Different results in Ideal Loads if I calculate the ventilation + infiltration load all together at the zone level than if I calculate the infiltration at the zone level and the ventilation at the system level.

asked 2023-10-07 05:33:58 -0600

jrgros
31 ●1 ●3

updated 2023-10-11 08:10:26 -0600

Different results in Ideal Loads if I calculate the ventilation + infiltration load all together at the zone level than if I calculate the infiltration at the zone level and the ventilation at the system level. What is this about? Makes sense?

Ventilation + infiltration load all together. End Use Consumption (kWh) Heating 2,139 Cooling 306

Infiltration at the zone level and the ventilation at the system level. End Use Consumption (kWh) Heating 1,739 Cooling 319

If you want, I can send you the two OSM files so you can check it yourself. We are talking about 23% more energy simply by introducing all the outside air as infiltrations. Such a difference seems strange to me.

CASE 1 SpaceInfiltrationdesignflowrate 1.26 ACH CASE 2 SpaceInfiltrationdesignflowrate 0.26 ACH DesignSpecificationOutdoorAir 1.00 ACH

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With the same building I have simulated the building by placing all the outside air in SpaceInfiltrationdesignflowrate and with openstudio it gives me this results in End Use Use Consumption (kWh) Heating 2,186 Cooling 319.

Then with the same building I have simulated the building separating the outside air in SpaceInfiltrationdesignflowrate and DesignSpecificationOutdoorAir and with openstudio it gives me this results in End Use Use Consumption (kWh) Heating 1,789 Cooling 333.

I have used OpenStudio together with the Ideal Air Loads HVAC measure.

jrgros ( 2023-10-11 08:02:30 -0600 )edit

Make sure you defined the DesignSpecification:OutdoorAir object into the Ideal Air Loads object. Check the idf file.

gianfra ( 2023-10-12 16:03:45 -0600 )edit

It is defined in the idf file. Energyplus must calculate differently when the air enters the thermal zone through infiltration than when the air enters through mechanical ventilation. The strange thing is that there is such a difference.

jrgros ( 2023-10-13 05:44:09 -0600 )edit

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Different results in Ideal Loads if I calculate the ventilation + infiltration load all together at the zone level than if I calculate the infiltration at the zone level and the ventilation at the system level.

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Different results in Ideal Loads if I calculate the ventilation + infiltration load all together at the zone level than if I calculate the infiltration at the zone level and the ventilation at the system level. edit

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Different results in Ideal Loads if I calculate the ventilation + infiltration load all together at the zone level than if I calculate the infiltration at the zone level and the ventilation at the system level.