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!
Update 29/07/24: In our latest release, we now ensure that an object that is linked to a dataset automatically is assigned the unit of the dataset as the property. This resolves an issue where some datasets were by default assigned the wrong property - e.g. 1kWh electricity was wrongly assigned a property of 1MJ.
We highly recommend reviewing the properties of your objects when you are close to completing your LCA.
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?
But why do you have to 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 relation 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, see the following section for more.
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 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 and 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 a zinc coating that your company applies to a steel frame. Your company has primary data on the usage of the zinc coating, expressed in mass (kilograms). However, ecoinvent - the LCI database uses surface area (m2) as the unit to denote the environmental impact of the zinc coating dataset. There is a mismatch between your primary data and the Ecoinvent dataset for zinc coating. In this case, you have two options:
Keep using your primary data unit (kg), and specify in the properties section how much surface area 1 kilogram of coating can cover (Figure 2). Figure 2 shows the properties are configured in a way, such that we tell Mobius that 1 kilogram of zinc coating can cover 2.5 square meters in surface area.
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 through attributing 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.