Properties in Mobius play a crucial role in ensuring the accuracy of your Life Cycle Assessment (LCA) models. Understanding what properties are, why they are important, and how to effectively use them in your models is an essential and often forgotten aspect of your LCA. This article covers the following questions:
What are properties, and why are they important?
Why check properties?
How to check and change properties?
Two use cases of changing properties.
Don't feel like reading an article? Watch a video tutorial on this subject instead!
What are properties, and why are they important?
Properties in Mobius are essential attributes associated with items (aka objects) in your Product inventory. They define the unit of measurement for each item and ensure consistency throughout your model. Checking and adjusting properties is necessary to ensure that your LCA results accurately reflect the environmental impact and are representative of your products.
Why check properties?
Sometimes datasets (e.g. ecoinvent datasets) in Mobius use different units of measurement than those in your model. In other words, the units of your item do not always automatically match the units from its associated dataset. In such cases, properties help you make conversions to ensure consistency. For example, if you're measuring electricity in kilowatt-hours (kWh) in your inventory, and the associated dataset’s unit of measurement is kilowatt-hours, the property for electricity should also be one kilowatt-hour (1 kWh), since the relationship between the two units is 1:1. Similarly, if you're measuring waste fabric in kilograms (kg) in your inventory, and the associated dataset’s unit is in kilograms, the property for the waste fabric should be one kilogram (1 kg).
This might still seem like an abstract concept. To help emphasize the importance of checking properties, we’ve outlined cases in Mobius that require specific attention.
The same attribute (e.g. mass), but on a different scale or unit.
Examples: grams (g) vs kilograms (kg), kilograms (kg) vs pounds (lbs).
You are using attributes (e.g. mass, or length) in your model that are different from the attributes used by the dataset (e.g. surface area).
Examples: mass vs volume (e.g., kg vs L), or mass vs surface area (e.g., kg vs m2).
There are different ways to address these cases to ensure the correctness of your results. We show some examples below.
Pro tip: the amount filled in the main property should always represent the amount of the dataset's unit that is equivalent to a unitary (1) amount of your own unit.
How to check and change properties?
1. Access the Product inventory: Navigate to the Product inventory of the product you are modeling.
2. Select an object: Choose the item that you want to check or adjust properties. This could be any component or material used in your product with a dataset attached to it (Figure 1).
Pro tip - Checking properties: It is best practice to check the properties of every object with a dataset attached to it. Objects that are not linked to a dataset, however, do not necessarily need a property attributed to it.
3. Navigate to properties: Once you've selected the item, locate the properties section within the lower part of its detail panel. Here, you'll find information about the unit of measurement associated with the item.
4. Check the property: Review the current property associated with the item. Ensure that the unit of measurement matches the intended unit for accurate assessment.
5. Adjust if necessary: If the property needs adjustment to match the unit used in your model or dataset, select the option to edit the property. Update the property to reflect the correct unit of measurement. Ensure that the property accurately represents the quantity of the item in your model (Figure 1).
Note - Alternative to changing properties: You can also convert the amounts and units used in your Product inventory to correspond to the units used in the respective datasets. It is up to you whether you want to edit the amounts and units in your Product inventory to match the dataset’s unit, or use the properties section to describe the relationship between your object’s unit and the dataset’s unit - both will result in the correct allocation of impact.
Figure 1: Selecting an object, checking and adjusting its properties in Mobius.
Caution - Changing properties: If there are discrepancies between the units (e.g., kilograms vs pounds; kilograms vs surface area), the relationship between the different units must be specified to ensure the right conversion is applied. Specifically, in the properties section, always fill in the amount of the dataset’s unit, that corresponds to a single amount of your object’s unit (see example 1 below).
6. Save changes: After making adjustments, save the changes to update the property for the selected item.
Two use cases of changing properties
1. Your unit differs from the dataset unit
Suppose you want to model the environmental impact of energy. Your company has primary data on the usage of natural gas, expressed in volume (m3). The dataset you want add to your model, uses net calorific value (MJ) as the unit to denote the environmental impact of the natural gas burned. There is a mismatch between your primary data and the dataset for the combustion of natural gas. In this case, you have two options:
Keep using your primary data unit (m3), and specify in the properties section how many MJ's are equivalent to 1 m3 of natural gas (Figure 2). The figure shows the properties are configured in a way, such that we tell Mobius that 1 m3 of natural gas is equivalent to 50 MJ. Check the tooltip to understand whether your conversion is correct!
Figure 2: Reconfiguring an object’s properties in Mobius.
Convert your primary data to be expressed in surface area (m2) before filling it in Mobius so that it aligns with Ecoinvent’s unit.
Conclusion: always specify how much of the ecoinvent’s unit is equivalent, or corresponds, to one single unitary amount of your object’s unit.
2. Modeling ‘positive’ impact
Sometimes you must add ‘positive’ environmental impact to your LCA. Some examples of positive impact include forms of carbon removal, modeling End-of-Life and Module D (loads & benefits beyond the system boundaries), or biogenic content in materials. One approach to model these forms of positive impact is to attribute a negative amount in the property field (Figure 3).
Figure 3: Modeling positive impact with properties in Mobius.
Video tutorial
Watch Emma explain these concepts in our tutorial:
Next steps
Understanding the importance and use of properties in Mobius ensures the accuracy of your LCA models. Remember to always check and adjust properties as needed to maintain consistency and accuracy in your assessments.
Ready to explore more features within Mobius? Check out our other help center articles for comprehensive guidance on maximizing your ecodesign potential.