The contribution ratio of indoor climate (CRI) based on CFD was developed to estimate the individual contribution of heat factors to any location inside a room. With the index of CRI, a more precise building energy simulation or real-time systematic control can be expected, within the defined accuracy by means of CFD but with a much reduced calculation load. However most of the studies related to CRI involve forced convection airflow fields. Thus the purpose of this study is to make the CRI effective also in natural convection air flow fields. In this study, a new calculation method was proposed by means of setting a uniform heat sink, by which the steady calculation of CRI could be achieved. A CFD simulation coupled with convection and radiation has been performed in an atrium without air conditioning or ventilation. With the new method the CRI of the north wall was calculated and its influence to the air temperature at some representative locations was analyzed as an example. In addition the time response of CRI was also discussed in this paper.
