From the look of this you can tell that [Jasper Sikken] has some pretty interesting stuff going on to monitor the utilities in his home. But it’s important to note that this is a rental home. So adding sensors to the gas, water, and electric meters had to be done without making any type of permanent changes.
The module above is his own base PCB which accepts an mbed board to harvest and report on usage. His electric meter has an LED that will flash for every Watt hour that is used. He monitors that with a light dependent resistor, crafting a clever way to fasten it to the meter using four magnets. The water meter has a disc that makes one revolution for each liter of water that passes through it. Half of the disc is reflective so he uses a photoreflective sensor to keep track of that. And finally the gas meter has a reflective digit on one of the wheels. The sensor tracks each time this digit passes by, signifying 10 liters of gas used. He also monitors temperature which we’re sure comes in handy when trying to make sense of the data.