http://www.rpc.com.au/catalog/advanced_search_result.php?keywords=fan&submit2=GoGreg.L said:Vents are the way to go if you live in a cool area and want to save money. I have looked in the past for 12 or 24v dc vent fans but couldn't find any. (if anyone knows where to get one let me know) .If you have power connected you can put in an ordinary ac vent fan plus an inlet to let cool air in, with a timer so it only comes on a few hrs in the early morning. Fairly cheap and easy to install.