Chances are you have seen my video, explaining passive house in 90 seconds.
I'm glad about how many people it has reached and how it has helped broaden the understanding of what passive houses are. To this day there are a few things that bug me about it though, but it would be too cumbersome to fix the video and so it stays as it is. (If I was Mr. Sieber, my physics teacher in highschool, I'd say "I just wanted to make sure you are paying attention.")
Undoubtedly the big Zinger: the sequence of the different steps to achieve maximum energy savings in buildings.
1.) Air Tightness first, then
2.) Insulation levels, then all the others.
Why should airtightness be first?
1.) From an energy conservancy point of view: Without spending more on materials (or minimally more), energy consumption for heating is being drastically reduced. You are already taping your joints in your vapor barrier or retarder (membranes or OSB), so it may as well be done thoroughly
2.) From a healthy building point of view: it avoids damage due to condensation in your walls - moist indoor air being driven into the wall cavity and condensing on cold surfaces, then leading to mold and rot
3.) From a comfort point of view: cold air streaming right through walls (ie: electrical outlets), leaky window and doors seals can creat nasty drafts.
In order to save the same amount of energy using the insulation levels, you'd have to drastically increase the amount of insulation, which will also increase the need for other materials such as lumber. Oh and BTW, the issue of the air leakages possible causing condensation and damage in the walls still prevails.