SECR Carbon Reporting: Software vs Spreadsheets in the UK

Written by Calvin Lo, Founder of Aphelios Software | August 2026 | 7 min read

If you have Googled "SECR example spreadsheet", you are in the same place most UK finance teams start. A workbook with tabs for electricity, gas and travel, some formulas, and a summary sheet is genuinely how the majority of SECR reports are first assembled. The question is not whether a spreadsheet can produce the numbers - it is what happens after the first year.

Where Spreadsheets Start to Fail

The first report is easy. Problems compound quickly:

• Factor drift - DESNZ grid factors fall every year. Last year’s file has last year’s numbers, and unless the workbook is rebuilt carefully, the wrong factor set silently lands in the new report.
• No audit trail - when the board or an auditor asks where the 12,400 kWh figure came from, the spreadsheet can only shrug. SECR requires methodology notes, and it expects evidence.
• One wrong row - a single mistyped unit (MWh instead of kWh) changes a tonne figure by 1,000×. There is no validation in a spreadsheet.
• Nobody can find the evidence - energy bills live in email, invoices in the accounts package, vehicle mileage in a separate tracker. The report and its evidence never meet.

What Dedicated Software Changes

Aphelios emissions is built around the SECR failure points above:

• Factor sets import themselves - the official DESNZ flat file is uploaded by an admin, versioned, and archived. Activities pick the correct factor for their year automatically.
• Evidence attached to the record - energy bills upload directly against the activity, so every number has a source document.
• Approvals that leave a trail - drafts are approved before they can be reported, and every change is recorded in an audit log that is impossible to fake in a workbook.
• Calculations you cannot break - total energy in kWh and CO2e in tonnes are computed from structured records, not fragile formulas.

When Should You Switch?

A reasonable rule of thumb: if this is your first report, your organisation is below 40 MWh (see our low energy user guide), or your volumes are tiny, a well-kept spreadsheet is defensible. Switch when any of these are true:

• You are reporting for a second consecutive year and must compare like-for-like
• More than one person needs to contribute data
• An auditor, lender or customer has asked how the figures were derived
• You want the energy-efficiency narrative to cite real numbers instead of vibes

The Cost Argument

The honest comparison includes money: dedicated software costs a monthly subscription, spreadsheets cost nothing. But the spreadsheet hours - rebuilding formulas, hunting bills, chasing colleagues, rechecking factors - repeat every single year. For most companies the software pays for itself by the second reporting cycle. And unlike a workbook, the report exports in the SECR structure the directors’ report expects, so final assembly takes minutes.

Software vs Spreadsheets FAQ

This guide is a planning aide, not legal advice. Confirm your reporting approach with your accountant before filing.