The opportunistic large array (OLA) system is a novel method used to perform cooperative transmission in large sensor networks. Cooperation is obtained by a simple transmission strategy based on the integrate-and-fire model in biological swarms. The method utilizes the accumulation of signals from simultaneously transmitting nodes, therefore, it is energy efficient compared to conventional point-to-point networks due to the power accumulation effect. In this paper, we study the gain in energy-savings that we can obtain by using OLA. We analyze particular network topologies to obtain the asymptotic behavior of the minimum energy solution and verify our analysis through numerical simulations. Our discussions show that with cooperative transmission, network flooding can be reliably obtained with low average power per node compared to standard multi-hop networks.