Activity-based vs spend-based

There are two main ways to measure emissions:

• Activity-based data – based on what physically happened
• Spend-based data – based on how much money you spent

Both are valid. The key is knowing when to use which, and how they show up in your Salvidia assessments.

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The basic difference

Activity-based
Uses real-world quantities (kWh, litres, km, tonnes, etc.)

Spend-based
Uses money spent (e.g. AUD, NZD, USD) as a proxy for emissions

Examples:

• Activity-based:
  • 12,500 kWh of electricity
  • 3,200 litres of diesel
  • 4.2 tonnes of mixed landfill waste
• Spend-based:
  • $120,000 on marketing services
  • $45,000 on IT and software
  • $9,500 on catering

In both cases, Salvidia uses emission factors to convert the input into CO₂e, but activity-based data is generally closer to reality.

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At a glance

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Activity-based data

Activity-based data uses physical quantities directly linked to emissions. Common examples:

• kWh of electricity
• Litres of petrol, diesel, gas
• Kilometres travelled by mode and vehicle type
• Tonnes of waste by stream (landfill, recycling, organics)
• Tonnes or kg of materials and products

Why it’s preferred:

• Less influenced by price changes, inflation, or exchange rates
• Easier to compare across time and locations
• More useful for designing reduction projects (“use less fuel / different materials”, not just “spend less”)

In Salvidia, most Energy, Travel, Waste, and Product tables are designed for activity-based inputs.

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Spend-based data

Spend-based methods use money spent as a proxy for emissions. Example:

• $10,000 spent on IT services
• × emission factor per dollar (kg CO₂e / $)
• = emissions estimate for that spend

Spend-based data is useful when:

• You don’t have detailed activity data
• You’re dealing with lots of small purchases
• You want a first-pass footprint using finance exports

It’s most common for:

• Professional services
• Marketing and advertising
• Office supplies
• Software and subscriptions
• “Long tail” vendors where activity data isn’t realistic to collect

In Salvidia, spend-based methods are usually used in Purchases and services tables, where categories and factors can be mapped to your spend.

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Pros and cons

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When to use which

A simple rule of thumb:

• Use activity-based when:
  • You have metered or measurable data (kWh, litres, tonnes, km, etc.)
  • The category is material (big part of your footprint)
  • You’re planning reduction actions in that area
• Use spend-based when:
  • Activity data is unavailable or extremely hard to get
  • You want to cover many small, diverse purchases
  • You’re doing an initial screening or rough baseline

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Examples

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Electricity (office or event venue)

• Best: kWh from meter readings or bills (activity-based)
• Avoid: spend-based factors for electricity if you can easily get kWh

In Salvidia:
Add to Energy and utilities with kWh, not just $.

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Business travel

• Flights:
  • Better: distance and class per flight (activity-based)
  • Fallback: total spend on flights by region/route (spend-based)
• Hotels and accommodation:
  • Activity-based if you have nights by city and hotel type
  • Spend-based if you only have total $ from finance

In Salvidia:
Use the Travel and transport tables. Aim for activity-based where booking data is available.

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Purchased services (e.g. marketing, legal, IT)

• Often no practical activity metric
• Spend-based is usually appropriate
• You can still improve quality over time by:
  • Better categorisation
  • Supplier-specific data where available

In Salvidia:
Use Purchases and services, mapped to appropriate spend-based factors.

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Waste

• Best: tonnes per stream (landfill, recycling, organics, etc.) from waste contractors
• Fallback: spend on waste services by stream (spend-based)

In Salvidia:
Use Waste and materials with tonne-based inputs if possible.

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How Salvidia handles both approaches

In Salvidia:

• Some tables are activity-first (e.g. Energy, Travel, Waste)
• Others are flexible and can support activity or spend (e.g. Purchases and services)

Under the hood, Salvidia:

1. Detects whether a row is activity-based or spend-based.
2. Applies the appropriate emission factor type.
3. Stores both the input and the method used, so you can see where your numbers came from.

This means you can:

• Start with more spend-based data in early years.
• Gradually shift important categories towards activity-based as your data improves.

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Common patterns for a first footprint

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Practical guidance for your assessments

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If you only remember three things

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Where to go next

• Learn about Data quality tiers (if enabled)
• See how this sits inside Carbon accounting in 10 minutes
• Or start applying it in practice in your actual data tables in Salvidia.