Here is a PDF article from The Journal of Light Construction on air sealing aspects of dormers and other characteristics of the 1-1/2 story house.
(https://i56.photobucket.com/albums/g166/jraabe/1-story.jpg)
http://www.jlconline.com/cgi-local/view.pdf/b1af0ff52a4cc7a5d5ffeb6d2a533c9c/www.jlconline.com/cgi-bin/jlconline.storefront/4a8ecd251dec606427170a32100a0668
Note: I am not certain how long this article will continue to be available on-line.