Ivan Korolija's profile - activity

I would personally try to use a jEPlus python preprocessing function (http://www.jeplus.org/wiki/doku.php?i...). It has been implemented to help with such cases. Example within jEPlus folder 'example_8-PyPreProcess_E+v8.5' describes how to use python, eppy and jEPlus in a parametric project.

@carlobianchi89 I agree with @aaron

EnergyManagementSystem:Program, OverrideProg, !- Name

You might miss the Program name (OverrrideProg in this particular case) which is the same name as in the last line of the EnergyManagementSystem:ProgramCallingManager object.

@carlobianchi89. You have to be careful with "," and ";" at the end of lines in E+. You might miss some "," or ";" within you EMS code.

EnergyManagementSystem:Sensor, oDBT_SHD_value, oDBT_SHD, Schedule Value;

where oDBT_SHD is your Schedule:File object. You just need to define your variable as:

SET oDBT = oDBT_SHD_value

However, if I remembered correctly, there will be one timestep difference between the value from the csv file and the value in the simulation (not 100% sure about this)

Can you check node temperatures (and unmet hours) once you replace "Normal" Damper Heating Action with "Reverse" in all AirTerminal:SingleDuct:VAV:Reheat objects?

Can you check node temperatures (and unmet hours) once you replace "Normal" Damper Heating Action with "Reverse" in all AirTerminal:SingleDuct:VAV:Reheat objects?

Something very similar has been asked (and answered) here and here

If this question is related to the linked one than you need first to set the heating setpoint to 26C and an EMS control logic will be similar to the code desribred here

This is the code which should work in your case

Schedule:Constant,Cycle,OnOff,1; ! New schedule object

AvailabilityManager:Scheduled, ! Updated Availability Manager
  Packaged Rooftop Air Conditioner Availability Manager, 
  Cycle;

EnergyManagementSystem:Sensor,
  AptTemp,
  BLOCK1:ZONE1,
  Zone Mean Air Temperature;

! Don't forget to set heating setpoint to 26C
EnergyManagementSystem:Sensor,
  hSP,
  BLOCK1:ZONE1,
  Zone Thermostat Heating Setpoint Temperature;

EnergyManagementSystem:Actuator,
  AvailSCH_Overwrite,
  Cycle,
  Schedule:Constant,
  Schedule Value;

EnergyManagementSystem:ProgramCallingManager,
  Supervision,
  BeginTimestepBeforePredictor,
  HVAC_uncontolledloop_Supervision;

EnergyManagementSystem:Program,
  HVAC_uncontolledloop_Supervision,
  SET Toffset = 4,
  IF AptTemp > (hSP - 0.01), ! -0.01 due to system can maintain the zone temperature very close to the setpoint
  SET AvailSCH_Overwrite = 0,
  ELSEIF AvailSCH_Overwrite == 0 && AptTemp >= (hSP - Toffset),
  SET AvailSCH_Overwrite = 0,
  ELSE,
  SET AvailSCH_Overwrite = 1,
  ENDIF;

@JustinShultz, Solar radiation on a wall (which is automatically applied to any window on that wall) can be switched off completely by setting the 'Sun Exposure' to 'NoSun' in a BuildingSurface:Detailed object. I am not sure you can override solar radiation through EMS for an individual wall/window.

Hi Justin, You'll need to create an actuator for each surface you would like to change boundary condition. Boundary conditions can be various such as "Surface Convection Heat Transfer Coefficient", "Outdoor Air Wind Speed", etc. For example if you would like to set outdoor dry bulb temperature for a surface named "WALL" an actuator should be:

EnergyManagementSystem:Actuator,
    oDBT_wall, !- Name
    WALL, !- Actuated Component Unique Name
    Surface, !- Actuated Component Type
    Outdoor Air Drybulb Temperature; !- Actuated Component Control Type

I think DesignBuilder has EMS module (although in Beta version) link

Regarding the severe error I am not sure I can help just by seeing your code. You can switch on EMS outputs to check what your code does at each timestep.

