Energy Saving - Bubble Wrap Insulation

I have been trying different ways to save on heating and read an article on using bubble wrap to help insulate my windows. I have double glazing but gap between the glass panels is narrower than recommended so I thought I would try the bubble wrap idea.
I used bigger bubbles(20mm), bought on ebay, because the wrap was thicker and I thought it would look better. It was easy to do, simply spray the window with water and attach the wrap with the bubbles towards the windows.
The photo is my bathroom window.

[energy saving]
[bubble wrap insulation]