A general overview of the system

Having decided to go ahead and build a home-brew system the first step was to decide exactly what I was hoping to achieve beyond the high-level term optimizing. I’ve made a list of the tasks I would like the system to perform and some of the outcomes I want the system to achieve:

1. It has to be cheap to build. As well as the obvious saving money outcome, I am hoping to demonstrate that anyone can build their own system and it will cost less than spending several hundred dollars per component on off the shelf kit. I am also hoping where commercial equipment does need to be bought e.g. a second pellet stove, the devices we choose are the best value for money (more on this later)
2. It needs to dump data somewhere I can retrieve it. I want to be able to review the temperature data and re-use it within the system. Having an average temperature for August and one for February and being able to compare these would be useful for example.
3. It needs to be self optimizing to a point. Using various algorithms and the above stored data, the system needs to be able to switch devices in the house on/off based upon a set of criteria such as: cost, performance, temperature, and in the case of a pellet stove, whether the stove is empty or not (for example if we are out and the stove runs out of pellets, what does the system use as a fail over?).
4. The system should be controlled via some sort of app that can be run on a PC, Mac and Linux/Unix device. This should include both mobile/tablet and regular devices. For example If I want to up the temperature in my home office whilst I’m at the supermarket, ready for when I get home, I should be able to do this via my iphone.
5. The device should be networkable, this can include both wi-fi and wired options.
6. The system should be safe and secure. Both from software perspective i.e. adequate network security and from a hardware safety perspective i.e. the home-brew thermostat isn’t going to fall off the wall.
7. It should save money on our electricity bill.
8. It should be extensible. If I wish to zone the system so that it draws its power from say a solar source, some other renewable or from a generator if the power goes out, switching over should be easy. If I wish to add more thermostats, pellets stoves, A/C or software apps this should be easy.

This allows me to break down the development stage into separate components and evaluate what technology I currently have, and what I will need to build and code the system. It also provides a list of criteria on what the system should achieve, so I can check along the way that each stage of development is hitting a goal.

My next step is to take stock of what I currently have and what I am going to need on both the hardware and software front.