Software for Central Heating Control

[rowan@xxxxxxxxxxxxxxxxxxxxx]

I'm having a loft conversion done at present, and I'd like to take the
opportunity to upgrade my central heating control system, which is
currently pretty dumb (3-on 3-off per day controller for hot water and
heating, with thermostatic radiator valves). I'm looking for some
software that will let me run much more sophisticated control
algorithms. Some of the things I'd like to be able to do are:
 - control three heating zones plus hot water
 - allow different control temperatures for each zone at different
times of day and days of the week
 - correct for outside temperature, wind speed and direction etc.
 - don't heat rooms when they are unoccupied
 - don't heat rooms when the windows are open
 - heat only as much water as is expected to be required for the time
of day (i.e. don't heat a full tank unless people are expected to be
bathing or the washing is being done)
 - use oil, off-peak electricity and full-price electricity in the most
cost effective manner
 - automatically adjust boiler operating temperature for optimum
efficiency (i.e. lower the boiler temperature when the heat demand is
lower)
 - learn house warm-up time under various conditions and come on "just
in time" to achieve the required temperature
 - easy to use and flexible manual override facilities via wall-mounted
control panels, a web based interface or by phone (e.g. hotter, cooler,
on, off, come on for 1 hour etc.)
 - full logging of temperatures, boiler firing times and valve opening
times so that performance can be analysed and improved
 - interface to temperature sensors, e.g. Dallas One-wire sensors
My vision is to run the control software on a small solid state single
board computer with the necessary I/O (interface to temperature and
other sensors, mains relays for zone valves and pumps, wall mounted
control panels, web server for network based contol etc.), with the
control program developed on a PC and downloaded to the SBC when the
algorithms need to change.
What software exists which can help implement this sort of control?
What languages are best for implementing the algoithms?
Who else is working in this field?
What is the best hardware?

Thanks for your help - Rowan