Scope 2 Emissions Reporting: The Challenges Most Teams Underestimate

What are the challenges of Scope 2 emissions reporting?

Aspect	Location-Based	Market-Based
Emission factor source	Grid-average for region/country	Supplier-specific or residual mix
Reflects renewable procurement	No — uses average grid mix	Yes — via EACs, PPAs, tariffs
Year-on-year comparability	Stable — grid factors change slowly	Volatile — depends on contract renewals
Data availability	High — published by IEA, agencies	Variable — depends on supplier
GHG Protocol requirement	Mandatory	Mandatory (dual reporting)

Scope 2 emissions are often treated as the simplest category in a GHG Protocol inventory. Purchased electricity goes in, an emission factor comes out, and the number lands in a report. In practice, Scope 2 is where methodology choices, data gaps, and procurement decisions intersect in ways that catch even experienced sustainability teams off guard. The dual reporting requirement alone introduces a layer of complexity that most organisations underestimate until they are mid-way through their first assurance cycle.

If you have already worked through your Scope 1 reporting challenges, you may assume Scope 2 will be more straightforward. This article explains why that assumption rarely holds, and what to do about it.

What are Scope 2 emissions?

Scope 2 covers indirect emissions from the generation of purchased energy that the reporting organisation consumes. This includes electricity, steam, heating, and cooling. Unlike Scope 1 emissions, which arise from sources the organisation owns or controls, Scope 2 emissions occur at the power station or district heating plant — not on your premises. What makes them yours is the act of purchasing and consuming that energy.

The GHG Protocol Scope 2 Guidance (2015) established that companies must report Scope 2 using two methods: location-based and market-based. This dual requirement is the source of most of the complexity that follows.

Location-based vs market-based: why dual reporting creates confusion

The location-based method multiplies energy consumption by the average grid emission factor for the region or country where consumption occurs. It reflects the physical reality of the grid that serves your sites. The market-based method, by contrast, uses emission factors drawn from contractual instruments — supplier-specific data, energy attribute certificates (EACs), power purchase agreements (PPAs), or, where none of these exist, the residual mix factor for the relevant market.

In theory, both methods answer the same question: what are the emissions associated with your electricity use? In practice, they can tell very different stories. A company that procures renewable energy certificates may show a significant reduction under the market-based method while its location-based figure remains flat or even increases as grid factors are updated. This divergence is not an error — it reflects the difference between contractual claims and physical grid reality — but it creates awkward questions from investors, auditors, and internal stakeholders who expect one clear number.

The confusion deepens when teams must decide which figure to use for target-setting, which to feature in annual reports, and how to explain the gap between the two. Frameworks such as the CSRD and ESRS standards have their own preferences, and SBTi requires market-based for tracking progress against approved targets. Getting this wrong does not just affect one number — it cascades through every downstream disclosure.

The renewable energy procurement trap

Renewable energy procurement is the primary mechanism for reducing market-based Scope 2 emissions. But the landscape of instruments is layered and not every claim survives scrutiny.

Unbundled energy attribute certificates — such as Guarantees of Origin (GoOs) in Europe, REGOs in the UK, and I-RECs in other markets — are the most common route. They are also the most scrutinised. An unbundled certificate is purchased separately from the underlying electricity, meaning the buyer has no direct relationship with the generating asset. Critics argue that unbundled certificates do little to drive new renewable capacity. From a reporting standpoint, they are currently accepted under the GHG Protocol’s Scope 2 Guidance quality criteria, but their credibility is under increasing pressure from assurance providers, ESG rating agencies, and forthcoming updates to reporting standards.

Power purchase agreements (PPAs) — both physical and virtual — represent a stronger claim. A physical PPA delivers electricity from a specific asset to the buyer. A virtual (or financial) PPA is a contract for difference that does not deliver physical power but does generate bundled certificates. PPAs are operationally complex, require long-term commitments, and introduce financial risk, but they are increasingly viewed as the gold standard for credible renewable procurement.

Green tariffs offered by energy suppliers sit somewhere in between. Some are backed by dedicated generation assets and bundled certificates; others simply pass on unbundled certificates as part of the supply contract. The quality varies significantly, and sustainability teams need to interrogate the underlying instruments rather than relying on a supplier’s marketing claims.

The practical risk is clear: a company that reports zero market-based Scope 2 emissions on the strength of unbundled certificates may face challenges during limited or reasonable assurance engagements. Auditors will ask for certificate evidence, check retirement records, confirm temporal and geographic matching, and assess whether the instruments meet the GHG Protocol’s quality criteria. Any gap in the evidence trail can result in qualified findings or material restatements.

