Not sure if this is what you are looking for:
The Canadian Association of Professional Apiculturalists wrote paper about 'The Biology and Management of Colonies in Winter'. On page 3 they have a short summary and diagram about 'the amount of honey consumed (winter weight loss), spring adult populations and nosema levels among colonies with different types of entrances'. Sorry, I couldn't find the original Alberta study online.
Quote from paper:
"The best way to vent extra moisture from wintering colonies is with an upper entrance. This entrance is very important! A study from northern Alberta, for example, demonstrated that either a 1 x 1.5 cm top entrance built into the inner cover or a 2.5 cm diameter hole in drilled into the middle of the upper brood box greatly increased colony strength, health and decreased the consumption of honey stores (Fig. 7)."
Figure 7 compares:
"1) bottom and top entrances 1 x 1.5 cm each,
2) bottom (1 x 1.5 cm) and top (2.5 cm dia in middle of 2nd chamber),
3) bottom and side (1 x 1.5 cm each) and
4) fully open bottom entrance and no top (from Szabo 1982)."http://www.capabees.com/main/files/pdf/winteringpdf.pdf