Site Orientation
This is critical to efficient design  but, efficient for what ..

A view of the back patio in the afternoon - looking NW.

The trellis was an important part of the design that we almost value-engineered out. It helps to keep the patio cool during summer.

Mature trees and other aspects of the landscape are also important in creating and energy efficient design. Shading the West side of the house from afternoon soon can help keep the room temperatures moderated.

There are many reasons to consider "site orientation" but, the one I have focused on is a site orientation that contributes to a passive solar design. In other words, an orientation that allows for the suns energy to positively influence the house system.

Do I have to have south facing property ?

South facing property +/- 15 degrees is the ideal orientation. But, there are other orientations that can be advantageous to the design of  a passive solar house system.

At PDR, the original house line faced largely East-West.  This was ideal for our goal of trying to harness the Sun's energy to warm and illuminate our house as well as cool the house on summer evenings by taking advantage of the prevailing winds. We also wanted to use solar thermal (hot water) and solar electricity (photovoltaic). 

Sometimes you will have little opportunity to maximize site orientation, but if you are starting with a lot, looking for a house or remodeling you have a great opportunity to make nature work for you or at least to create a partnership.