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Zone Cooling Load and Coil Load

asked 2014-12-14 13:33:15 -0600

updated 2015-07-11 10:45:55 -0600

In the report from EnergyPlus, what's the difference from the HVAC Sizing Summary:Zone Cooling Load and the Cooling Coils:Coil Load ?

I thought that if I had a coil for only one zone, the COIL LOAD should be the same of the ZONE LOAD, but this isn't happening in my model with a water cooled system.

What could be the additional load in the coil besides the thermal load zone?

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@Pithon. Use energyplus and openstudio as tags, not as the header. Tags are used to index questions and to forward them to subscribers (i.e., people who are interested in those topics).

__AmirRoth__ gravatar image__AmirRoth__ ( 2014-12-14 14:03:59 -0600 )edit

Thank's Amir. I reviewed this.

Geraldo Pithon gravatar imageGeraldo Pithon ( 2014-12-14 14:56:34 -0600 )edit

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answered 2014-12-15 08:54:11 -0600

updated 2016-08-03 22:56:19 -0600

The HVAC Sizing Summary reports the zone heating and cooling loads from the sizing calculations. This is only the sensible zone load. It includes envelope, internal loads (lights, people, etc.) and infiltration, but it does not include the ventilation loads for any outdoor air which may be provided by the HVAC system.

The Equipment Summary reports the coil sizing results which is based on the supply air conditions specified in the Sizing:System object with entering conditions that include any outdoor air specified for that system. These conditions determine the design coil load (sensible and latent) which is used to size the coil. Then the nominal (or rated) capacity is also reported at standard conditions depending on the type of coil.

For DX cooling coils, these are at ARI standard conditions: air entering the cooling coil at 26.7°C dry bulb/19.4°C wet bulb (80F/67F), air entering the outdoor condenser coil at 35°C dry bulb/23.9°C wet bulb (95F/75). For chilled water cooling coils, the rated conditions are rated inlet conditions are: air entering the coil at 26.67C dry bulb/19.44C wet bulb (80F/67F), inlet chilled water temperature = 6.67C (44F). Water coils report the design coil load (total).

Note that currently the design coil load is only reported for water coils (not DX coils) and is reported as a total load. I've posted a suggestion Issue #4628 to add reporting of the design coild load used for sizing (both latent and sensible) for all coils.

Referencing the answer posted here since this is a closely related question: https://unmethours.com/question/1980/...

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Thank's Michael!!

I understood perfectly and it's very usefull.

Geraldo Pithon gravatar imageGeraldo Pithon ( 2014-12-20 14:41:48 -0600 )edit

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Asked: 2014-12-14 13:33:15 -0600

Seen: 1,602 times

Last updated: Aug 03 '16