Combination of New Build and Existing

Hello, I am working on the major renovation of an existing office building and new construction of a new entrance/reception atrium. Both aspects are being assessed under the one LEED submission, as both share the same physical space (high level walkways from the office building are located in the atrium at high level). As such the ASHRAE 90.1-2007 model comprises both buildings. My question is whether the model needs to be rotated for the 0, 90, 180 & 270deg rotations. From the guidance provided above existing buildings do not need to be rotated. However as there is an element of new build here, how should we deal with it? The existing element is much greater than the new build in terms of floor area. We have worked off the basis that we must rotate the model to date, however can we justify not rotating, as the orientation of the new build is effectively dictated by the existing (follows the outline of the existing building). Thanks!