If you were building a new house, what could you do to make it an energy-efficient structure?

You could use stuff like solar panels or windmills or if you are next to a river i forget the name but its like a wheel but with groves in it and when the water flows in it it turns and while it turns it either A should be hoked up to a pulley or B it should be making its own electricity all of these will also help kill global warming if you believe in that if not it will help you save money also for water you could put out a bucket or something and catch rain water because rain is the cleanest water on earth 

Put in energy-efficient insulation or use energy-efficient construction materials.

Hope that helped!