Entropy generation during natural convection within tilted square cavity inclined with different angles (φ = 30°and 75 °) for various thermal boundary conditions (case 1: isothermal heating and case 2: non-isothermal heating) has been studied. Simulations are carried out over a range of parameters: Rayleigh number (103 ≤ Ra ≤ 105) and Prandtl numbers (Pr = 0.025 and 998.24). The numerical results are presented in terms of isotherms (θ), streamlines (ψ), entropy generation due to heat transfer (S θ) and fluid friction (S ψ). Heating strategy is energy efficient for case 2 (non-isothermal heating) due to its less total entropy generation with reasonable heat transfer rate, irrespective of Pr. © 2014 Taylor and Francis Group, LLC.