Scope 2 emissions and office solar — what your sustainability report needs

Scope 2 emissions, briefly

Under the GHG Protocol — the global standard for corporate emissions accounting — every organisation’s emissions are categorised into three scopes. Scope 1 covers direct emissions from sources the organisation controls (boilers, vehicles, refrigerants). Scope 3 covers indirect emissions across the value chain (supplier emissions, employee commuting, business travel). Scope 2 covers indirect emissions from purchased energy — primarily grid electricity.

For most UK office occupiers, Scope 2 represents 60-90% of total Scope 1+2 emissions. The driver is the carbon intensity of UK grid electricity, which currently averages around 0.21 kg CO₂e per kWh under location-based methodology — meaning a typical 1 GWh-per-year office generates around 210 tonnes of Scope 2 emissions annually.

On-site solar PV is the single most material Scope 2 reduction available to most offices. Replacing grid electricity with on-site renewable generation reduces Scope 2 emissions by the kWh generated × the grid emissions factor for the relevant year.

Location-based vs market-based reporting

The GHG Protocol Scope 2 Guidance allows two methods of reporting Scope 2 emissions: location-based and market-based.

Location-based uses the average emissions intensity of the grid in the geography where the electricity is consumed. For UK consumption in 2024, this is around 0.21 kg CO₂e/kWh based on DEFRA conversion factors. Every kWh of grid electricity avoided reduces location-based Scope 2 emissions by 0.21 kg.

Market-based uses contractual instruments — REGOs (Renewable Energy Guarantees of Origin), GO certificates, PPAs, on-site generation — to claim specific emissions factors per kWh purchased. A site running on a 100% renewable tariff with full REGO coverage can claim 0 kg CO₂e/kWh under market-based, regardless of the underlying grid mix.

For on-site solar, both methods credit the generation. Location-based recognises the avoided grid kWh. Market-based recognises the on-site generation as zero-emission. The GHG Protocol requires dual reporting (both location and market-based numbers) for full disclosure.

What FTSE-tenant audits expect

We’ve delivered Scope 2 documentation packs for over 60 commercial office solar installations, including builds whose customer has a FTSE-100 tenant requiring Scope 2 disclosure under their own supplier audit. The audit expectations have converged on roughly the following package:

Location-based emissions calculation: kWh generated × DEFRA conversion factor for relevant year, with citation of the specific factor used and DEFRA publication reference.
Market-based emissions calculation: kWh generated × zero, with REGO certificate handling explanation (whether the on-site generation is REGO-certified or claimed on the basis of physical traceability).
REGO handling clarification: Whether the system claims REGO certification (rare for small-medium commercial), whether REGOs are surrendered against on-site consumption (often, for SEG-registered installs), or whether the claim is on physical traceability grounds (common where the generation is consumed entirely on-site).
Generation evidence: Annual kWh generation from the system’s monitoring software, with monthly resolution and string-level performance data on request.
SECR-ready narrative: A short paragraph suitable for inclusion in the customer’s SECR mandatory reporting block, covering the system specification, generation, and emissions impact.
CDP Climate Change response text: Pre-populated text for CDP questions C6 (emissions) and C8 (energy) related to on-site renewable generation.
SBTi alignment statement: Where the customer has SBTi-validated targets, a statement confirming the install supports the 1.5°C-aligned pathway.

What we provide

For every commercial office solar installation we deliver, the Scope 2 Disclosure Pack is included in the commissioning documentation. The pack covers all seven elements above, with annual updates available on request to reflect changing DEFRA conversion factors and updated generation data.

For customers with multi-site portfolios or particularly demanding tenant audit requirements (large FTSE-100 supplier programmes), we can also provide:

TCFD disclosure text for premium-listed UK customers
Carbon Reduction Plan PPN 06/21 input data for customers tendering for UK government contracts >£5m
Greening Government Commitments evidence for public-sector customers
B-Corp B Impact Assessment scoring inputs

The reporting work isn’t an add-on — it’s part of how we structure proposals from the outset. Customers who treat ESG reporting as a downstream consideration often find their solar install needs retrofit documentation work months after commissioning. We build it in from day one.

Request a free feasibility study including ESG documentation scoping.