Wireless Sensor Networks

I'm currently looking at using wireless sensor networks around the home as part of my PhD. Currently I'm investigating the different types of sensors that can be used in these scenarios. The first type is energy monitoring, notes on which can be found here. The second is simple environment monitoring, i.e. temperature and light. The final type is motion, based of PIR sensors, more specifically the pyroelectric infrared sensor found inside the PIR device (RE200B).