The Collaborative International Dictionary of English v.0.48:

icehouse \ice"house`\ n.
   a building used for storing ice, especially one built partly
   below ground and insulated so as to preserve ice obtained
   during the winter from frozen lakes or rivers.
   [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

icehouse
    n 1: a house for storing ice