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2015-02-23 09:06:34 -0600 asked a question ideal air loads - maximum heating capacity

Hi all,

I am working at an architecture firm and getting to know the sketchup plugin and openstudio application. I have the results and parameters used for simulating an existing design from an engineering firm, they used designbuilder.

Now i am trying to achieve the same results with the sketchup plugin and openstudio software.

Because i am not sizing any HVAC installations and do not need to in the future it would be nice if i could achieve the results without any HVAC templates. (I am just calculating the net energy use per square meter so i don't need to use any HVAC).

In the engineering firm they used a simple HVAC, gave it a 100% efficiency and put it on a schedule. We can't put the ideal air loads on a schedule in the openstudio application but i achieved the same effect by putting the thermostat for heating very low during night time en very high for cooling during night time.

There is still a significant difference between designbuilder and openstudio results however and this is because there is obviously a maximum heating capacity in the standard HVAC put in in designbuilder.

The results below show the inside zone temperature and the heating energy for a couple of weeks in designbuilder (blue) and openstudio (red).

Inside temperature

image description

Heating energy

image description

I understand the ideal air loads in the openstudio application is restricted to the simple check box. I tried to fill in the following variable in the idf file before simulating: Maximum Sensible Heating Capacity But this seems to make no difference.

Does anyone of you know how to set this maximum heating capacity? Is it nog the sensible heating capacity parameter? If it is only possible to do so with a standard HVAC template where would be a good place to start reading?

2015-02-19 10:49:37 -0600 commented answer Openstudio application: ideal air loads with heat-recovery

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

2015-02-18 07:19:05 -0600 asked a question Openstudio application: ideal air loads with heat-recovery

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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2015-02-17 02:56:54 -0600 asked a question Component shading object

Hi guys,

I am trying to model the shading around the windows in the openstudio sketchup plugin. Is there a way to do this in the form of a shading component instead of a shading group? Otherwise it will be impossible to test different shading types because i would have to change this manually in the model around each window.

I tried to add a shading group in a component but the shading zones apparantly have to be added at the top level of the sketchup model.

Has anyone had the same problem and maybe found a solution?

2015-02-16 09:56:54 -0600 received badge  Student (source)
2015-02-16 08:27:00 -0600 asked a question Energyplus output parameters: Transmission/Ventilation/Solar gains/Internal gains/Infiltration

Dear all,

I succesfully built an Openstudio model using the plugin en calculated the district heating and cooling consumption in the openstudio application.

To check if these results can be trusted i am trying to visualize the different heat flows at any given hour.

I am trying, but can't seem to find the right output parameters to use for getting this information.

Hopefully someone can help me, what are the names of the output parameters i need to use to get:

  • Transmission heat gains/losses
  • Ventilation heat gains/losses
  • Solar heat gains
  • Internal heat gains
  • Infiltration heat losses

(For the entire building enveloppe, so the opaque surfaces - walls, roofs, floors - and the windows)

Thank you in advance.