Model Mechanical Ventilation with Heat Recovery (MVHR) and room zones in residential flat

Hi there,

I am building an energy model of a residential flat in GH + HB and I am currently stuck on 2 points:

  1. How can I model a Mechanical Ventilation with Heat Recovery (MVHR) system?
    Basically I want a fix air flow at outdoor air temperature entering the room with a % heat recovery.

  2. How do I assign specific zones to different rooms, e.g. kitchen, bedroom, etc.? I can only see ‘apartment’ in the Honeybee_ListZonePrograms.

Any help would be very much appreciated.

Thank you!

Antonietta

Hi @anto.ac,

  1. Are you talking about DOAS system with heat recovery? or DOAS without heating and cooling components?
  2. You can use small or large hotel as a reference for internal loads and schedules, and you can always override any settings by using your own values.

Hi Mingbo,

Thanks for this. I will use the hotel zones as a basis and then adjust the schedules and loads :wink:
Regarding the ventilation system, I don’t think the DOAS is what I am after. Basically the unit I would like to model does not have any heating or cooling coil, it’s just a fix volume fan-assisted system with heat recovery between supply and extract air flow. Something like this:
https://www.nuaire.co.uk/residential/heat-recovery-mvhr/mrxboxab-eco-lp2

I have used the natural ventilaiton component, assigned fan-assisted natural ventilation, but then I cannot specify the heat recovery… is there something I can do about this?

Thanks,
Antonietta

@anto.ac I probably would model a DOAS-ish system without heating and cooling coils, this has been suggested on Unmet: https://unmethours.com/question/12726/mechanical-ventilation-with-heat-recovery/

I quickly created an example file with MVHR system with 80% heat recovery.
Simple Model for MVHR test.gh (557.7 KB)

Please let me know if this makes sense to you.

Hi Mingbo,
That’s great, thank you! I have installed Ironbug but my components look different from yours and some disappear when I open your file. What am I doing wrong? How can I fix it, please?

@anto.ac it looks like you didn’t install the newest version.
Did you try to installed from https://github.com/MingboPeng/Ironbug/releases ?

I had installed the wrong version indeed. Thanks a lot!

Hi Mingbo,

I have added your MVHR component but it doesn’t seem to work properly. Would you be able to have a look at my model, please?

Thanks a lot,
Antonietta

Energy model_SIMPLE.gh (1.1 MB)

Hi @anto.ac
You just need to put the customized HVAC system to “ExportOpenStudio”:

You can also check same ironbug examples for general workflows on https://hydrashare.github.io/hydra/

HI @MingboPeng, related issue to this. If I use an Ideal Loads system and apply heat recovery on it, would the heat recovery be still on even in summer? is there a way to set up a summer bypass? or a profile for it?
Thank you!

Hello,

old message thread, but I will try to ask my question here to @MingboPeng :slight_smile:
I would like to have in my model a mechanical ventilation with Heat recovery (as you’ve shown, without heating and cooling coils) and a “2.PTHP | Residential” system.
I connected:

  • the “2.PTHP” to the “HBZones” input of the openstudio component;
  • the input “HBzones” of MVHR is the output of “2.PTHP” and the output of MVHR is connected to “HVAC systems” of the openstudio component.

Does this make sense to connect it that way?

Image:

Model:
MVHR_ladybug forum.gh (297.3 KB)

Thank you for your help!

Hi @mkdg,

You cannot use Honeybee’s template system with Ironbug system for the same zones, because Ironbug will remove all HVAC related settings before adding a new system to the model.

For all electric version: you can add PTHP system from Ironbug to your zones.

1 Like

Thank you @MingboPeng ! Now, I see differences in the results.
I multiplied by 10 the PTHP equipment (because I have 10 zones in my building):

My results show:

  • Cooling demand is higher for MVHR + PTHP (6 kWh/m2) than PTHP only (4 kWh/m2)
  • Heating demand decreases for MVHR + PTHP (17 kWh/m2) compared to PTHP only (29 kWh/m2)
  • Fan electricity demand is greater for MVHR +PTHP than for PTHP only.

I am not so experienced with such system, but I think that it makes sense :slight_smile: thank you!

One more question:
Where can I add the COP of the PTHP (for instance 4) with this new setup?