<p>Impact of cavity and hole configurations on thermal performance in interconnected enclosures have been investigated numerically in laminar regimes. The study is carried out for varying Rayleigh numbers ranging from (7 × 10³ to 2.5 × 10⁶) and also for emissivity values from 0 to 1. The effects of various cavity geometries, holes geometries, holes dimensions, and cavity holes arrangements on heat transfer attributes have been evaluated. In this study, the algebraic multi-grid solver of Ansys fluent is used to perform the simulations of the Navier–Stokes equation combined with the energy equation in the computational domain. A thorough grid sensitivity analysis and validation of the numerical methodology used in the simulation are carried out. The results are validated against the published data in the literature. It is seen that as the holes radius is increased, the value of the Nusselt number also increases significantly. However, Nusselt number gets saturated beyond 15 mm, thereafter no significant increase in the Nusselt number is observed. It is found that the circular hole of 15 mm radius at 45° orientations on an alternate interconnected cavity exhibits the highest rate of heat transfer. The coupled free convection and thermal radiation heat transfer tends to significantly enhance the total rate of heat transfer is ∼ 110% compared to pure free convection. Correlations are established to forecast the Nusselt number for vertical annular interconnected cavities as a function of cavity width to cylinder diameter ratio (w/d) and Rayleigh number (Ra), using least square linear regression method.</p>