The Question of Trust in Emissions Calculations: How the GPC Standard Guarantees Data Quality and Reliability

Data Reliability in GPC

Calculating a city's carbon footprint is not just a matter of adding and multiplying numbers. In order for the result to guide strategic decisions, it is necessary to know how reliable the data on which that result is based is. "How much can we trust this data?" is the most critical question of climate action. The GPC Standard, which enables cities to report their emissions in a global language, imposes strict rules to manage not only the calculation method but also data quality.

So how does the GPC rate the quality of data and what mechanisms does it use to manage unknown data?

The Basic Formula of Calculation and the Quality Problem

At the most basic level, emission calculation is based on a simple mathematical process: Activity Data x Emission Factor.

• Activity Data: Physical data, such as how much fuel is consumed or how much waste is produced.
• Emission Factor: A coefficient that shows how much greenhouse gas that activity emits per unit.

However, not all data is of the same quality. A net electricity consumption read from a meter cannot have the same reliability as a waste amount estimated by population. This is where GPC comes in to clarify this distinction.

Grading Data Quality: High, Medium, Low

The GPC requires cities to transparently declare the reliability of the data they use. Data is rated on three main levels:

1. (H) High Reliability: Based on city-based, directly measured real consumption data. For example, precise data from electricity meters of buildings in the city fall into this category and are the most acceptable.
2. (M) Medium Reliability: Based on partial measurements or data derived from regional statistics.
3. (L) Low Reliability: Data usually based on national averages or rough estimates.

This rating system allows cities to clearly see where they need to improve data (under the Monitoring, Evaluation and Reporting - MER system) when developing evidence-based action plans.

Managing the Unknown: "Notation Keys"

It is natural for a city to lack data, but this lack cannot be left as a "gap" in reporting. The GPC requires the use of Notation Keys to justify the lack of data or why an emission has not been calculated. This is the basis for transparency.

The most commonly used keys are:

• NE (Not Estimated): The emission source is present in the city, but could not be calculated due to lack of data.
• NO (Not Occurring): This activity or emission source does not occur at all within the city boundaries (e.g. no industrial process emissions if there is no glass production in the city).
• IE (Included Elsewhere): Emissions have been calculated but are included in another category of the report.

The Role of Technology: Reliable Reporting with CimpactPro CITY

Managing data quality, grading and using notation keys correctly is a challenging and error-prone process when done manually (Excel, etc.).

Specialized software such asCimpactPro CITY automates this process, providing a huge advantage:

• Automated Quality Control: The software manages the process from data collection to_CO2ecalculation in accordance with ISO 14064-1 and the GHG Protocol.
• Audit Ready Traceability: By recording the quality and source of the data, it guarantees "accountability" in international audits.

As a result, a credible inventory according to the GPC Standard is not just one that reports "low emissions" but one that "honestly" declares the source and quality of its data. This transparency is the greatest capital that strengthens cities' access to climate finance and their alignment with global goals.