We are modeling a new building for EAc1. There is a small existing building attached to this new building. It is less than 9% of the area of the two buildings combined. Part of the interior will be renovated which is less than 4% of the area of the two buildings combined.
We are considering whether or not to include this building in the LEED application.

The envelope will not be modified. The HVAC system and the lighting system will not be modified.

Per 90.1-2007 Appendix G1.2 “All the requirements of sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4 are met. These sections contain the mandatory provisions of the standard and are prerequisites for this rating method.”

According to 90.1-2007 Table G3.1.5 Building Envelope under Baseline Building Performance "5f. Existing Buildings. For existing building envelopes, the baseline building design shall reflect existing conditions prior to any revisions that are part of the scope of work being evaluated."

In the same section under Proposed Building Performance "All components of the building envelope in the proposed design shall be modeled as shown on the architectural drawings or as built for existing building envelopes".

I can see no requirement that the baseline or proposed building envelope for existing buildings need meet 90.1-2007 requirements if the envelope is not in the scope of work.

In Table G3.1.10 HVAC Systems under the Baseline Building Performance "The HVAC system(s) in the baseline building design shall be of the type and description specified in Section G3.1.1….." It is clear here that the baseline building HVAC system needs to meet 90.1-2007 requirements. It does not say only if the HVAC system is in the scope of work.

The Proposed Building Performance section G3.1.10a does state that "Where a complete HVAC system exists, the model shall reflect the actual system type".

In Table G3.1.6 Lighting under the Baseline Building Performance “Lighting power in the baseline building design shall be determined using the same categorization procedure and categories as the proposed design with the lighting power set to the maximum for the corresponding method and category in section 9.2.” And under the same section Proposed Building Performance “6a-Where a complete lighting system exists, the lighting power for each thermal block shall be used in the model.”

The requirements as written in the LEED documentation are:

“For all elements included in the architect's scope of work for the project
building, the project building design complies with all ASHRAE
Standard 90.1-2007 mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4,
9.4 and 10.4), and the information provided regarding the Proposed
Case energy model in Section 1.4 is consistent with the Building Design.”

“For all elements included in the mechanical engineer's scope of work for
the project building, the project building design complies with all
ASHRAE Standard 90.1-2007 mandatory provisions (Sections 5.4, 6.4,
7.4, 8.4, 9.4 and 10.4), and the information provided regarding the
Proposed Case energy model in Section 1.4 is consistent with the Building Design.”

So in our case, would the GBCI accept a model of the baseline and proposed building with the existing envelope?

Would the GBCI accept a model of the baseline building with HVAC system type and efficiency as defined in Appendix G/section 6.4 and a model of the proposed building with the existing HVAC system type and efficiency?

Would the GBCI accept a model of the baseline building with the lighting power density as defined in 90.1-2007 section 9 and a model of the proposed building with the existing lighting power density?

We have heard of a case where the GBCI rejected the model because the envelope, which was not in the scope of work, did not meet the minimum requirements of 90.1-2007.

Thank you for your feedback.