The investigation of laminar natural convection in vertical obstructed channels is conducted using an h-adaptive finite element algorithm. The adaptive model uses an L-2 norm based a-posteriori error estimator with a semi-implicit, time-stepping projection technique. The advection terms are treated using an explicit Adams Bashforth method while the diffusion terms are advanced by an implicit Euler scheme. By using the adaptive algorithm, mesh independent studies can be avoided. Results are obtained for thermal and flow patterns including average Nusselt numbers for different parameters (Rayleigh number, aspect ratio and locations of obstructions) in both smooth and obstructed channels. (C) 2009 Elsevier Ltd. All rights reserved.