The Collaborative International Dictionary of English v.0.48:

drafty \draft"y\ adj.
   not airtight; allowing in currents of air, especially
   uncomfortably cold air; -- of buildings.

   Syn: draughty.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

drafty
    adj 1: not airtight [syn: drafty, draughty]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "drafty":
   aeolian, airish, airy, blasty, blowy, blustering, blusterous,
   blustery, boreal, breezy, brisk, favonian, flawy, fresh, gusty,
   puffy, squally, windy