Complex sensor network applications include multiple services such as collection, dissemination, time synchronization, and failure detection protocols. Many of these protocols require local state maintenance through periodic broadcasts which leads to high control overhead. Recent attempts to consolidate these broadcasts focus on piggybacking information into existing services but such tight coupling between protocols limits code reuse and interoperability of applications. We present Unified Broadcast (UB) which combines broadcasts from multiple protocols while maintaining a modular architecture of the network stack. UB is implemented as a transparent layer between the link and network layers, where it delays, schedules, and combines broadcasts from upper layer protocols before transmission on the wireless channel. Our empirical results in simulation and on a testbed show that UB can decrease the overall packet transmissions in the network by more than 60%, corresponding to more than 40% energy savings, without requiring new interfaces or affecting the correctness of the upper layer protocols.