How to evaluate decarbonization solutions against your company's MACC curve

Why a “list of initiatives” never becomes a portfolio (and how the MACC helps)

In a large company, there are almost always more decarbonization ideas than capacity to execute them.

Without prioritization criteria, the portfolio turns into:

• scattered initiatives
• low comparability
• difficulty defending the budget

The MACC curve (Marginal Abatement Cost Curve) helps turn “ideas” into a prioritized portfolio, comparing initiatives by marginal abatement cost and reduction potential.

If your priority is defending the investment in decision-making language, start with the pillar article: How to defend ROI in commuting (Scope 3.7) with cycle-by-cycle evidence.

What the MACC curve is (explained at the right level)

The MACC organizes initiatives along a curve that generally considers:

• abatement potential (how much the initiative can reduce)
• marginal cost (how much it costs to reduce each unit)

In practice, to use a MACC well you do not need to start out perfect. You need to start out comparable.

How to evaluate decarbonization solutions with a MACC (step by step)

1) List the candidate initiatives (without filtering too much)

Include initiatives of different kinds:

• efficiency
• behavior change
• logistics / mobility
• energy

2) Define a comparison standard

Choose a unit and a time horizon.

The point here is not to nail “the final number” in the first cycle. It is to be able to compare initiatives using the same yardstick.

3) Estimate total cost and operating cost

Separate:

• implementation (setup)
• operation (maintenance / communication / management)

4) Estimate the reduction potential (with recorded assumptions)

For initiatives tied to Scope 3, record your assumptions and keep them consistent from cycle to cycle.

If your scope of measurement includes commuting (Category 3.7), this guide will help you avoid stalling: Scope 3 (Category 3.7): what to measure and how to get started without stalling.

5) Add a layer that a “pure” MACC does not capture: executability and evidence

Two initiatives can have similar cost and potential, but differ in:

• coordination effort (how many areas are involved)
• time to run the first cycle
• quality of the evidence

In a large company, that changes everything.

Where commuting initiatives fit on the MACC

Programs tied to daily commuting (often discussed as Scope 3.7) can be attractive when they combine:

• execution in cycles
• scalable engagement
• traceable evidence

What usually sinks these programs is not that they “don’t make sense” — it is starting without a scope of measurement, without a baseline and without a method.

Questions that separate a “good idea” from a “good decision”

Use this checklist:

• Does this have a clear owner?
• Can I run a first cycle in 30–90 days?
• Does the method generate defensible evidence?
• Can I compare across sites and improve cycle by cycle?
• Can the team operate it without it becoming a never-ending project?

FAQ (SEO)

What is a MACC curve (Marginal Abatement Cost Curve)?

It is a way of ranking reduction initiatives by marginal cost and abatement potential, helping you prioritize the portfolio.

How do I use a MACC to prioritize Scope 3 initiatives?

Define a comparable yardstick, record the assumptions behind the method, and add executability and evidence criteria on top of cost and potential.

Is a MACC enough to justify an investment (ROI)?

It works as a prioritization foundation. To defend ROI with cycle-by-cycle evidence, connect it to a management and tracking model.

Read also (this series)

• Proving ROI in commuting (Scope 3.7) with a baseline and a method (pillar)
• How companies cut costs with ESG-linked variable pay
• Scope 3 (Category 3.7): what to measure and how to get started without stalling

Next step

If you want to prioritize your portfolio (MACC-style) and walk away with an executable plan to run cycles with evidence and ROI, the next step is a quick assessment.

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