A sensor network has greater potential for performance improvement, due to its versatility and the ability to monitor a large geographical area. Recent advancement in wireless communication and electronics has enabled the development of low power consumption and low cost sensor network. There are different technical issues that researchers are currently resolving. Most of the attention however has been given to the routing protocols since they might differ depending on the application and network architecture. In this paper, the current state-of-art of sensor networks is captured. An energy efficient design proposal is suggested considering physical layer, data link layer and network layer. The simulator OMNeT++ was employed to evaluate the throughput, number of packet collisions of the network, and the network node duty cycle. The network was found to be stable even with node duty cycles as low as 0.19 percent, and able to handle an offered data throughput of 0.5 messages/node/hour. The node duty cycle was shown not to vary significantly with position in the tree network. Packet collisions were rare, validating the medium access function of theSAR protocol.