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Openstudio application: ideal air loads with heat-recovery

asked 2015-02-18 07:19:05 -0600

updated 2015-07-12 18:11:52 -0600

Hi all,

In the thermal zones list in the openstudio application you can just check a box choosing the ideal air loads calculation method. I use this in the early design stage to estimate the total net energy the building will use for heating/cooling. When i look in the idf file that is exported from openstudio i see this object:

HVACTemplate:Zone:IdealLoadsAirSystem,
  2C0179 Thermal Zone,                    !- Zone Name
  ,                                       !- Template Thermostat Name
  ,                                       !- System Availability Schedule Name
  ,                                       !- Maximum Heating Supply Air Temperature {C}
  ,                                       !- Minimum Cooling Supply Air Temperature {C}
  ,                                       !- Maximum Heating Supply Air Humidity Ratio {kgWater/kgDryAir}
  ,                                       !- Minimum Cooling Supply Air Humidity Ratio {kgWater/kgDryAir}
  ,                                       !- Heating Limit
  ,                                       !- Maximum Heating Air Flow Rate {m3/s}
  ,                                       !- Maximum Sensible Heating Capacity {W}
  ,                                       !- Cooling Limit
  ,                                       !- Maximum Cooling Air Flow Rate {m3/s}
  ,                                       !- Maximum Total Cooling Capacity {W}
  ,                                       !- Heating Availability Schedule Name
  ,                                       !- Cooling Availability Schedule Name
  ,                                       !- Dehumidification Control Type
  ,                                       !- Cooling Sensible Heat Ratio {dimensionless}
  ,                                       !- Dehumidification Setpoint {percent}
  ,                                       !- Humidification Control Type
  ,                                       !- Humidification Setpoint {percent}
  ,                                       !- Outdoor Air Method
  ,                                       !- Outdoor Air Flow Rate per Person {m3/s}
  ,                                       !- Outdoor Air Flow Rate per Zone Floor Area {m3/s-m2}
  ,                                       !- Outdoor Air Flow Rate per Zone {m3/s}
  ,                                       !- Design Specification Outdoor Air Object Name
  ;                                       !- Demand Controlled Ventilation Type

Is there any way in openstudio to give more details about the ideal air loads system? Can you specify heat recuperation in the ventilation in the openstudio app?

I now have a different object in the idf-file as following:

ZoneVentilation:DesignFlowRate,
  2C0179 Thermal Zone Ventilation per Person, !- Name
  2C0179 Thermal Zone,                    !- Zone or ZoneList Name
  Medium Office Bldg Occ 4,               !- Schedule Name
  Flow/Person,                            !- Design Flow Rate Calculation Method
  ,                                       !- Design Flow Rate {m3/s}
  ,                                       !- Flow Rate per Zone Floor Area {m3/s-m2}
  0.00611111,                             !- Flow Rate per Person {m3/s-person}
  ,                                       !- Air Changes per Hour {1/hr}
  ,                                       !- Ventilation Type
  ,                                       !- Fan Pressure Rise {Pa}
  ,                                       !- Fan Total Efficiency
  ,                                       !- Constant Term Coefficient
  ,                                       !- Temperature Term Coefficient
  ,                                       !- Velocity Term Coefficient
  ;                                       !- Velocity Squared Term Coefficient

This now handles the ventilation. Is it correct to assume that all the heat from ventilation is lost with this setup with the two objects: HVACTemplate:Zone:IdealLoadsAirSystem and Zoneventilation:Designflowrate? Because for now i have just used the output parameters

Output:Variable,*,Zone Ventilation Total Heat Loss Energy,monthly; !- HVAC Sum [J]
Output:Variable,*,Zone Ventilation Total Heat Gain Energy,monthly; !- HVAC Sum [J]

to report the heat losses through ventilation and subtracted 70% of these from the district heating consumption.

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answered 2015-02-19 08:25:17 -0600

I don't think I can answer all of your questions, but I can definitively tell you that ideal air loads in OpenStudio is limited to the simple checkbox. If you need more advanced inputs we encourage you to use one of the system templates and configure the details as you need.

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Thank you, main question was if ideal air loads was limited to the simple checkbox. I'll start digging into the HVAC system templates

bo@ar-te gravatar image bo@ar-te  ( 2015-02-19 10:49:37 -0600 )edit

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Asked: 2015-02-18 07:19:05 -0600

Seen: 866 times

Last updated: Feb 19 '15