LEED CI V4 Energy Model, 2 Floors

You will need the guidance in the Reference Guide to complete these models.
Proposed
1. yes
2. Both. The Reference Guide explains how the AHUs should be modeled in your situation.
3. Usually not.
4. Proportionally.

Baseline is according the Appendix G
1. Yes
2. Yes
3. Yes
4. Yes
5. The Baseline system is based on the total building area and number of floors, not the project area/floors.

The district guidance is also in the Reference Guide. I would think that the baseline system would not change.

You clearly need the Reference Guide. There are a few options you have and the baseline depends on the option you choose. Typically they are according to Appendix G. The new DES guidance does not change the baseline system like the previous one did.

Sounds like you want Path 2. Path 1 and 3 treat the DES as purchased energy. The only difference in Path 3 is you account for an average plant efficiency in the rates.

Dear Marcus,

I've noticed you mention " The new DES guidance does not change the baseline system like the previous one did."

Need to know which version is the "new", as the latest I find is entitled "v2.2 and v2009 (guidance v2.0)" , and need to know if there's a more recent one please...

The v4 version is included within the Reference Guide.

Another related question, 
When AHU is serving the whole floor, and my tenant area is only 15% of the whole floor area, reference guide asks to adjust both AHU flow rate and fan power (to account for relative contribution), so I multiplied both by 0.15.

Actually doing this yielded very low efficient fan, that's because because fans always have curves (nothing is linear), but applying the reference guide linearized fan performance, giving very low fan efficiency in proposed case.

My question is, can I leave fan power and efficiency autosized, and just model actual contribution of the flow rate in the proposed case?
otherwise I'm not making any savings, especially my space is already small (300 m2)...

Thanks a lot

New question - the reference guide has two conflicting pieces of information (to my reading).  What am I missing?

Reference guide says, "exception - base building must use ASHRAE 90.1 sections a-e, and not Section f"

But in the reference guide table under "common issues with energy models" there is a first line that says the same, and the second line that refers to "existing building envelope" differently, that says that we can / should use the base building existing condition if it was conditioned pre-construction.  Does that mean that we CAN use the preconstruction condition (this is a 40 year old building with a poor envelope, we are adding insulation to the envelope as part of our interior fitout of the floors we're renovating).

Thx

The exclusion of "f" is right in the credit language so this would superseed anything else in the Reference Guide. So you model the ASHRAE 90.1 insulation values from Table 5.5x in the baseline no matter what the existing or pre-existing conditions are.

Personally I don't think this is how it should be. In your case if you are bringing the envelop up to better than code conditions you should get credit for it. The logic behind it, I suppose, is that if you are touching the envelop you would technically be required to bring it up to the code minimum anyway so that should be the comparative.

Thanks, Marcus!

I guess we should hope that the reference guide is changed - if that specific line in the reference guide table does not apply, it should be removed.  What purpose could it serve other than to confuse people - and in fact in this case it even confused the LEED reviewers, who later sent a clarifying email saying, 'pay no attention to the comment about the envelope.'  So at least we're in good company with our confusion!

I would agree with you - upgrading the envelope is something we recommend but there is an incentive (first cost) to leave it alone.  In my mind there should be an extra incentive to upgrade an older and poorer performing envelope - so using the existing condition as a baseline would reward people for taking on the envelopes most at need for upgrade.  Of course the owner has the operational incentive to upgrade regardless of LEED, but it should be in sync, if you ask me.  And of course I would not mind getting credit for more savings.

Thanks again for the comment.