This question is regarding the Energy and Atmosphere prerequisite Minimum Energy Performance and associated credit Optimize Energy Performance under the LEED v4 Interior Design and Construction rating system, specifically as it applies to Commercial Interiors projects.

Option 2: Prescriptive Compliance offers tenant improvement projects a certification path based on compliance with all mandatory and prescriptive requirements of ASHRAE 90.1-2010, along with connected lighting load reductions and the use of ENERGYSTAR equipment. In the case that an element of the design does not strictly meet the mandatory and prescriptive requirements of 90.1-2010, the project must utilize Option 1: Tenant Level Energy Simulation to demonstrate overall compliance by achieving at least 3% improvement in energy performance compared to the ASHRAE 90.1-2010 Appendix G baseline.

The LEED v4 Reference Guide for Interior Design and Construction indicates that “Areas and systems that are not part of the tenant scope of work are exempt (from meeting the above requirements). However, modifications to base building systems that serve the tenant space must comply with the ASHRAE 90.1-2010 prescriptive requirements if they are completed by or on behalf of the tenant.”

Can anyone clarify what constitutes a “modification” to areas and systems outside the tenant scope of work.
What precisely constitutes a modification to base building systems that serve the tenant space?
When modifications are made by or on behalf of the tenant, is only the modified component(s) subject to the requirements of 90.1-2010, or the whole system?

For example, in a building with an existing envelope system with a window to wall ratio in excess of 40%, or component U-values or solar heat gain coefficients not in compliance with Table 5.5, would the addition or relocation of a door or window, or installation of interior shading devices constitute a modification to the envelope system that requires the project to utilize Option 1 and energy modeling to show overall compliance?

As a second example, if a tenant is installing new variable air volume boxes, chilled beams, fan coil units, heat pumps, or other terminal air devices served with primary or outdoor air from by a base building air handling unit, does rebalancing or adjusting the operating parameters of this air handling unit constitute a modification which requires the existing unit to meet the prescriptive requirements of ASHRAE 90.1-2010, or the use of Option 1 and energy modeling to demonstrate overall compliance?