It's a whole other thing, the heat here in Australia (though 40C = pretty damn hot, really). Our houses are built to cope with it, they let the heat out and let the air move through freely. What they don't do is hold the heat well for the six weeks that it's bloody freezing in winter. When I was in England earlier this year, I couldn't get over how most of the windows in the houses I stayed in didn't even open all the way. It'd have to be pretty hard to cool a house without aircon or decent airflow from outside.