I remember the first time I was tempted to back a startup because its mission sounded like a tidy moral compass: the founders promised to “save the planet” with a biodegradable packaging technology. The pitch deck was glossy, the prototypes looked promising, and my instinct to support purpose-driven businesses was loud. But as a reporter trained to dig beyond rhetoric, I held my cheque. Over the years I’ve developed a practical checklist for evaluating environmental claims before investing a single pound — a method that balances skepticism with openness to genuine impact. Below I share that approach, the questions I ask, the evidence I look for, and the red flags that make me walk away.

Start with the claim: be specific

First, parse the claim carefully. “Sustainable,” “eco-friendly,” and “green” are marketing-friendly but meaningless without context. I ask: what exactly are they claiming?

  • Does the product reduce greenhouse gas emissions, avoid certain toxic chemicals, use less water, or sequester carbon?
  • Is the claim about the product, the manufacturing process, the supply chain, or the company’s operations?

    • A precise claim is easier to verify. If the founders can’t state the metric (e.g., “reduces CO2e by X kg per unit” or “uses 70% recycled feedstock”), that’s an early warning sign.

    Ask for evidence — not just promises

    Words matter far less than data. I ask for:

  • Baseline metrics and measurement methods (how was impact quantified?).
  • Third-party verifications, lab reports, or audit findings.
  • Results from pilot deployments or customer trials with measurable outcomes.

    • When a startup produces a life cycle assessment (LCA), pay attention to its scope. Is it cradle-to-gate, cradle-to-grave, or gate-to-gate? A narrow LCA can make improvements look larger than they are. If they cite reductions in carbon intensity, ask for the conversion factors and assumptions behind that number.

    Look for credible third-party validation

    Independent verification matters. Certifications and audits vary in rigor — some are meaningful, others are essentially self-declared. I favour these types of validation:

  • Recognised standards and certificates: ISO standards (e.g., ISO 14001 for environmental management), B Corp certification (for wider social and environmental performance), EU Ecolabel, or recognized carbon accounting standards.
  • Peer-reviewed studies or independent lab testing — especially for material performance, degradation, or toxicity.
  • Independent auditors and consultants who’ve assessed supply chains or emission inventories.

    • If a startup points to a “certificate,” I Google the issuing body to check its reputation. A cute badge isn’t proof of impact.

    Examine the supply chain — most impact happens upstream

    Many startups optimise one part of a product while ignoring the rest of the supply chain, which can negate any benefit. I ask founders about sourcing of raw materials, manufacturing partners, and transport emissions.

  • Who supplies the feedstock and where is it produced?
  • Are critical inputs reliant on high-impact processes (e.g., mining, monoculture crops, or long-haul shipping)?
  • Do suppliers have environmental management systems and transparent data?

    • I also look for traceability tools: batch-level tracking, supplier audits, and digital traceability platforms (e.g., provenance systems). If supply chain details are vague, assume the environmental case is weaker than advertised.

    Understand the counterfactual — what happens if the startup doesn’t exist?

    This is a favourite analytical trick of mine. Real impact is relative to what would have happened otherwise. I evaluate whether the startup:

  • replaces a high-impact incumbent technology (clear win),
  • creates a marginal improvement over a moderately sustainable alternative, or
  • depends on consumer behaviour changes that are unlikely at scale.

    • For instance, a compostable packaging solution only reduces landfill impact if consumers and municipal systems actually compost it. Without collection infrastructure, claims of circularity can be hollow.

    Assess scalability and rebound effects

    A technology that works in a lab or in small pilots may falter at scale. I probe how the environmental benefits scale with volume and whether there are rebound effects (where efficiency gains lead to increased consumption).

  • Is the technology resource-intensive when mass-produced?
  • Does scaling require rare materials or energy-intensive processes?
  • Could lower costs increase demand enough to offset environmental gains?

    • Scalability plans should include realistic timelines, supply commitments, and capex estimates. Without them, the path from prototype to impact is speculative.

    Financial and governance alignment with environmental goals

    Environmental promises must be embedded in governance. I look for concrete commitments in company documents and behaviour:

  • Are sustainability metrics tied to KPIs, executive compensation, or board oversight?
  • Does the cap table include investors focused only on growth-at-all-costs, or are there mission-aligned backers? Conflicting incentives can dilute impact promises.
  • Is there transparency in reporting — regular ESG disclosures or at least an environmental impact section in investor updates?

    • A founder-led sustainability culture helps, but institutionalising it through governance is more durable.

    Watch for greenwashing red flags

    Some common red flags I’ve learned to spot:

  • Vague or unquantified claims (“eco-friendly,” “green”) with no supporting data.
  • Overreliance on one-off offsets framed as a substitute for emissions reductions.
  • Cherry-picking impacts (e.g., claiming 90% recycled content while ignoring energy use or toxic chemicals).
  • Use of self-created badges or unverifiable “certifications.”
  • Secretive or evasive answers when you press for documents, data, or supplier names.

    • If someone avoids sharing basic evidence under the guise of “trade secrets,” that’s a legitimate concern — many environmental claims can be substantiated without exposing proprietary IP.

    Practical questions to ask founders — my go-to checklist

  • What is the specific environmental claim, stated in measurable terms?
  • How did you measure that impact, and can you share the data or methodology?
  • Do you have third-party verification or independent testing? Can I see the reports?
  • What is the lifecycle scope of your assessment (cradle-to-grave, cradle-to-gate, etc.)?
  • Who are your suppliers, and how do you ensure their environmental performance?
  • How will benefits change at scale, and what are the main barriers to scaling?
  • How are sustainability goals reflected in governance and KPIs?
  • What could cause your environmental impact to be worse than projected?

    • A small table to compare claim vs verification quickly

    Claim What to request Red flag
    “Carbon neutral product” LCA, emissions inventory, offsets used, verification body Offsets only, no emissions reduction plan
    “Biodegradable” Degradation testing reports under relevant standards (industrial vs home compost) No test details; claim only applies in lab conditions
    “Made from recycled materials” Percentage of post-consumer recycled content, supplier audits Unclear sourcing, or “recycled” means downcycled at low value

    Tools and resources I use

    Over the years I’ve compiled a set of useful resources that help verify claims:

  • Databases of certifications (e.g., B Lab for B Corp listings).
  • Access to academic papers and LCA repositories (e.g., ecoinvent).
  • Connections to independent testing labs and environmental consultancies.
  • Regulatory databases for chemicals and materials (e.g., ECHA for REACH substances).

    • If you’re an investor without in-house expertise, consider budgeting for an expert audit. Spending a few thousand pounds on due diligence can avoid backing a company whose environmental case collapses under scrutiny.

    When I invest, I want to be confident that environmental claims are rooted in measurable outcomes, credible verification, and durable governance. Protecting capital and protecting the planet aren’t mutually exclusive — but they do require more than good intentions. Ask for the data, press on the assumptions, and prioritise transparency. If founders can’t or won’t engage with those questions, I treat that as part of the investment risk.