Not sure this is a useful comparison?

Chicago average temperature: http://www.holiday-weather.com/chicago/averages/

Sydney average temperature: http://www.holiday-weather.com/sydney/averages/

In Sydney, your primary concern is heat. In Chicago, your primary concern is cold. They have different strategies to combat. I.e. good blinds could cut your cooling bill 50% in Sydney. Good blinds will not make a dent in your Chicago bill..