Greenfield, brownfield or selective: choosing your S/4HANA path

Every SAP S/4HANA programme starts with one decision that shapes cost, risk and value for years: how to get there. There are three broad options, and each one suits a different starting point.

1. Greenfield: a new implementation

A greenfield approach builds a new S/4HANA system and re-designs processes, usually around SAP best practice. Only selected data is migrated. It suits organisations whose current processes no longer fit the business, or whose ECC system carries years of custom code nobody wants to keep.

• Best for: re-engineering processes and adopting standard SAP
• Watch out for: larger change-management effort and a longer business design phase

2. Brownfield: a system conversion

A brownfield conversion technically converts your existing ECC system to S/4HANA, keeping configuration, custom code and history. It is usually faster and less disruptive for users, and it preserves investment in processes that already work well.

• Best for: stable processes and a need to move quickly
• Watch out for: custom code that must be remediated, and the temptation to skip simplification

3. Selective data transition

A selective approach builds a new target system and moves only chosen organisational units, processes or periods of data. It suits complex landscapes, mergers and divestments, or groups that want to consolidate several ECC systems.

• Best for: multi-system landscapes and carve-outs
• Watch out for: specialist tooling and careful data reconciliation

Five questions that decide the path

1. How well do your current processes serve the business today?
2. How much custom code do you have, and how much is still used?
3. How much historical data must remain available in the new system?
4. How much change can the organisation absorb in the next 18 months?
5. Are there mergers, divestments or consolidations on the horizon?

A structured readiness assessment answers these questions with evidence: a custom-code analysis, a data profile and stakeholder workshops. The result is a recommendation you can defend to your board, rather than a preference.