This paper reports the development of VBFRED-IVY, a computational tool that is used to model and analyze the thermal effects of plants on buildings under Singapore climatic conditions. In VBFRED-IVY, the vegetation-air temperature and surface temperature of a planted wall and a non-planted wall are investigated respectively. Climatic data of Singapore are input to do the parametric testing. Then field measurements are carried on three planted walls in different orientations, and statistics method is applied to evaluate the simulation program. The results show that VBFRED-IVY is efficient.