Existing Fenestration in baseline model for CI projects

Yes you can do that. Essentially you then model the building envelop the same in both models.

Our project is a commercial retail space with 8,000 sf gross floor area and is a part of large building (~250,000 SF). The base building envelope has following features:

• Brick walls without insulation
• Single pane windows
• Window-Wall Ratio – 58%

The retail store windows will be upgraded with double pane while keeping WWR same as before. When opting for option 1: Tenant level Energy Simulation approach for EAp2, can we use existing building condition for both walls and windows with 58% WWR in baseline model as per LI-10454? Additionally, can we take credit for window upgrades in proposed case energy model?

Thanks in advance.

Vipul, that sounds right to me per ASHRAE 90.1-2010 Appendix G Table G3.1.5f) 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". 

Table G3.1.5(f) is an exception in the credit language, so you cannot model the existing conditions relative to the envelop in the baseline. The baseline is according to Appendix G.

Thanks Marcus for clarification!!

Can we still use WWR same (58%) in both baseline and proposed case?

I believe the way LI-10454 is written, CI projects can model baseline envelope using exception f of Table G3.1.5 with modified prerequisite and points requirement.  

Marcus,

Original question on this thread from Arvindraj and Vipul's last question looks very similar. Is there a specific situation/reason in Vipul's case which will not allow him to model baseline with exception f as per LI-10454? Based on your reply on original post from Arvindraj, it seems CI projects can use exception f for baseline model as per LI-10454. 

Thanks

Thanks for pointing out the conflict. The interpretation clearly allows comparison to existing conditions. The credit language clearly does not allow the use of existing conditions. My understanding is that the credit language takes precedence but perhaps that has changed. In the past credit language could not be changed except by ballot but again maybe that has changed too. Perhaps the point threshold adjustments are the rationale for allowing such a change to the credit language.

There is a difference between the two examples. In the first example there is no claim of savings, in the second there are savings claimed. In my opinion the project should be able to claim savings for replacing the windows while using the same WWR in the existing conditions. This certainly makes the most sense.