Certifying New Addition, excluding Existing Building

A client is preparing for the development and design of a sizeable New Addition to an Existing Facility in Europe. The Existing Facility was constructed recently (within the last 5 years), but it was not LEED certified, nor is certification for that structure desired. The New Addition will be physically connected to the Existing Building. Although there is much explanation in the "supplemental guidance", and there are questions and explanations here in LEEDuser's forum, I would like to try to simplify my own questions and thereby, hopefully the responses: 1. Is it required that the HVAC system of the New Addition be separate and independent from the Existing Building? 2. Is it required that there be a physical barrier - a wall - between the New Addition and Existing Building? The client is willing to implement an independent HVAC system (although we would like to have the option available for a combined HVAC system should it prove more efficient, eg sustainable), but a wall separating the two spaces will not be possible due to functional needs of the facility. We realize it is required to independently meter water and electrical consumption of the New Addition for compliance with the MPR #6. I would greatly appreciate insight and opinions. Thank you - Kris