Similar topic has been discussed here

The other approach could be to use EMS (also supported by DesignBuilder) in order to override weather parameters instead of changing a weather file. Choose environment-related actuators for outdoor dry bulb temperature and solar radiation (direct and diffuse) and change their values at the beginning of each timestep. The attached example changes direct and diffuse solar radiation to 0 and sets the outdoor dry bulb temperature to 18C.

! Weather file outdoor air dry bulb temperature
EnergyManagementSystem:Actuator,
    oDBT,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Outdoor Dry Bulb;              !- Actuated Component Control Type

! Weather file diffuse solar radiation
EnergyManagementSystem:Actuator,
    oDifSolar,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Diffuse Solar;              !- Actuated Component Control Type

! Weather file direct solar radiation
EnergyManagementSystem:Actuator,
    oDirSolar,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Direct Solar;              !- Actuated Component Control Type

! EMS program calling point
EnergyManagementSystem:ProgramCallingManager,
    OverrideWeatherData,       !- Name
    BeginTimestepBeforePredictor,  !- EnergyPlus Model Calling Point
    OverrideProg;           !- Program Name 1

!EMS program which sets selected weather parameters to 0
EnergyManagementSystem:Program,
    OverrideProg,           !- Name
    SET oDBT = 18,
    SET oDifSolar = 0,
    SET oDirSolar = 0;

I am not sure that a non-convex surface causes severe error. It raises a warning, however, L-shape is also non-convex polygon which results in warning when determining shadowing combinations (in case when there is a shading from other zone or detached shading element).

Hi Jamie and Yair,

Another approach can be to subtract the hole from the base surface by adding the coordinates of the hole in the opposite direction from the Vertex Entry Direction specified in the GlobalGeometryRules object. For example if the Vertex Entry Direction is Counterclockwise than the hole coordinates direction has to be Clockwise. However, the outer ring has to be connected to the inner ring somewhere (red line in the chart bellow). The surface with hole presented in the chart, in order to be recognized by E+, should have the following coordinates:

(0,0,Z),(4,0,Z),(4,3,Z),(0,3,Z),(0,0,Z),(1,1,Z),(1,2,Z),(3,2,Z),(3,1,Z),(1,1,Z)

This can get a bit more complex if there is more than one hole. In that case there have to be more than one connection between the inner ring and the outer ring. I found the most suitable place to connect inner ring with outer ring to be the shortest distance between coordinates of these two rings as shown in the second figure.

This should be possible when the heat exchanger is counterflow.

Have you tried to replace the boiler object with the district heating object, just to confirm that the issue is on the primary side?

Less solar gains can result in increased heating. On the other hand it should reduce cooling. However, due to decreased available daylight your internal gains from artificial lighting are increasing, affecting both heating and cooling. Former should be decreased while latter should be increased. It can be difficult to find a balance between all these phenomena. In addition to this, a building thermal mass also affects cooling and heating requirements.

The model can be further improved by replacing SetpointManager:SingleZone:Reheat with SetpointManager:SingleZone:Heating (this can be done in a text editor by changing the object name only). I would also apply min/max supply air temperature limits in this object (let's say 10C and 40C) insted of -99C and 99C. In addition to this, you can change back to Heating Design Days and reduce Heating Sizing Factor. Cheers, Ivan

However, this is not the major issue in your model. The major issue is selected Temperature Setpoint Node in Coil:Heating:Electric object. It should be node after Fan (Thermostat Control) instead of zone node (Node 1). You should also consider changing the sensor node in CoilSystem:Cooling:DX from Exit from Cooling Coil/Entry to Heating coil to Thermostat Control.

Hi Nadish, I slightly updated the code to set CC off when HC is available and vice versa. In order to get better results in your case, you should change EnergyManagementSystem:ProgramCallingManager from InsideHVACSystemIterationLoop to BeginTimestepBeforePredictor. Inside system iteration loop makes sense for longer timesteps. In your case it is less useful since your timestep is 1 minute which (I think) is also minimum system simulation timestep (someone corrects me if I am wrong).

Hi Nadish, Electric heater should be fine. DX heating coil operates as a heat pump and its performance is directly correlated to outdoor air temperature. Heat has to be taken from somewhere; in this case from the source with lower temperature. Evaporator located outside and connected to the heating coil (condensed in this case) is affected by outdoor air, no matter that you do not have outdoor air supplied to the zone. Oversizing the DX coil might help although the overall performance is driven by qvadratic and cubic curves you refer to in the heating coil object.

