I had the same issue, the only solution i could find in order not to compromise the battery life is to create a new battery mode.
Just choose a maximum CPU rate and yes it slows the computer but it's not a problem for most usage. You should choose 40%, that's the best compromise between performance, noise and battery life. I can even reach 10h usage on one charge with low brightness.
If you find any other solution in order to tell the system to keep the heat without turning on the fan or just at a precise temperature let me know.
Here's a screen capture (in french) but you could find it easily.
http://i68.tinypic.com/11scev6.png