How to keep exported osm version constant?

We have had several people installing the Grasshopper Plugins in the past months, all with the latest installer at the time, but some exported osm are in version 3.6 and some are in version 3.7. Since only the latest installers are available, is there a way to control the exported osm version so we can open each other’s files? Thanks! @mostapha

Hi @sunnydu,

The version of the OSM changes based on the version of the OpenStudio SDK that we ship with Pollination and Ladybug Tools. I can be wrong but I don’t think OpenStudio SDK supports saving an OSM with a previous version.

At the same time, I believe the OpenStudio application has a forward translator to update the older versions to the newer versions automatically.

@chriswmackey, is there something that we can do about this?

You are correct that OpenStudio does not support this.
You are also correct that old OSM files are always automatically updated to the current version upon opening them in a newer version of OpenStudio.

So the short answer is that people who have updated their version of Pollination and OpenStudio have all of the benefits with none of the drawbacks. They can open all of their old OSM files and everyone else’s while also taking advantage of all the bug fixes and features that come with the new OpenStuido.

It’s only the people using the older version of OpenStudio that have this problem of not being able to open newer OSMs. I think OpenStudio team has designed it this way so that you all have an incentive to update. But this means there’s not much that we can do about it.

If it’s not a complex model , you could try to edit the version identifier in the OSM text file. Or, if you have Admin privileges, there are ways to hack your installation of Pollination if you wanted to change the versions of OSMs that it exports. But both of these hacks can be prone to bugs and are all probably more painful to implement than just updating to the latest version of Pollination and OpenStudio.

Is there anything that we can do on our end to help all of your team update to the latest version of Pollination and OpenStudio?

1 Like

Hi Chris and Mostapha, having a constant version for everyone is important for us because 1) we can’t update our software all the time 2)we’ve seen different versions result in different results and sometimes old models will show errors when open in the new versions. I guess the best solution for now is for everyone to update to the latest version and save the installer for future use?

Hi @sunnydu ,

I have seen offices who do tight version control on the particular version of Pollination that they are using. So that’s always an option, particularly if you don’t need access to the bleeding edge of features that we’re developing now. Maybe you want to pick a version of Pollination around when we do a stable release of Ladybug Tools for Grasshopper. You can see here on the LBT forum that we generally do these releases every 6 months to keep pace with the stable releases of OpenStudio.

Also, I know that NREL cares deeply about this:

I remember the OpenStudio team showing me the gauntlet of tests that they run before they push a new stable release of OpenStudio in order to make sure that the results of common cases do not change by more than a couple percent. Last they told me, this gauntlet of tests takes over an hour to run and they assured me that the only permit significant changes to these results when it’s clear that their old assumptions in the test were really far from the reality of real buildings and HVAC equipment. For example, I remember that VRF results were allowed to change because the default curves were originally very far from reality.

Also, if you get an error that prevents you from opening an old OSM in the newer version of OpenStudio, I am sure that NREL would consider this a bug.

Long story short, if you let NREL know about these cases by opening issues on their GitHub, I am sure that they will respond:

Sometimes, NREL might do an extra minor release like 3.6.1 to address these cases and we will use those in our Pollination installers if they’re available.

1 Like