I’m making a script for a development project investigating the relationships between embodied carbon and operational energy in MEP systems.
I’m trying to set up an MVHR system with a summer bypass in Ironbug. I can see in the ZoneERV description that an optional controller can be added to simulate the economizer operation.
I’m unsure how to do this, would you be able to provide some help on whether this is possible please? I’ve made an attempt (see screenshot), but it’s not really working.
The current version of the Ironbug doesn’t support the ZoneHVACEnergyRecoveryVentilatorController, but I have pushed a new update, and the new installer should be ready in an hour here: Releases · MingboPeng/Ironbug · GitHub
Note: you will need to install the new Ironbug separately before we release a new Pollination installer that includes this update.
Thanks for the earlier response — really appreciate it.
For context I’m modelling a typical UK residential apartment MVHR system. The intended behaviour is:
Winter: background ventilation flow rate
Summer: boosted flow rate (to help with overheating)
I want to drive this seasonal change with a fractional schedule on the ventilation flow rate.
What I’ve found so far is:
The ZoneHVAC:EnergyRecoveryVentilator doesn’t seem to accept a fractional profile for modulating airflow, so I rebuilt the system as a full AirLoop (DOAS + HX + variable-volume fan) to get schedule control.
I’m using Fan Electricity End Use as my indicator of whether the flow is actually changing.
What I tried varying is:
the Minimum / Maximum Fraction of Outdoor Air Schedule on the Outdoor Air Controller.
the Honeybee zone ventilation schedule.
Fan Energy responds correctly when I change flow per person or floor per area, so the fan curve and sizing are working, it’s specifically the schedules that aren’t working.
My questions are:
In this AirLoop-based setup, which input actually drives OA flow so that the fan responds?
I also had trouble building a seasonal schedule using an LB Analysis Period feeding into Ironbug schedule components — the schedule inputs didn’t seem to accept my values. How can I do this?
The main factor driving the OA flow is the ventilation requirement from the zones, and you saw the relationship after you changed the ventilation rate (flow per person/area).
I’d be very cautious about controlling OA flow directly in the HVAC systems, since this variable is an output of demand from the zones.
But the options you could do if you really want to control it in systems are 1) Availability Schedule, 2) MinimumAirFlowFractionSchedule. They may or may not work depending on how you set them up with other components, you just have to try and test them carefully.
I also had trouble building a seasonal schedule using an LB Analysis Period feeding into Ironbug schedule components — the schedule inputs didn’t seem to accept my values. How can I do this?
Try to apply it to the schedule of HB Ventilation component, that’s the correct way to do.
Use the “flow per person” for all year around ventilation requirements, and use “flow per zone” or “flow per area” for the extra boosted flow rate for the summer.
Set the method to “Sum”, and you can create a seasonal schedule here based on the total flow rate.
Many thanks for your help, I ended up sticking with the ZoneERV component to model the MVHR system. I added two components and turned the availability schedule on/off depending on the season and setting a maximum flow rate to model the winter/summer ventilation rate respectfully.
The HB fan component would’ve worked if I didn’t need heat recovery, but I wanted to capture that in my model. I then set a heat recovery percentage for the ‘winter’ ERV component and turned off the heat exchanger for the ‘summer’ ERV component.
