Individual metering and charging have earlier been found to increase the tenant’s awareness of costs and have in most cases resulted in a saving behavior and energy conservation. In the new EU-directive2012/27/EU there is a decree of heat cost allocation in multi-apartment buildings and two techniques are mentioned to achieve this. The first technique mentioned is to mount an energy meter on the radiator circuit and one can measure the amount of heat (thermal energy) delivered to an apartment. The second technique is heat cost allocators mounted at each radiator. Both techniques result in that the delivered amount of heat to an apartment is measured, and this can be done fairly accurate. However, earlier studies have shown on large amount of heat leaking between adjacent apartments making heat cost allocation based on the measurement incorrect.The purpose of this study is to develop a cost-efficient method for estimating the size of heat adjacent apartments in multi-apartment buildings. The objective is to use these estimations for reallocation of heating costs due to heat transfers when measuring the delivered amount of heating energy to an apartment. The methodology used for the purpose is an earlier presented model as a base which has been further developed. The method is tested on an existing multi-apartment building with 16apartments. An attempt to verify the method has also been done with computer based simulations. The study demonstrates a possibility to make corrections for heat transfer between adjacent apartments in a fairly cost-efficient manner. However, the accuracy of the method has to be improved by more studies in other multi-apartment buildings.