Forced natural ventilation - schedule shorter timestep

Hello everyone!

First of all: standing ovations for the ladybug tools team. Thanks a lot!

At the moment I´m working on simulations of prototypical climbing halls espacially regarding the control of natural and hybrid ventilation. Therefore I wanted to test a forced natural ventilation (because some climbing halls are using this at the moment) where the openable windows open with a certain time schedule. I was thinking about using the openingAreaFractionalSched from Set EP Air Flow. The problem is, that I want to open the windows for max. 1 minute and not a whole hour.

Is it somehow possible to create a schedule for every minute? Or does someone has another idea to implement this?

I tried it to Create CSV Schedule with 35040 values which didn´t work. And I found in an old honeybee primer that it was possible in the past to set a individual timestep, but now I cannot find this option.

Thanks a lot!

I have not done this but may be a fractional schedule can work?

Thanks for your input. Yes I was thinking about a fractional schedule, but my problem is that I don´t know how to apply a minutly based schedule to the openingAreaFractionalSched. I guess I have to apply it directly in the idf or something like, but then I can´t analyze some parameters that easily.

Hi guys, just a quick update on my question. I managed to implement a minutely based schedule and use it for my forced natural ventilation.

  1. I created this schedule (Schedule:Day:Interval, Schedule:Week:Daily, Schedule:Year) in openStudio because I´m not so familiar with coding and exported it as idf File. But of course you can code it directly yourself.

  2. I copied the part of the code into the userCustomEPLibrary.idf.

  3. Now I could call the schedule in Honeybee and use it as a openingAreaFractionalSched.

  4. Finally I had to set the timestep in energySimPar to 60 for a minutely based simulation. And to display the results also minutely you have to set the timestep in EPoutput to timestep.

I hope my workflow is clear. My file is quite messy, but when I cleaned it up, I could upload it later. But here is the userCustomEPLibrary file with the schedule. userCustomEPLibrary.idf (19.5 KB)


Hey @davidbriels, I’m having the same issue.
I created a Schedule containing 35040 (or 8760 multiplied by 4) to force open the window for 15 minutes every hour. I’m getting this error:

I didn’t understand point 3.
How can you use an IDF file as schedule?

Is there any other possibility to set a schedule with a shorter timestep than hourly?

Many thanks for your help!

Sorry for responding so late.
How did you create the schedule. As far as I know/remember, you cannot create a schedule with a time step less than one hour with the ladybug component. But as I mentioned in my post, you can use a idf file based schedule.

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@davidbriels, many thanks for your respond!

I’ll give it another try in the next weeks.

I just wanted to add what the recommended Honeybee workflow is for making IDF-type schedules that are at finer timesteps. All that you have to do is take the schedIDFText output from any of the schedule-making components and edit the text so that and of the !- Time values are going to a time other than something that falls on the hour (like 6:30 instead of 6:00). Then you can just write that text to the GH doc memory using the Add EP Objects component like so:

When you assign this to a HBZone, it will obey the finer timestep of your edits.

Unfortunately, EnergyPlus does not support CSV schedules that are at a finer timestep than an hour as noted in the documentation:
So hopefully the IDF-type schedules are good enough for what you need.