Hi Nadish, unlikely the EMS causes this issue. It is related to the outdoor air temperature and a heating coil capacity. In your Coil:Heating:DX:SingleSpeed object you specified -8C in the Minimum Outdoor Dry-Bulb Temperature for Compressor Operation field which means that your compressor is switched off whenever the outdoor temp is bellow this value (check xls file). However, even if you change it to -20C, the coil heating output is related to outdoor temp, as defined by curves, and the output decreases with the drop in outdoor temperature. On the other hand, the heating demand increases.

Alternative to use of EMS user-defined component, as suggested by Archmage, is to define the load on a loop's demand side with the LoadProfile:Plant object

Can you check what you specified in the "!- Minimum Limit Type" filed. If you set it to "Fixed Minimum" than it will always provide at least the minimum airflow rate. In the winter operation this leads to the OA dumper position close to the fully open (sometimes 100% open as well). However, if you change it to "ProportionalMinimum" you should always have the OA flow fraction between specified values. This operation can have implication on indoor air quality since the OA flow can be significantly reduced, particularly during heating season.

You might find useful the following output. For a detailed model evaluation it is worth changing the output frequency from 'hourly' to 'timestep'.

Output:Variable,*,Air System Outdoor Air Flow Fraction,Hourly;

I agree with Annie. This is expected behaviour of heating coil at part load operation when the coil's heat output is controlled by varying hot water flow rate. Part of the hot water is bypassed and you will have smaller than designed temperature drop in the whole plant loop. Check the temperature at inlet of the DistrictHeating system. Such a coil behaviour is caused by fixed physical parameters of the coil (in the case of simple hot water coil: UA at designed flow rate, nominal capacity, design in/out temperatures both air and water, etc.).

Hi Nadish, I'll have a look during day. Regarding the switching system on/off it is up to you and your control strategy. In some systems the source of energy can be switched off, such as heater and cooler, while the air is still circulated through the space; fan is kept on for a fresh air supply. In your case there is no fresh air requirements so you can switch off the complete system (air loop availability).

Hi Nadish, You are still have missing commas in the EMS program. Beside that I think that you are referring to wrong node. It should be the zone air temperature rather than supply air temperature. Moreover, I believe there are multiple issues with actuator's object names. Could you somehow upload your idf file here or somewhere else and post link here (you can use justpaste.it or similar free online services).

Hi Nadish. I haven't checked the EMS program logic yet since your EMS code is incomplete. There is the EnergyManagementSystem:ProgramCallingManager object missing. In your example it should look like: EnergyManagementSystem:ProgramCallingManager, Program Example, "User defined name" BeginTimestepBeforePredictor, "I think this is correct EMS calling point in your case" HVACuncontrolledloopSupervision; "EMS program name"

You haven't closed any of EMS objects with comma (lines starting with EnergyManagementSystem:...). Sensors are also incorrectly defined. The EMS definition of temperature sensor should be: EnergyManagementSystem:Sensos, Apt_NodeTemp, "This is user defined sensor name which is going to be used in EMS program" XXX, "here you should specify zone name for which you temperature value" Zone Mean Air Temperature; "I think the dry-bulb air temperature variable is this one; you can check in RDD file"

sure, I hope I'll be able to help you.

Not necessarily. MinimalShadowing doesn't take into account shadowing from exterior surfaces such as exterior walls from other zones or detached shading elements.

It will if you have shadowing from any exterior surface including overhangs and fins. MinimalShadowing takes into account only shadowing from windows and doors reveals.

District heating and cooling consumption shouldn't represent primary energy.District heating and cooling systems should be looked as ideal primary HVAC systems which operate at 100% efficiency supplying heating/cooling energy (with enough capacity) at desired temperature to fulfil requirements. The conversion factors should be applied to determine primary (source) energy and they are affected by the type of equipment used to produce heat/coolth.

in addition, RVI folder path might have spaces and characters which cause ReadVarsESO to crash. You should replace absolute paths with relative paths, at least for rvi file.