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Ideal air loads (heating and cooling) much higher than other HVAC system loads!

asked 2016-09-07 08:05:11 -0500

SKG's avatar

updated 2017-05-08 15:43:38 -0500

As the name suggests, Ideal air loads, this suppose to estimate a small load when compared with HVAC systems. However, when I compare Ideal air loads with any other HVAC system the ideal load is always higher. Does any one knows why?

The figure below shows a comparison of different systems for my building.image description

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answered 2016-09-07 12:14:36 -0500

Can you specify what the y-axis is in your graph above?

The ideal air loads component, as defined in the InputOutput reference:

This component can be thought of as an ideal unit that mixes air at the zone exhaust condition with the specifed amount of outdoor air and then adds or removes heat and moisture at 100% efciency in order to produce a supply air stream at the specifed conditions. The energy required to condition the supply air is metered and reported as DistrictHeating and DistrictCooling.

I think what's going on is you are looking at energy, and the IdealAir loads system just reports the direct energy needed to heat or cool the air, i.e. COP = 1. All your other systems probably have COP > 2 for cooling.

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the y-axis is the total energy consumption, i.e lights, heating, cooling, equipment and so on. For ideal air loads it is different types of energy consumption + district cooling and district heating.

SKG's avatar SKG  ( 2016-09-07 23:42:02 -0500 )edit

Yes, if it's energy, you're seeing the COP difference as mentioned in the answer. If you set the COP=1 for the non-ideal air systems, you should see their energy use be greater than or equal to the ideal air loads case.

mdahlhausen's avatar mdahlhausen  ( 2016-09-08 10:53:39 -0500 )edit

Thank you so much! Your response perfectly relieved my doubts about simulation results!

Hailun Xie's avatar Hailun Xie  ( 2016-11-25 08:58:49 -0500 )edit

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Asked: 2016-09-07 08:05:11 -0500

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Last updated: Sep 07 '16