Convert units and derive data
In XBRL, users can easily convert units when comparing sustainability reports that use different standards.
Comparison of data from different sustainability reports may require the conversion of data from one unit of measurement to another. The units of measurement used when reporting sustainability data can differ between reports due to the different sustainability standards used. For example, the unit of energy used in one report may be Gigajoules while another report uses Megawatt-hours. When analysing data from different reports, the data must be normalised to make comparison easier. The conversion of units to derive data that can be compared requires a common conversion mechanism. This ensures that the data can be trusted and is verifiable.
If the units of measurement are not converted:
- Comparison of data values using different units is complex.
- Verification of the differing values is difficult to achieve.
XBRL standard and converting units
The XBRL standard makes reliable conversion possible between two units of measurement. XBRL software tools can automatically convert the data units. Manual conversion of the data units is not necessary.
The conversion mechanism uses formulas defined in the XBRL Units Registry. XBRL International creates and maintains the XBRL Units Registry to ensure the units of measurement available are up to date and the conversion formulas are correct.
XBRL taxonomies should use the existing entries in the XBRL Units Registry. If a company needs to add a new entry, it should contact XBRL International to update the XBRL Units Registry.
Example
A data consumer creates a Business Information (BI) dashboard that compares reports of three companies.
The OutSourcery company reports their renewable and non-renewable energy usage in Megawatt-hours.
The Cloudify company reports their renewable and non-renewable energy usage as a percentage of the total energy consumption.
The Carmaker company report their renewable and non-renewable energy usage in Megawatt-hours and as a percentage of the total energy consumption.
Each taxonomy could enforce how those disclosures should be reported to make sure all use the same units. However, that would prevent some participants from reporting in the way most natural to them.
Instead, data preparers can prepare their reports in the way most natural to them. Then, the data can be unified during analysis, by calculating derived values. The data consumer converts all three disclosures to view the values as percentages. They create a dashboard comparing all three companies and the percentages of energy consumption generated from renewable sources.
Energy consumption analysis (Tableau report)
More detail
Units of measurement
To ensure that the correct units of measurement are used throughout sustainability reports, the following should be taken into consideration:
- Regulators should ensure that only the units of measurement defined in the XBRL Units Registry are used when creating the sustainability standards and taxonomies.
- Standard setters wanting to use a unit of measurement that is not defined in the XBRL Units Registry should contact XBRL International to get the unit of measurement added to the registry.
- Data preparers should use the same units of measurement in their facts as is used in the data source and in the sustainability standard. This allows data audits to be performed easily.
- Technical implementers and data consumers can find the formulas needed to convert International System of Units (SI) data, defined in the XBRL Units Registry. XBRL software tools can automatically convert between units using the registry conversion formulas.