzincan Province and heat loss economic analysis was made. As a result of the study, it is identified that total heat transfer surface area in the buildings in Erzincan is 2411189,77 m(2). 31,36 per cent of this area is insulated and 68,64 per cent is uninsulted. Because, the insulted buildings' insulation thicknesses differ, 4, 5 and 8 cm insulation thickness calculations were made according to the projects that was made in Erzincan before. Assuming that the insulated buildings built with 4 cm XPS, total heating cost was determined as 194914060,8 TL/year. If the uninsulated buildings have 4 cm XPS standart total annual heating cost would decrease to 85380229,75 TL/year and there would be 43,80 per cent saving. If insulation thicknesses is 5 cm and 8 cm, total annual saving respectively would be 41,49 per cent and 38,81 per cent.