I have decided to install a small unit at the front door of the apartment which activates the aircon/lights etc when guests are in the property rather than chance them leaving the aircon running all day and night - even when they are out. It is similar to those used in hotel bedrooms. Now, to be fair, it doesn't take a genius to work out that you simply remove the key from the fob and, hey presto, you have overcome the system but I intend to loop a small combination padlock between the key and the fob so that this can't be done. Or at least unless some anorak spends half his holiday twiddling with a padlock to work out the combination....I bough the unit from a company called Diyses if anyone else is thinking of renting out their property and wants one. Just a thought.