My Vision of a Home Smart Energy System

As I'm almost ready to start building the libraries and code to talk to various devices under development I thought this would be a good time to describe what I am hoping to build.

When I first embarked on this project my main focus was to save energy. My first project (after the Tweet-a-Watt) was to design and build a smart outlet/socket that would transmit current load and voltage data to a central 'coordinator' via a ZigBee wireless network and also allow me (through the coordinator) to switch the load on and off - a fancy programmable outlet really. I'm still working on this project and will report progress in future blogs. The initial aim of the smart outlet was to enable me to save money by switching loads off when not in use, as even in standby mode there can still be a noticeable energy draw to the device. However, it was pointed out to me that the ability to do this would save no more than perhaps a few $ per year - hardly worth the investment in time and materials. The area of major savings is in areas such as heating, air-conditioning, pool pump, etc. In these areas 100s, perhaps 1000s, of $ can potentially be saved annually through clever energy usage. This data point seemed to undermine the whole idea of a smart socket being used as part of an energy saving system. Why spend $20 on a device that will save you $1 per year?

It was something my wife said that made me realize that the focus on energy savings was too narrow. Being a Brit my wife (and therefore myself) is a Tea addict, and the only point at which she took interest in my Smart Energy System (SES) project was when she realized she might be able to program the kettle to switch on from her Blackberry shortly before getting up in the morning. Of course, attaching the kettle to a timer socket would nearly achieve the same thing as long as you got up at the same time every day! However, it made me realize that 'control' was the correct paradigm for the SES, NOT 'energy saving'. Of course you need some level of control to achieve energy savings, but the control paradigm is much broader than the energy saving one - it includes, for example, being able to switch the kettle on from your phone, which does not save energy at all, but offers some level of convenience (assuming you remembered to fill the kettle the night before!). This 'boiling the kettle' example may actually use more energy as I'm sure they'll be times when you reach over to your phone in the morning, switch the kettle on, and then fall back to sleep, and so the water might get boiled several times before you actually drag yourself out of the sack!

So the 'control' paradigm is my new focus. I want to be able to enable and disable any socket / outlet in my house from a central computer, or from a remote device like my iPhone (I'd like the ability to switch lighting on and off when I'm away from home - even better, I'd like a 'pretend-someone-is-at-home' autonomous mode!). I want to be able to collect data, such as current load, voltage, temperature, light levels, movement detection (which can be used for security as well as a useful input for developing energy-efficient configurations), etc. The method of communication between all the 'nodes' on this network will be via a ZigBee mesh network. I want to be able to view the status of my device network at any point locally and remotely. With all this data I will then be able to develop algorithms to, for example, minimize my heating and cooling needs, and so I want to be able to implement programmable energy schedules for any node on the network - so the network has to have a certain level of autonomy.

With such a network I will have the convenience of control, and be able to realize the benefits of energy saving configurations. So my wife will be happy as she'll be able to start the kettle boiling as she leaves the kids' school for home, and I will be happy because our bank account balance should look healthier (and I'd've built something pretty cool!).

So that's the challenge - stay tuned for progress reports... and if you have any thoughts on functionality you would like to see with such a network then feel free to comment. One thought I had was to use the control software and data set to develop algorithms that would aim to save enough money in a year to pay for a weekend away... once you have the control a whole new world of applications opens up...