What goes in category 1, and what doesn't
Category 1 is the production of everything you buy in the year: the cradle-to-gate emissions of making it, before it reaches you. For a small firm that usually means:
- materials and stock, including materials you install or resell;
- consumables: stationery, cleaning products, workwear, packaging;
- services: software, accountancy, legal, marketing, cleaning, catering, phones.
Leave out anything another category already covers, so nothing is counted twice. Our guide to the 15 Scope 3 categories has the full list.
| Purchase | Where it goes instead |
|---|---|
| Vans, computers, machinery you keep for years | Category 2, capital goods |
| Fuel, electricity and gas | Scope 1 and 2, with their supply chains in category 3 |
| Couriers and haulage you pay for | Category 4, upstream transport |
| Flights, trains, hotels | Category 6, business travel |
| Waste collections | Category 5, waste |
The four methods
The GHG Protocol's Scope 3 guidance gives four ways to calculate category 1, from most to least specific to your suppliers:
- Supplier-specific: the supplier gives you the footprint of the product you bought, for example from an environmental product declaration.
- Hybrid: the supplier's own Scope 1 and 2 figures, shared out to what you bought, plus averages for the materials they used.
- Average-data: the weight or number of items bought, multiplied by an average factor for that material or product.
- Spend-based: the money spent, multiplied by an average factor per pound for that kind of product.
You don't have to use one method for everything. The guidance expects firms to mix them, using the best data they have for each line and saying which method they used. For most small firms the practical route is to start with spend for everything, then improve the lines that matter.
A worked example
A 12-person electrical contractor's purchases for a year, net of VAT, using Defra's 2023 spend multipliers. Fuel, vans, travel and waste are already counted elsewhere.
| What was bought | Defra category | Spend (£) | kg CO2e per £ | kg CO2e |
|---|---|---|---|---|
| Cable, fittings and electrical equipment | Electrical equipment | 120,000 | 0.84 | 101,133 |
| Fixings, brackets and metal enclosures | Fabricated metal products | 15,000 | 0.57 | 8,516 |
| Plastic conduit and trunking | Rubber and plastic products | 10,000 | 0.64 | 6,437 |
| Workwear and PPE | Wearing apparel | 4,000 | 0.69 | 2,771 |
| Job management software | Software and IT services | 6,000 | 0.10 | 600 |
| Tool and access equipment hire | Equipment hire and leasing | 3,000 | 0.13 | 389 |
| Mobile phones and broadband | Telephone and internet | 4,000 | 0.09 | 379 |
| Accountant | Accountancy services | 5,000 | 0.05 | 251 |
| Total | 167,000 | 120,476 kg, or 120.48 tonnes |
One line, cable, fittings and electrical equipment, is 84% of the total, and the materials together are 96%. The software, accountant and phones barely register. That tells the firm exactly where better data would change the answer, and where it wouldn't.
Improving the biggest lines
- Ask your main supplier. Electrical wholesalers and manufacturers increasingly publish product carbon data. Even a footprint for your top ten products by spend replaces a big slice of the estimate.
- Use quantities where you have them. If your purchase records show metres of cable or numbers of units, an average factor per item is closer to reality than spend, because it doesn't move with prices.
- Leave the small lines on spend. Chasing a supplier footprint for your accountant's fees isn't worth the effort.
- Write down the method for each line, so next year's figures are calculated the same way. If you switch a big line to a better method, read our post on when to restate your baseline.
Spend-based figures rise and fall with prices as well as emissions, so a reduction target for category 1 is best tracked with quantities or supplier data for the lines that matter.
How Carbon Recycling helps
Upload a CSV of your purchase ledger and Carbon Recycling suggests a Defra multiplier for each account, leaves out what is already counted as energy, fuel or travel, and puts each line in category 1 or category 2, so you can see which purchases make up most of the total and which suppliers to ask first.