About

Tierro was founded with a simple belief — that sustainability should lead to real outcomes.

Based in Aotearoa New Zealand, we work with businesses to make sustainability simple & credible.

tierro /ˈtɪ.ɛro/

noun

A play on tierra — the Spanish word for land, earth, and soil. The 'o' reimagined as a symbol of the planet and the cyclical nature of the natural world.

Who are tierro?

Man standing on ancient stone ruins in lush green mountains with clear blue sky overhead.

Lewis Foster

Founder & Principal

Kia ora, I'm Lewis — the founder of tierro.

I started tierro because I got tired of seeing sustainability treated as a marketing exercise with little substance. My focus is on outcomes that are realistic, measurable, and actually achieved — not just ambitious targets with no plan behind them.

My background spans qualified accountancy, GHG auditing, and sustainability consulting. That combination of financial and technical expertise shapes how I work — bringing a level of depth and credibility that's hard to find in one place.

Areas of Expertise

  • Organisation Carbon Footprints

  • Event Carbon Footprints

  • Product Carbon Footprints (ISO 14067)

  • GHG Auditing & Verification (ISO 14064)

  • Airport Carbon Accreditation (Level 5 Verifier)

  • Climate-related Disclosures (CRD)

  • Sustainability Strategy & Reporting