Here is an interresting article for everybody interrested in home automation to read:
How to Choose a Home Automation System
http://hometoys.com/article.php4?displayid=762
"A really interesting change occurs when home automation is installed. You begin to treat your home as one big unified system instead of a collection of smaller unrelated systems. When this happens, the possibilities and “what if’s” start to surface. This is where the fun begins!"
This part of article gives a good overview of the different control technology options:
"STEP #5 – Pick your control technologies.
Sadly, this step is often taken long before a clear understanding of the system is developed. Those who make this mistake usually end up wasting a lot of time and money. Remember: it’s much easier to choose technologies that fit your needs than it is to adjust your needs to fit your technology choices! As you review the options below, choose the technologies that best fit your needs and add them to your automation list.
Here are some common automation control technologies to consider:
Hard-wired – Wires (typically CAT5 cables) are run from a sub-system controller to each device. Typical application: Lighting and security PROs: These systems are very reliable and offer lightning-fast response. CONs: The devices and system controllers are often very expensive. Installation into existing homes can also be very expensive.
Powerline – Control signals are transmitted through the existing power lines of the home. Typical application: Lighting, appliances, HVAC, Motion sensors PROs: These systems are significantly less expensive than hard-wired systems and wall switches and lamp modules are generally very easy to install. CONs: Power line conditions in the home can fluctuate significantly and affect performance and reliability.
Wireless – Control signals are sent via radio frequency transmissions. Typical application: Lighting, appliances, HVAC, Motion sensors, Cameras PROs: These systems are significantly less expensive than hard-wired systems and wall switches and lamp modules are generally very easy to install. Reliability is very close to that of hard-wired systems. CONs: Since the standards based technologies are relatively young, availability of many devices is limited.
Serial (RS232, RS485) – Control signals are transmitted through serial cables. Typical application: Security, HVAC, Digital I/O (including sensors - temp, humidity, light) PROs: serial communications are very reliable and are used extensively in the security and HVAC industries. CONs: RS-232 serial cable runs typically cannot exceed 50 feet and installation into existing homes can also be very expensive or difficult to do.
Ethernet (Wired/Wireless Network) – Control signals are transmitted through network wiring. Typical application: Security, Digital I/O (including sensors), Infrared, Cameras PROs: Network communications are very fast and very reliable and are used extensively in the I.T. industry. Networked devices can sometimes be located outside the local network and used in remote locations. CONs: Installation into existing homes can be expensive if wireless network technologies cannot be used. There are very few devices available with a network interface.
Infrared (IR) – Control signals are sent via infrared (IR) transmissions. Typical application: Home Entertainment Equipment, Shade/Blind controllers PROs: IR control allows easy control of most TVs, DVD players and audio systems. CONs: IR signals are only reliable for ‘line of sight’ transmissions. Extending range for these devices requires additional equipment with added complexity and expense.
NOTE: Depending on your needs, you may need to mix multiple control technologies. If the controller you’ve chosen (in step #4) doesn’t allow enough flexibility to support all the technologies you require, you may need to backtrack and reconsider that choice."