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OutdoorAir Schedule

asked 2019-11-04 17:03:56 -0600

BrunoRaviolo gravatar image

I'm trying to emulate a variable natural ventilation flow by assigning a OS:DesignSpecification:OutdoorAir with 5 air changes per hour with a fractional schedule to some thermal zones.

Outdoor AIr Method is set to Maximum and only the Outdoor Air Flow Air Changes per Hour field has a value greater than zero: five.

The fractional schedule is intended to reduce natural ventilation to just 1 ach during 6am-6pm and 5 ach during the night period.

However all Zone Ventilation Rates are not only higher than expected, but also show some minor fluctuations that do not correspond to what i've modeled.

What could be wrong?

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answered 2019-11-05 12:06:50 -0600

The Design Specification Outdoor Air object is intended to model mechanical ventilation. Depending on your HVAC system, the actually ventilation rate may be changed by several things including the economizer and zone diffusers if using VAV terminals.

With your approach, model ventilation rates by adjusting the infiltration rates and schedule instead. If you want to model natural ventilation at a higher level of fidelity, use the Add Wind and Stack Open Area measure on BCL.

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Asked: 2019-11-04 17:03:56 -0600

Seen: 189 times

Last updated: Nov 05