Heating Energy in ASHRAE 90.1 Appx G Baseline System 4

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Good morning All.

We are modeling a two-story college classroom building in Fort Myers, Florida. Per ASHRAE 90.1-2004 App'x G, Table G3.1.1A, the baseline building is modeled using System 4, PSZ-HP. The proposed design is chilled water VAV with electric strip heat. We have completed numerous models comparing these system types previously using VisualDOE with results, as expected, showing the baseline building consuming approximately 1/3 (or slightly less) of the energy used by the proposed design. However, as modeled in eQUEST, when comparing the baseline building heating energy to the proposed design, results show the baseline building using approximately 1/63rd of the heating energy used by the proposed design. Internal loads are almost identical in both the proposed and baseline models. The outdoor air flow and humidity controls are identical in each model. Also, comparing peak design conditions in the simulation output shows the baseline building losing heat at approximately twice the rate of the proposed design. We are at a loss trying to determine why the heating energy is virtually non-existent in the baseline model.

Models are attached for reference. Any insight or assistance is greatly appreciated. Thanks in advance and kind regards,
Lawrin T. Ellis, PE

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Lawrin,

In the baseline model, you have zero outside air which is why the heating
energy is so low. You have specified that you're pulling OA from another
system, which appears to be an artifact from setting up a DOAS for the
Proposed model perhaps? Restore default on that input.

Also, when I ran the models in eQUEST the Proposed used 634,370 kWh/yr and
the Baseline used 690,870 kWh/yr, so I'm not sure where the 1/63rd of the
energy use was coming from.

Kendra Tupper, PE, LEED AP

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