TABLE OF CONTENTS The elements of a heating or cooling load consist of quantities that can be normalized on the basis of either the floor area or the outside wall area. All quantities that relate to internal gains lend themselves to normalization on floor area, while those quantities relating to envelope gains/losses can be normalized on the external wall area. Thus, one important geometric aspect of a zone is the exterior wall area to floor area ratio. For heating loads this parameter can characterize a zone; however, for cooling loads there are additional considerations.
In particular, the location of a zone within the building becomes important for the solar aspects of the outside zones. When solar considerations are included, a multistory rectangular building has 27 unique locations for a zone. The easiest way to visualize this is to consider a Rubik's cube. The three layers represent three floors, ground, middle, and top. The corner elements represent the corner zones. The outside middle elements on each floor represent zones facing in each of the four directions but having only one exposed surface, and the very center element (which is not visible in the cube) represents an internal zone. The top layer, of course, has a roof on top, while the bottom layer has some sort of communication with the ground.
Continuing the analogy, it is easy to see that a single-story building would only have nine unique locations, and a two-story building would have eighteen.
