The aim of this research is to investigate the effectiveness of vertical vegetation in terms of energy savings for a residential facility situated at KAIST campus. The research has been established through analyzing different building orientations to find out the most suitable combination of vegetation and orientation for reduced heating and cooling energy consumption. A simulation model has been developed where leaf area index, one of the contributing plant physiological parameters for improving building thermal performance, has been incorporated as per seasonal variations. This allowed observing thermal performance patterns of green wall throughout the year. Approximately 60 % savings in heating energy and 31 % increase in overall energy efficiency were achieved with the non-insulated studied building case, and the results showed extreme weather conditions lead to greater energy savings in winter. In cooling season, plant layers were found to be less effective in terms of facade thermal performance especially during relatively higher temperature period, with an average of 17 % cooling energy savings. The North-oriented green wall was observed to be the most effective in increasing heating energy efficiency, while the East-oriented wall was observed to be greatest in cooling energy savings. A higher LAI value proved to be beneficial in improving both heating and cooling energy performance for the studied building.