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How to change the ventilation in time?

asked 2015-11-09 17:46:31 -0500

lucho1987 gravatar image

updated 2015-11-09 20:41:02 -0500

Hello,

I am quite new in working with OpenStudion and EnergyPlus so I am not quite familiar with the software. I see that there are some measurements already developed to change the ventilation rate by a percentage, which basically adjusts the outdoor air flow per person value of each zone in the building. However this is done for the entire simulation time. I can add a fractional schedule to the Design Specification Outdoor Air Object. But I would like to create a measure that does this for me for any model. I was wondering if anyone had some suggestions on how to do this? I have seen measure already written to add and shift schedules, but as this is not a zone or space, I am not really sure how to do it.

Thank you

Luis

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answered 2015-11-10 09:16:41 -0500

updated 2015-11-10 09:52:32 -0500

The answer depends on what type of mechanical system you have. There are generally two categories, zone hvac such as ZoneHVACPackagedTerminalAirConditioner and built up central systems implemented in OpenStudio as AirLoopHVAC. In OpenStudio dynamic manipulation of the OA rates is generally not possible with zone hvac.

If you have a built up AirLoopHVAC system delivering outside air, there will be an AirLoopHVACOutdoorAirSystem as a component on the AirLoopHVAC and the oa system will have have a ControllerOutdoorAir. The oa controller can be used to turn ventilation on and off with the Maximum Fraction of Outdoor Air Schedule Name which is available through the OpenStudio API and Measure using this method. This is the typical thing to do when you want the oa damper closed at night or during unoccupied hours.

In OpenStudio, if you want the ventilation rates to vary fractionally through time you will want your DesignSpecificationOutdoorAir objects to define ventilation in terms of per person, and then enable demand controlled ventilation in the ControllerMechanicalVentilation object which is associated with the ControllerOutdoorAir.

Yes I know this is a little complicated. I'll make a follow up post to give you some ruby code to demonstrate this in Measure format. Also this post is relevant.

update Here is an example of what a Measure might do

# vent_schedule = on off schedule that you want the ventilation to follow

model.getAirLoopHVACs.each do |air_system|
  oa_system = air_system.airLoopHVACOutdoorAirSystem
  if ! oa_system.empty?
    oa_system.get.getControllerOutdoorAir.setMaximumFractionofOutdoorAirSchedule(vent_schedule)

    # If you want the system to use DCV then do this
    oa_system.get.getControllerOutdoorAir.controllerMechanicalVentilation.setDemandControlledVentilation(true)
  end
end
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Asked: 2015-11-09 17:46:31 -0500

Seen: 317 times

Last updated: Nov 10 '15