Hi Marcus et al.,

I received a question from one of our project energy modelers that I cannot answer -

Recently we have been receiving a new comment on EAp2 that states
“The HVAC equipment capacities cannot be autosized in the Proposed model.”

This comment brings up the following concerns. Our actual design documents include engineering of the building, safety factors, owner desired extra capacities, & good engineering practices for operation & functionality. If we are to put in the true design capacities (which are peak capacities plus safety factors not average operating conditions) but allow the baseline to auto calculate, we are never going to show energy savings as the baseline has none of the previously mentioned included. The baseline is bare bones and as minimal as one can get. Are we allowed to also put in the design capacities in for the baseline? For example, in past experience, the baseline requires more airflow because the equipment is a little less efficient and the envelope typically has a lower R value & better glazing than the proposed. However, if we have to hard input our design Peak airflows but allow the baseline to calculate airflows there will be skewed results. The reason I say this is that in general an interior room may require 50 CFM to meet its load. However, we know that diffusers need a minimum of 75-100 CFM for the air to actually reach the occupant and effectively cool the space. Therefore, our design would show 100 CFM and the baseline model would calculate 50 CFM. This does not seem like a fair and true comparison.

Can you offer insight and direction for how to adjust our model to address the reviewer concerns while still showing energy cost savings and reflecting our actual design conditions?