Scenarios: two different meanings, and what happens on import
The word “scenario” is used for two completely different things. One is an alternative project variant, as it was known from LCAbyg Desktop. The other is scenarios in a building product’s emission data, for example whether the waste is incinerated or landfilled. The two have nothing to do with each other, and only the latter is a function in LCAbyg today.
Project scenarios are not built in LCAbyg
Section titled “Project scenarios are not built in LCAbyg”In LCAbyg Desktop (LCAbyg 5, 2023) scenarios could be enabled on a project. That produced a set of tabs at the bottom of the window, one per scenario, and each scenario was a clone of the project with its own calculation assumptions: areas, calculation type, year of occupancy, building model, waste, transport and energy consumption.
That function does not exist in LCAbyg. There is no button that enables scenarios, and no tabs. The need is covered by versions: a version is an independent, complete set of data in the project, and you can have as many versions as you want.
| If you want to | In LCAbyg Desktop | In LCAbyg |
|---|---|---|
| try an alternative based on what you have | New scenario (clone) | Copy a version |
| start an alternative from scratch | Empty scenario | Create a new version |
| hold two alternatives up against each other | Switch tab | Compare two versions |
| designate the alternative that applies | The main model | Make the version the current one |
The difference worth knowing: in desktop the scenarios sat inside the same project and were switched with a tab, whereas versions are separate and are selected in the project’s version list. The end result is the same, several alternatives side by side in one project, but the route there is different.
What happens when importing an .lb5 file
Section titled “What happens when importing an .lb5 file”An .lb5 file can contain several building models, precisely the scenarios the project had in
desktop. On import the following applies:
- If the file contains several scenarios, the list Select scenarios to import is shown with all scenarios selected in advance. The scenario that was the main model in desktop is marked main model.
- Each selected scenario is created as its own version, and the version takes the scenario’s name.
- The version from the main model becomes the project’s current version. If the main model is not selected, the first imported version becomes the current one.
- If the file contains only one scenario, the list is skipped, and the file is imported as one version with the scenario’s name.
- If one scenario fails along the way, the others are imported anyway. The failed scenario leaves no empty version behind, and the error appears in the import report afterwards.
So the scenario concept itself does not carry over into LCAbyg. What does carry over is the content, translated into versions.
EPD scenarios are something else entirely
Section titled “EPD scenarios are something else entirely”In the library, a building product’s emission data can be divided into scenario groups. A group (for example “Disposal”) contains two or more scenarios (for example Incineration and Landfill), and each scenario has its own values for the modules the group covers. The group also has a weighting that must sum to 100 %, that is, how large a share of the building product is assumed to follow each scenario.
The weights on the building product are the product’s default mix. When the building product is inserted into a project, the mix is inherited and can be overridden for that particular use, without changing the building product in the library.
So this is data about a single building product, not an alternative project variant. If you are looking for the desktop version’s scenarios and come across scenario groups in the library, they are not the same thing.