Fractional CSO vs Sustainability Manager vs Consultant: what's right for your business?
If you're getting ESG questions from customers, banks, insurers, or your board, the hardest part is often deciding who should lead it.
Do you hire a Sustainability Manager? Bring in a consultant? Or engage a Fractional CSO to set direction and build momentum?
This guide compares the three options in plain English, so you can choose the right model for your stage, risk profile, and internal capacity.
Quick take (for time-poor CEOs)
Comparison overview
Fractional CSO (fCSO)
Best for:
CEOs needing direction + governance without full-time overhead
What you get:
Strategy, prioritisation, board-ready Plan on a Page, implementation rhythm, capability building
Risks if used alone:
If scope isn't defined, it can become 'everything ESG', needs clear priorities
Time to traction:
2–6 weeks for clarity; 90 days for a working program
Sustainability Manager (in-house)
Best for:
Businesses ready for execution with internal support
What you get:
Day-to-day coordination, internal comms, data collection, program delivery
Risks if used alone:
Can be set up to fail without executive backing, governance, and clear priorities
Time to traction:
6–16 weeks depending on onboarding and clarity
Consultant (project-based)
Best for:
Specific technical workstreams
What you get:
Defined deliverables (footprint, SBTi, disclosures, policies, audits)
Risks if used alone:
Outputs can sit in silos; limited ownership; 'reporting without change'
Time to traction:
4–12 weeks per project
How to choose (simple decision guide)
Choose a Fractional CSO if…
- You need a clear ESG direction that aligns to commercial priorities
- Your board wants confidence and a credible plan
- You have limited internal capacity and need a leader to coordinate across functions
- You want to avoid greenwashing risk by building governance and evidence
Choose a Sustainability Manager if…
- You already have a strategy and governance in place
- You need someone to run programs, collect data, and coordinate internally
- You can provide executive sponsorship and cross-functional support
Choose a Consultant if…
- You need specialist technical work (carbon accounting, climate risk, materiality)
- You have someone internally who can integrate outputs into a broader plan
- You want to fill a capability gap quickly for a defined deliverable
The model we see working best
For many mid-market organisations, the strongest path is:
Fractional CSO (90 days)
Set direction, governance, and a board-ready plan
Targeted consultants
For specialist workstreams (as needed)
Internal Sustainability Manager
Hire or upskill once priorities, cadence, and executive support are established
This sequence reduces wasted spend, avoids "ESG fatigue," and builds internal capability.
Proof points and outcomes
Clients typically come to us when they need to:
- Respond to customer/tender ESG questions with confidence
- Reduce risk and director exposure through better governance and data
- Identify cost-saving operational levers (energy, waste, procurement)
- Build internal capability so ESG becomes business-as-usual
FAQs
If you want ESG leadership that's practical, commercial, and board-ready, start with clarity.