Home Automation is a topic that interests me and is as such something I've been dabbling in for a number of years. The concept is simple - network your home's electrical devices together, allowing the state of each to be remotely manipulated.
Why bother?
The most obvious benefit this brings is being able to control them using a remote without getting off the sofa or out of bed. You control your TV by remote already, so why not the lights?
Whilst it could be seen as being rather lazy there's something nice about being able to check you turned everything off downstairs from bed and being able to turn fans on throughout the house without opening your eyes when you wake up too hot in summer.
The real fun and automation part starts when you bring a computer into the mix, allowing it to control devices automatically dependant on the time of day, whether you are home, what you're doing etc. This can save you electricity by turning off devices not in use, taking devices completely out of standby (i.e. turning them off at the mains), setting brightness of lights according to how much daylight there is etc. It can also help with security - by learning your preferred lighting patterns it can replicate them each day whilst you are on holiday.
We use ours mainly to create macros such as lighting scenes, that can be activated from one button press. When we go to bed we press "Downstairs Off" (turn off lights, AV gear etc) and "Upstairs On" (turn on our bedroom lights and dim to desired level). The computer turns the garden lighting off automatically at 11.30pm; having turned it on at sunset (the time of which it calculates each day). "Watch DVD" on our lounge remote turns on the TV, home cinema amp, sub, blu-ray player, sets the inputs accordingly and dims the lights lower than we have them for "Watch TV". As well as remotes in each room we have switch panels on walls for activating common macros:
We have (but have not integrated yet) proximity sensors, that allow the computer for instance to turn hallway lighting on at 25% if someone gets up at night. A dirty little secret
I have a dirty little secret. Well, actually I have several, but the one of relevance to this post is the fetish I have for lighting.
I like warm sunlight the most, but failing that; decent functional and mood lighting, along with sparkly things and pin pricks of light.
Including LEDs there are currently 25 bulbs in the kitchen, 12 in the lounge, 14 in the hallways, 29 in my study, 446 in our bedroom, 19 in other rooms and 202 outside. This total of 745 and excludes all the candles and the several thousand 'stars' generated by my 2 laser projectors.
You'll be pleased to know that most of the lights are low energy and less than 1 watt each - I'm not a complete eco terrorist.
What else?
Some people automate their blinds and curtains, however the price is pretty astronomical (starting at £300 for a small window). Heating system control is common too, but I don't quite trust a computer with that - the same goes for door locks. The security system used to link in (which being connected to the phone line meant I could dial in and change settings from a mobile phone), but in practice this wasn't overly useful.
I'm not so fussed on AV distribution. I don't illegally download movies, so don't need to to stream from PC to TV (though supposidly I can do this on my Bravia anyway). I used to have a MythTV server in my batchelor pad for streaming music and recording/timeshifting TV, but as I like my neighbours I tend to wander round the house with wireless Sennheiser headphones on instead these days.
My previous HA / AV server was an ultra quiet / mostly passively cooled Linux box. I didn't like the fact that it was drawing so much power constantly though, so now I don't run MythTV I've switched to a small embedded device instead.
We have an energy monitoring device too, which can be hooked up to a PC every now and then and plot graphs / calculate costs. Though currently broken when it works it displays our current wattage and glows a different colour accordingly, so we can see at a glance when we leave the house whether we've left anything switched on (also useful for seeing if the oven is still on when sitting in the lounge).
Costs?
There a several different technologies available that allow you to achieve these things, with varying levels of success and reliability.
The most reliable systems use their own cabling and cost £10,000 to £100,000+ to be installed and maintained (examples here). As a luxury product these tend to only be found in the homes of rich and famous.
Falling into neither of these categories and having 10 inch thick walls that don't make cabling much fun we currently use a more basic technology called X10, which uses RF for sensors/remotes and the house's existing powerline cabling for communication between devices. The downside of this is that it's slower and not 100% reliable (part of the reason why I'm not using it for heating).
X10 has been around longer than I have and the complete system so far has cost about £700 (much of it purchased over time, second hand from ebay). As a modular solution you can get started for £100-£200 and build on it from there. Some of the modules need embedding in walls / ceilings, but most can be plugged into sockets, such as this one:
The modules are undoubtedly overpriced for what they are - if mass produced they shouldn't cost more than £250 for an average house. I don't fully understand why, given the technology is 35 years old its use isn't more widespread. Aimed squarely at the hobbiest end of the market rather than luxury living the modules and remotes pretty damned ugly. As such as we use IR dimmers for our main lights, then a Logitech Harmony remote in the lounge and an IR->X10 converter for other devices.
There are cheaper, more restricted and debatably crapper systems available, such as Domia Lite, which I dabbled with for a while but ultimately got rid of. If you just want to turn devices on/off on a cheap looking remote you can pay as little as £3 per socket. You won't however been able to add computer control with these systems or do anything more fancy.
Some people buy £500+ remotes and have £1000+ touchscreens embedded into their walls. I'm a bit more budget constrained than that, so am looking forward to the Apple iPad being released, which as well as a general web browser whilst sitting on the sofa would make a stunning HA remote control.
I've always been interested in this area to. Unfortunately my technical skills are a little lacking, so the home automation runs to few timer controlled lights and a remote with I used to switch the TV totally off at the mains.