A young relative is in student digs. A rented attic room which got unbearably hot last summer. We can spend up to £250 on a portable aircon for her as finals are approaching. The only windows the room has are large skylights so that might be an issue if it needs to be vented in some way. What would be an efficient machine to cool it so that it will be cooler at night? She keeps the blinds closed during the day and used a fan last year but it made little difference.