Why Half-Hourly Electricity Data Changes Your Scope 2 Carbon Footprint

HH Data: Most businesses still calculate Scope 2 emissions using annual grid-average electricity factors published by government. It’s simple, accepted — and increasingly misleading.

Using half-hourly (HH) electricity consumption matched to half-hourly grid carbon intensity tells a very different story.

Below is a summary of what happens when we do exactly that.

What the table shows (column by column)

1 – Year
Each reporting year assessed.

2 – Total Half-Hourly (HH) kWh Consumption
The total electricity consumed, aggregated from half-hourly metering data.
Note: total electricity use remains broadly consistent year-to-year.

3 – UK Government Emission Factor (kg CO₂/kWh)
The published annual UK grid average factor used in conventional location-based Scope 2 reporting.

4 – Total UK Government kg CO₂
This is the standard calculation most businesses report today:

Total kWh × annual government factor

This approach assumes every unit of electricity has the same carbon impact, regardless of when it is used.

5 – Average Half-Hourly Carbon Intensity (kg CO₂/kWh)
The simple average of actual grid carbon intensity across all half-hours in the year.

This already reflects:

• renewable availability

• fossil generation displacement

• system dynamics (wind, solar, imports, storage)

6 – Total HH Intensity kg CO₂
Calculated as:

Total kWh × average half-hourly carbon intensity

This shows what emissions should look like if timing is considered.

7 – HH Data kg CO₂ (True bottom-up result)
This is the most accurate figure:

Σ (half-hourly kWh × half-hourly carbon intensity)

It reflects when electricity was actually used, not just how much.

Minor differences between columns 6 and 7 are expected due to real demand patterns (load-weighting vs simple averages).

8 – Reduction vs UK Government Factors
This compares the half-hourly approach to the traditional method.

Result:
8% to 40% lower Scope 2 emissions Without using less electricity

What this means for businesses

This analysis shows that many businesses are over-reporting Scope 2 emissions simply because the current methodology ignores when electricity is consumed.

In reality:

• Overnight and high-renewable periods are often lower-carbon

• Electrification and EV charging can be cleaner than assumed

• Operational behaviour already matters — it’s just not visible in annual averages

Where Scope 2 accounting is heading

The direction of travel is clear.

Emerging and proposed changes to Scope 2 reporting include:

• Time-based emission factors

• Granular (hourly / half-hourly) accounting

• Better alignment with:

  • real grid conditions

  • demand flexibility

  • energy storage

  • dynamic pricing

The GHG Protocol has already acknowledged that static annual factors are a blunt instrument in increasingly renewable grids.

Future Scope 2 reporting is likely to:

• reward load shifting

• differentiate between “when” electricity is used

• support system-wide decarbonisation rather than just annual averages

The takeaway

The carbon impact of electricity is no longer just about how much you use — it’s about when you use it.

Businesses that start measuring electricity this way today will:

• understand their true Scope 2 footprint

• make better electrification decisions

• be ready for the next evolution of carbon reporting

While You Are Here…

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