Transmission reliability and energy consumptions are two critical concerns associated with wireless sensor network (WSN) design for a long time and continuous operation. With the increase in reliability of the transmission, the energy consumption increases by affecting the efficiency of the network. This paper proposes the Schedule based Collision Avoidance (SCA) algorithm for finding the tradeoff between reliability and energy efficiency by fusion of CSMA/CA and TDMA techniques in Zigbee/ IEEE802.15.4. It uses the multi-path data propagation for collision avoidance and effective utilization of the channel providing efficient energy consumption. It analyses different scheduling schemes to provide an appropriate solution for reducing collisions and improving network lifetime.