The main objective of the present study is to model, analyze and assess a building heating system along with its main components through advanced low exergy method. This method is shortly called ADLOWEX and combines advanced exergy (AD) with low exergy (LOWEX) for the first time by the authors. In the ADLOWEX analysis method, a building heating system is investigated from the energy production to the building envelope by dividing exergy destructions into four basic parts, namely endogenous, exogenous, avoidable and unavoidable exergy destruction rates first. The mexogenous exergy destructions for all components are determined. The endogenous and exogenous exergy destructions of the system are 27% and 73% while the avoidable and unavoidable exergy destructions are 26.2% and 73.8%, respectively. (C) 2014 Elsevier B.V. All rights reserved.