That is not an airconditioner, but an air cooler.
This works by evapouration or water and ice to lower the temparature. This typ0e of this is better than nothing but not that efficient and powerful.
For proper air chillling you will need something much more expensive:
http://www.argos.co.uk/static/Produc...er/1816822.htm or similar. These units are still portable, but you have a host for the hot air to be exhausted out of the window. True air conditioning will also control air humidity as well as temparature, hence myuse of the description air chilling.