Although there a number of instructables on this site in this very subject, it is very exciting for me as it is my first project. Because of the layout of the rooms (see picture attached), I had to resort to more than IR to control the two separate Arduino boards. A 433 Mhz Tx / Rx provides thee required transmission between the two switch board.
It was interesting to see my first project turn out into something which I know will be used every day at home. Overall I am delighted at the results.
The Tx board comprised of :-
(a) Arduino Uno
(b) Kayees IR receiver
(c) 433 MHz RF Transmitter
(d) a set of four relays operated at 5 volts and
(e) some bare PCB, wires and soldering iron
The Rx board comprised of pretty much the same things except that the 433 MHz RF Transmitter was replaced by the 433 MHz RF Receiver.