Bob Hutchins in central Texas
>In Feb '88 I stood inside a very large igloo built lakeside at Chateau Lake Louise in Alberta. I'm sure it was not a typical native structure, but I was struck by the immediate rise in temperature inside even though there was no fire. The heat from 5 or 6 people inside the structure was captured and retained (IIRC, there was no smoke hole or other roof opening) so efficiently that it was uncomfortable to remain inside without removing one's coat. The experience gave me a profound respect for the people who derived the design and used it so effectively.
Thanks, again, for a great question.