One important element of designing a home to be energy efficient is the proper design for window overhangs to provide adequate sun in the winter, and sun shielding in the summer. This will provide solar heat entrance during the winter to minimize heating demands, and will block solar intrusion in the summer to minimize cooling demands.
Here is a simple online tool to estimate the window shading you need for various windows. You will need your latitude and the direction and size of the window.
