exportToOpenStudio or runEnergyPlusSimulation


#1

Hi,

I wonder if there is any advantage in using exportToOpenStudio instead of runEnergyPlusSimulation for example in your parametric energy model example? I am asking this, because I would like to limit the list of required components for my students in few basic workflows in the beginning (and maybe also because I am not a fan of OpenStudio anymore!).

More specifically about my question, can we do the same thing with runEnergyPlusSimulation? For example I noticed that it does not give the EIO file address directly, which is probably critical to smoothly collect the iteration outputs. Do you have any suggestion how to get the EIO address from the available outputs in runEnergyPlusSimulation?

Best,
Farhang


#2

@chris will give you the comprehensive answer but meanwhile the main difference between the two components is that you can model HVAC systems with OpenStudio which is not possible with the EnergyPlus component.

If you update to the latest version of Honeybee, released last month you will get the same outputs from both components:


#3

I’m curios to know why?


#4

This is my personal opinion, but it is based on 6 years of using OpenStudio as the GUI in my EnergyPlus lecture. The OpenStudio Sketchup plugin is not getting more stable but on the contrary new bugs emerge in each update that make us waste a lot of time and lose the focus of the lectures, which should be on the actual energy simulation. And most importantly, with a few surprising and illogical problems that happens from time to time even in the basic workflow, the students lose their trust in the tool and energy simulation all together.

I give you one recent example from using the latest version. We had two doors in a common wall in a building and we had used this example for years and had managed more or less to bypass the bugs to model it. But this year, when intersecting and matching the surfaces we realized that one of the overlapping doors becomes a wall. And for your information in OpenStudio it is not possible to convert a surface to a subsurface (or other way around), and if you remove such a piece of wall the whole surface is very likely to be deleted which makes the whole model useless. So, the tool again managed to surprise us with new illogical problems. And it is funny that after wasting a long time and losing the pace of the lecture, one student realized that when he pressed Ctrl-z just after the surface matching, the wall sub-surface became the door we wanted, without undoing other changes done by the command. This was also ironic, because based on experiences of the last years I had a don’t-do list for use of OpenStudio plugin which included “not pressing Ctrl-z when using OpenStudio functionalities”!

In general, the reason why I am giving up using OpenStudio is that we cannot avoid such problems even by asking the students to make like 10 step by step OpenStudio and SketchUp files (here), so that after each crashing bug they can go back one or more steps. Later in our program when they want to model more complex buildings in other courses or for their master thesis, they go through a lot of troubles to make the model geometry, which gives them the wrong impression that making the geometry is the main part of developing an energy model. I understand that one should have limited expectations from a freely available tool, but with all the issues that we have in the community to make real use of BPS tools in design and operation of buildings, wasting this much energy and time on the tools’ bugs (for just making the geometry of energy models) is a pity.

On the OpenStudio application I cannot be very accurate as we decided to use the good stable IDF Editor after the geometry creation (a workflow which by the way still suffers from using OpenStudio plugin, for example by not having easily understandable and editable compact schedules or not having generic names for constructions based on the type of surfaces). What I sensed about the application was that it still could not do everything you needed for a simple model, and again you were trapped in interface complexities and deficiencies. For example having a drag and drop functionality for adding constructions may look “sexy”, but I prefer a more stable and comprehensive procedure, which at least gives me the possibilities I have in IDF Editor.


#5

Thank you for the comprehensive reply. I don’t use the SketchUp plugin for editing or creating geometries so I was not aware of these issues. OpenStudio SketchUp plugin is no more funded and the issues that you mentioned most likely won’t get fixed. They are now working on a 2D editor for OpenStudio. If you want to keep using SketchUp and alternative is Euclid which is actually the OpenStudio legacy plugin. It’s simpler and only generates idf files instead of osm. Big Ladder is supporting the development and I assume they will fix bugs if you report them.

In any case, after reading your thoughts here, if you decided to use Honeybee for your class be aware of this issue with OpenStudio. We haven’t seen the issue to happen for OpenStudio 2.3 but it was an issue before for some users. It is one of those issues that we (Ladybug Tools developers) can’t do much about it. The issue is related to OpenStudio C# bindings and dependencies. OpenStudio team has helped us a number of times to figure out the source of the problem and we believe it was because of dependencies and is solved but you never know!

If your use of Honeybee will mostly be only creating the geometry and you won’t set up the HVAC systems then EnergyPlus component will be the safe choice. I also should say that going forward with Honeybee[+] we most likely only support OpenStudio route but that will only happen when we ensure the PINVOKE issue is gone and users won’t face unexpected bugs.


#6

@mostapha If there is no longer support for Openstudio by DOE does that mean honeybee will be changing paths as well? meaning will honeybee still be producing OSMs or is there a plan to go directly to IDF (with HVAC capabilities)


#7

DOE still supports OpenStudio development. There is no support for the SketchUp plugin but the code base, the SDK and the App are still under development and will get funding. As I mentioned they are developing a new 2D web-based interface for OpenStudio. Since we use the SDK the changes for the SketchUp plugin doesn’t affect our workflow.


#8

Sorry for being late to the discussion. As @mostapha said, there are virtually no differences between the output of the OpenStudio component and the EnergyPlus component except that the OpenStudio component can model fully-detailed HVAC systems and the EP component can only do ideal air systems.

We’ve done some validations to ensure that the results of the two components match within rounding errors.

I personally prefer not to use the sketchup interface for OpenStudio and I can’t see myself ever using it since. However, the standalone OpenStudio desktop application has been a godsend for my understanding of HVAC systems. If it were not for OpenStudio’s SDK and all of the measures shared on the building components library, there’s no way that I would have arrived to as good of an understanding of HVAC systems as I have today.

Moreover I couldn’t possibly imagine building a fully-detailed HVAC in the IDF Editor. Even writing a script to add an HVAC system in the E+ component is a daunting task. So I’d recommend using OpenStudio primarily to edit HVAC systems or build custom systems from scratch.