The hardware installation of this system comprises three parts:

1. •Sensing Modules – For the measurement of voltage and current in each household appliance
   

2. •Control Modules – For the automatic switch on/off of appliances
   

3. •Central Processing Module – To process data, send/receive information from the producer, and display usage data to customers
   

Fig 1: Overview of the hardware modules and information flow, regulated by the Central Processing Module

For the Sensing Modules, the primary concern is the electrical characteristics of the appliances in the house. For each individual appliance, the REACT system needs to constantly monitor the voltage and current to determine the real-time power being consumed. Several household monitoring systems in the market have already developed devices which monitor power consumption in household appliances, for instance the iMeter Solo by Insteon (8), and the energy monitoring capability that we will utilise will not differ too greatly. We propose to use devices which plug in to power sockets, and have the household appliances plug in to the Sensing Modules. This way all power can be measured directly through the Sensing Modules. The information on energy consumption will be transmitted to the processing module through a ZigBee radio device housed in each Sensing Module. The ZigBee wireless communication standard was chosen (as opposed to WiFi) due to its cheaper cost, low power usage, and ease of use (9).

The Control Module turns each appliance on/off through wireless commands received from the Central Processing Module. The implementation of a Control Module which merely supplies power to an appliance is a relatively trivial task, and can be combined with the hardware in the sensing module, as observed in Belkin’s WeMo Home Control Switch (10). This will suffice for simple appliances, such as lighting or heating. However, to be truly ‘smart,’ the Control Module should be tailored for specific appliances. For example, the Control Module of a washing machine should be able to start the washing machine and apply the right washing settings autonomously. As this would require substantial standardisation among appliance manufacturers, it is out of the scope of our project at the moment. However, it is sufficient to say that remote-controlled smart appliances do currently exist and our system can potentially incorporate them in the future (11).

The Central Processing Module is the brain of the REACT system. It generally performs the six tasks as illustrated in Fig 1. By considering the hardware requirements to perform the tasks above, it is reasonable to presume that they can be executed by a middle-class tablet or smartphone, with a specialised application. If the software can be run on a tablet (which already belongs to the consumer) then this would reduce hardware costs, as they would only need to purchase the components to interface with the ZigBee network (such as a dock). To target consumers who do not already own tablets, an inexpensive, dedicated hardware solution utilising similar components found in tablets could also be made available.