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Abstract-Energy wastage in buildings is to be minimized to reduce the carbon footprint of electricity. Wireless sensor and actor networks (WSAN) have been providing solutions for effective energy management within buildings. In this paper, we present a decisive server based context aware energy management system for smart buildings through Cyber Physical System (CPS) models. A layered architecture for building energy management is proposed to enhance scalability of the system. Heterogeneous wireless network based multiple radio gateway is proposed and implemented to make the system more adaptive to different applications catering to variable data rates. A smart room test bed is deployed in the IIT Hyderabad campus, where the decisive server collects various physical parameters through sensors, and based on the context generates wireless control messages to power electronics based actuators. Integrating context awareness into the system increases the efficiency in terms of energy savings and was observed to be significant, around 30%. The paper also presents a detailed analysis on the turnaround time required to realise the real saving after recovering investments. Applications are developed to integrate smart phones and tabloids providing web enablement to the end user. In this paper, each of the sensors and actuators in the smart room are associated with a state machine, which enables modelling of the system using Hybrid automata for future scope of applications.

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Abstract-Design of energy efficient wireless networks is the primary research goal for evolving billion device applications like Internet of Things (IoT), smart grids and Cyber Physical Systems (CPS). Energy efficient models can reduce megawatts of power through out globe thereby reducing carbon foot print by improving overall network lifetime of large scale networks. Recent advances in physical layer have optimized energy consumption of IEEE 802.15.4 Physical layer, but energy efficiency of MAC and network layers is also essential to realise Green wireless networks. Though anycast multi-hop communication is initiated by many recent researchers by obtaining reliability, delay and energy expressions, still there is no model that captures relay nodes state wise behaviour effectively. In this paper a new energy model with 3-dimensional Markov MAC model with generalized anycast routing and state behaviour is proposed and developed for asynchronous wireless ad hoc networks. Proposed state behaviour of node model has consideration of MAC and network parameters like minimum backoff exponent, maximum backoff stages and retries along with network parameters like packet length, wake up rate, Sleep, Idle-Listen, Active-Tx and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) states. Results show that total energy of derived model depends on many network and MAC parameters. Affect of most of the considered parameters are analysed with simulation results. Total energy of the multi-hop network reduced to 25% with variation in minimum backoff exponent and increased by 45% with increase in packet length. It is observed that derived analytical energy model better fits with most of the parameters that affects energy.

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