The first workshop on Engineering Energy Efficient Wireless Sensor Networks aims at bringing together academics and practitioners from different areas (such as, software engineering, system engineering, energy efficiency, embedded systems) to promote cross-layer design, validation, and implementation of energy efficient WSNs. Papers where WSNs take advantage of pervasive technologies such as mobile technologies, Internet of Things, RFIDs and Cyber Physical Systems (CPS) are also encouraged. EEEWSN encourages practitioners and industries to submit real-world case studies. Experiences gained in these deployments can be crucial for the research community. Results and settings can be used to refine the assumptions made when designing, validating and implementing WSNs.