Energyplus design heating load and airflow is zero

asked 2019-05-01 06:09:24 -0500

Gregory gravatar image

updated 2019-05-01 07:51:54 -0500

Hi,

For my masterthesis I have to perform a simulation of a passive school building equipped with 5 AHU's for heat recovery and 4 of them have adiabatic cooling. I did manage to put the building and the HVAC components into Energyplus. For the HVAC system I used Open Studio and copy pasted into my E+ file. But I keep getting a lot of errors and can't manage it to fix them:

* Warning * Calculated design heating load for zone=CAFETARIA is zero. * ~~~ * Check Sizing:Zone and ZoneControl:Thermostat inputs. * Warning * Calculated design heating load for zone=CLASSROOMS EAST is zero. * ~~~ * Check Sizing:Zone and ZoneControl:Thermostat inputs.

... and this for all my zones,

AND

* Warning * ManageSizing: Calculated Heating Design Air Flow Rate for System=AIR LOOP HVAC 1 is zero. * ~~~ * Check Sizing:Zone and ZoneControl:Thermostat inputs. * Warning * ManageSizing: Calculated Heating Design Air Flow Rate for System=AIR LOOP HVAC 2 is zero. * ~~~ * Check Sizing:Zone and ZoneControl:Thermostat inputs. * Warning * ManageSizing: Calculated Heating Design Air Flow Rate for System=AIR LOOP HVAC 4 is zero. * ~~~ * Check Sizing:Zone and ZoneControl:Thermostat inputs.

AND

* Warning * GetAirPathData: AirLoopHVAC="AIR LOOP HVAC 1" has no Controllers. * Warning * GetAirPathData: AirLoopHVAC="AIR LOOP HVAC 2" has no Controllers. * Warning * GetAirPathData: AirLoopHVAC="AIR LOOP HVAC 3" has no Controllers. * Warning * GetAirPathData: AirLoopHVAC="AIR LOOP HVAC 4" has no Controllers. * Warning * GetAirPathData: AirLoopHVAC="AIR LOOP HVAC 5" has no Controllers.

So i did some research and tried to fix it:

  • I checked the thermostats but them seem fine to me. (link
  • Also I tried to add compact schedules for the internal gains only for the design days. link text

But then I just get additional errors:

* Warning * GetInternalHeatGains: Zone="KITCHEN" occupant density is extremely high. * ~~~ * Occupant Density=[20] person/m2.
* ~~~ * Occupant Density=[5.066E-002] m2/person. Problems in Temperature Out of Bounds may result.

... I checked these schedules, but again they look fine?

Everything I know is from the internet and some reading, so I am not that experienced with Energyplus. Could anyone that is more experienced with Energyplus take a look? Please, let me know and I will send you the IDF-files.

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Comments

The occupant warning says you have 20 people per m^2. You mentioned you checked the schedule, but what you need to do is look at is the design level of your People object. For cafeteria should be about 1 person per m^2, which is pretty high vs. the 0.05 person per m^2 for an office. Note that input may be in m^2 per person which would be the inverse of what is shown above. The schedule just applies a fractional value of the design load to use and a given time step.

It is possible that people are fully heating all of your spaces.

David Goldwasser gravatar imageDavid Goldwasser ( 2019-05-01 11:29:35 -0500 )edit

Without adding the compact schedules for the design days (Winter and Summer) there is no warning about internal load due to people. However, for my HVAC system I had a that zero heating load, so I did some research and found this article about a zero cooling load. In the comments is mentioned that the problem could be the internal loads, they may not be zero during design days. So I added additional compact schedules for the internal loads and took the highest number of occupants per zone for the design days.

Gregory gravatar imageGregory ( 2019-05-02 03:36:07 -0500 )edit

Unfortunately, I get this warnings about an outraged internal load due to people. But I cannot figure out were the problem comes from. Or is it not allowed to use a yearschedule AND a different (compact) schedule for design days?

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Gregory gravatar imageGregory ( 2019-05-02 03:36:20 -0500 )edit