Yeah but it only works when the inside is warm and the outside is cold.
For example:
Hot summer days, followed by colder summer days.
The buildings were warmed up by the hot summer days/sun and need lots of days to cool down.
Thus the inside of the buildings still warm up.
So open both doors and let the colder air come in... too cool things down.
That's what I was talking about mostly ;) :)
Other situation can ofcourse be hot computers and hot people making the room warm/hot :)
Or even both situations at the same time ! ;)
However during hot hot hot hot summer days... people are switching to air conditioning systems which require power ;)
Bye, Skybuck.