I overlooked the demand control requirement for the baseline system in the energy model, and have been directed by the reviewer to install it in 3 rooms based on calculation numbers, which makes sense. The proposed system does not include DCV, it hasn't been modeled, and hasn't been required by the reviewer.

The problem is that when I include the DCV into 2 of the systems that require this, the ventilation rate increase dramatically. One system goes from 34% outside air to 63% outside air requirement. The other system goes from 33% outside air to 100% outside air. The third system is part of the first floor System 5, and has been broken out to be it's own System 3 (per ASHRAE 90.1-2007 G3.1.1(b)), and the ventilation required matches the proposed exactly. The two systems with the increase in OA are a Gym and Auxiliary Gym, so separate system 3 was created in conjunction with the baseline required system 5 as described in G3.1.1(b).

My question is: is it common to include demand control ventilation into the system energy model and have such a drastic increase in ventilation air requirement? I am using Trane TRACE, so I don't know if this is a failure of the calculations, failure of the inputs, or if this difference is common. For general knowledge, the OA required to the spaces required are set to the same values and not set to be calculated, yet that seems to be what TRACE is doing.

I've always been under the impression that the ventilation between baseline and proposed should be the same, but this change has resulted in the baseline have a total building increase of 22.3% more OA then the proposed system, and the difference in the cost efficiency is about 9%.