Multi-site and multi-country challenges

Scope 2 reporting becomes substantially harder as the number of sites and jurisdictions increases. Each country — and in some cases, each sub-national grid region — has its own grid emission factor. Organisations operating across Europe, Asia, and North America may need to source and apply dozens of different factors, each with its own update cycle, data provider, and methodology.

Grid factor sourcing is the first hurdle. The IEA publishes country-level factors, but many jurisdictions offer more granular data. Using the wrong factor — or the right factor from the wrong year — introduces errors that compound across a large portfolio. Teams must also decide whether to use generation-based or consumption-based factors, and whether to apply national or regional values where sub-national data exists.

Data collection from landlords and shared buildings is a persistent operational challenge. Many organisations lease office space in multi-tenant buildings where electricity is included in the service charge. In these cases, metered consumption data may not be available, and teams resort to estimated splits based on floor area, headcount, or contracted capacity. These estimates are acceptable when clearly disclosed, but they weaken the precision of the overall inventory and are flagged routinely during assurance.

Estimated vs metered consumption is a data quality issue that runs through the entire Scope 2 calculation. Where actual meter readings exist, the figure is defensible. Where estimates are used — whether from billing data, benchmarks, or pro-rata allocation — the uncertainty increases. Best practice is to track and disclose the proportion of Scope 2 data that is metered versus estimated, giving report users a clear picture of underlying data quality.

Year-on-year comparability issues

One of the most underappreciated challenges in Scope 2 reporting is maintaining comparability across reporting periods. Several factors can cause year-on-year fluctuations that have nothing to do with actual changes in energy consumption or operational efficiency.

Grid factor updates are the most common culprit. When a country updates its grid emission factor — reflecting changes in the national generation mix — every location-based Scope 2 figure for that country shifts, including the base year. If the reporting organisation does not restate its baseline, the trend line becomes misleading. A company might appear to have increased emissions simply because the grid factor was revised upward, even though its actual electricity consumption fell.

Contract renewals affect the market-based method. A company that held a PPA or green tariff in one year but switched to a standard grid supply the next will see its market-based figure jump — not because of any operational change, but because of a procurement decision. Conversely, signing a new renewable energy contract can collapse market-based emissions overnight. Both scenarios require clear narrative disclosure to avoid misleading readers.

Restating historical data is sometimes necessary but always uncomfortable. The GHG Protocol’s base year recalculation policy applies to Scope 2 just as it does to Scope 1, but the triggers are more frequent: acquisitions, disposals, changes in grid factors, or methodological corrections can all require restating prior years. Organisations that lack a clear base year policy — or that restate without adequate disclosure — risk undermining the credibility of their entire emissions trajectory.

What good Scope 2 reporting looks like

Strong Scope 2 reporting does not require perfection. It requires transparency, methodological consistency, and a clear evidence trail. The following checklist reflects what assurance providers and informed stakeholders expect to see:

• Dual reporting — both location-based and market-based figures presented separately, with clear labels and no conflation of the two methods.
• Emission factor disclosure — sources, vintage, and geographic scope of all grid factors and market-based instruments used, documented and version-controlled.
• Renewable energy evidence — certificate retirement records, PPA contract references, or green tariff documentation retained and audit-ready for every market-based claim.
• Data quality indicators — the proportion of consumption data that is metered vs estimated, disclosed at site level or aggregated with explanation.
• Base year policy — a written policy defining when and how the base year is restated, applied consistently and disclosed in the report.
• Narrative context — explanation of significant year-on-year changes, including whether variances are driven by activity changes, factor updates, or procurement decisions.
• Multi-site consistency — a single methodology applied uniformly across all geographies, with deviations documented where local data constraints require them.
• Alignment with frameworks — confirmation of which GHG Protocol guidance version is followed, and how the Scope 2 figures feed into CSRD, SBTi, CDP, or other disclosure commitments.

Meeting this standard consistently across reporting cycles is not trivial, particularly for organisations with large, distributed property portfolios or complex energy procurement strategies. But it is achievable with the right systems, processes, and governance in place.

How Horizon ESG simplifies Scope 2 reporting

Scope 2 reporting does not have to be a quarterly scramble of spreadsheets, landlord emails, and manually applied emission factors. Horizon ESG’s carbon reporting platform is built to handle the specific challenges outlined in this article: dual-method calculations, multi-country grid factor management, renewable energy instrument tracking, and automated base year recalculation.

The platform maintains an up-to-date library of location-based and market-based emission factors across all major jurisdictions, applies them automatically based on site location and contract data, and generates the audit trail that assurance providers require. For organisations managing Scope 2 across dozens or hundreds of sites, this replaces fragmented manual processes with a single, consistent workflow.

If your team is spending more time assembling Scope 2 data than analysing it, that is a process problem with a technology solution. Explore the carbon module or read more about best practice ESG reporting software to see how it fits into your broader reporting workflow.