Right back again. Lets get this sorted. I'll take Juan's comments because he is obviously an insider and apart from the odd bias here and there, his posts are normally factual.
This is about passenger and crew comfort. Some pilots have expressed concern during the summer that the cabin temperature on the crew boarding is too high, sometimes in the mid to high 30s. This is a safety related issue - you are foolish to board passengers onto an aircraft if the cabin temp is above 30C,
The technical answer to that is really quite simple.
a)lf this is genuinely a safety related, passenger and crew comfort issue, you have no choice, packs on. Blinds will assist a little but in most cases you have not got a chance in hell of getting it down to your "safety level"
And if it is a safety issue, why should crew risk their safety when there are packs on board to do exactly that job?
So is it a safety issue or isn't it?
And I remind you, blinds up or down at night makes no difference whatsoever.
Now if it isn't a safety issue but a cost cutting exercise then Captains should be aware of that and they should also be aware that the temp saving is minimal, pax wouldn't notice the difference, but cost savings are to be had.
But then again we are talking about saving the fuel required to run the apu. That is tax free aviation fuel which actually costs a few pence a litre. In reality we are squabbling over approximately 100-300 quid to keep a 747 cool during a turnaround.
Peanuts in comparison to ticket sales and a cool cabin that an appreciative customer may well take into account when making their next booking.