Folks,

Some background: Working on a city hall project which is shooting for LEED silver. We are considering Option 2 Prescriptive for the minimum energy performance prerequisite. Option 2 requires compliance with mandatory requirements of 90.1-2010 and hvac+shw recommendations of Chapter 4 50% AEDG guide. We are looking at 50% AEDG for small to medium office buildings.

Question: The HVAC section of Chapter 4 AEDG for small to medium office buildings has 4 options. If we were to use prescriptive path, are we limited to these 4 systems? Let's say if the project decided to install an air source VRF system, will we be forced to use whole building energy modeling path (I understand Option 1 would be better for a system like VRF and likely result in higher points but lets ignore that for this discussion). Or can we just show that the VRF system meets the efficiency requirements of 90.1-2010 and that would be acceptable for the prerequisite?