Sustainability Questions to Ask Suppliers

Last updated: May 24, 2026. Supplier sustainability questions are becoming more specific because companies need better value-chain data for emissions accounting, customer requests, sustainability reporting, due diligence, procurement decisions, CDP or EcoVadis responses, and responsible sourcing programs.

Short answer: the best supplier sustainability questions are specific, evidence-based, and proportionate to the supplier's role. Ask what you actually need to know, explain why you need it, request supporting evidence where material, and avoid turning every supplier conversation into a broad ESG audit.

Why supplier sustainability questions matter

Many companies now need sustainability information from suppliers because their own impacts, risks, and reporting obligations extend into the value chain. A buyer may need supplier data for Scope 3 emissions, human rights due diligence, sustainable procurement, product information, customer reporting, regulatory disclosures, or internal risk management.

This pressure does not only affect large suppliers. Smaller service providers, manufacturers, logistics partners, agencies, distributors, and outsourced operations providers can receive sustainability questions even when they are not directly covered by a mandatory reporting law.

The challenge is to ask questions that produce usable answers. A long questionnaire full of vague questions can create work without improving decisions. A focused set of questions can help the buyer understand risk, identify data gaps, and support suppliers in improving over time.

Start with the purpose of the request

Before sending a questionnaire, define the purpose. Supplier sustainability questions may support:

• supplier onboarding;
• contract renewal;
• Scope 3 greenhouse gas accounting;
• service-level or product-level emissions calculations;
• CDP, EcoVadis, or customer portal responses;
• human rights and environmental due diligence;
• renewable electricity or low-carbon procurement claims;
• sustainable sourcing programs;
• regulatory reporting; or
• supplier improvement plans.

The purpose affects the question set. A supplier needed for a low-risk office service should not receive the same level of request as a high-spend manufacturing supplier in a sensitive geography or emissions-intensive category.

Ask questions in levels

A practical supplier questionnaire can be structured in levels:

• Baseline questions: basic company information, policies, contact owner, and whether the supplier has existing sustainability data.
• Topic questions: environment, emissions, labor, human rights, ethics, procurement, and governance.
• Evidence questions: documents, calculations, certificates, audit reports, policies, or system exports that support key answers.
• Improvement questions: targets, corrective actions, planned initiatives, and annual refresh expectations.

This keeps the process proportionate. Ask every supplier enough to understand relevance and risk. Ask deeper questions only where the answer will affect reporting, procurement, risk management, or a customer-facing claim.

Environmental questions to ask suppliers

Environmental questions should connect to actual risks and data needs. Useful questions include:

• What are your main environmental impacts from operations, products, or services?
• Do you measure Scope 1 and Scope 2 greenhouse gas emissions?
• Do you measure relevant Scope 3 emissions?
• Can you provide emissions data related to the products or services supplied to us?
• What methodology, boundary, emission factors, and reporting period did you use for the emissions data?
• Do you purchase renewable electricity, and what evidence supports that claim?
• What energy-efficiency or emissions-reduction actions are underway?
• Do you have greenhouse gas reduction targets or a climate transition plan?
• How do you manage water use, wastewater, waste, packaging, and circularity?
• Are your operations linked to biodiversity, land-use, deforestation, pollution, or hazardous-material risks?

For emissions-related supplier requests, the evidence matters as much as the answer. A supplier's emissions number should ideally come with boundary, year, method, factor source, assumptions, exclusions, and supporting records. For more detail, see Keslio's guide to improving emissions data accounting.

Labor and human rights questions to ask suppliers

Labor and human rights questions should be risk-based. They may vary by sector, geography, workforce type, and position in the value chain. Useful questions include:

• What policies cover labor rights, working conditions, and human rights?
• How do you identify and manage human rights risks in your own operations?
• Do you prohibit forced labor, child labor, discrimination, harassment, and unsafe working conditions?
• How are working hours, wages, benefits, and overtime monitored?
• What health and safety systems are in place?
• Have there been serious incidents, grievances, findings, or corrective actions in the reporting period?
• Do workers have access to grievance channels?
• How do you train employees and managers on labor, safety, and human rights topics?
• Do you use subcontractors, temporary workers, migrant workers, or labor brokers, and how are they monitored?
• What evidence can you provide to support these responses?

These questions should not be treated as a box-ticking exercise. If a supplier operates in a higher-risk area, the buyer may need deeper due diligence and a corrective-action process rather than a simple yes/no response.

Ethics and governance questions to ask suppliers

Governance questions help buyers understand whether the supplier has basic controls in place. Useful questions include:

• Do you have anti-bribery, anti-corruption, conflict-of-interest, sanctions, and whistleblowing policies?
• Who is responsible for ethics and compliance?
• How are employees trained on business ethics?
• Have there been material legal, regulatory, corruption, fraud, or bribery incidents in the reporting period?
• Do you have a supplier code of conduct or equivalent expectations for your own suppliers?
• How do you assess and monitor your own high-risk suppliers or subcontractors?
• How do you protect data, confidential information, and customer information?
• What governance body reviews sustainability risks, policies, and performance?

For some suppliers, basic governance questions are enough. For others, particularly where corruption, sanctions, subcontracting, data security, or human rights risks are material, the buyer may need more detailed documentation and review.

Questions about supplier sustainability data

Companies often ask suppliers for data but do not ask how that data was prepared. That can create weak reporting later. Add questions such as:

• Who prepared the data?
• Which reporting period does it cover?
• Which sites, entities, products, or services are included?
• Was the data measured, calculated, estimated, or supplier-provided?
• What source records support the answer?
• Were any assumptions, exclusions, or limitations applied?
• Has the data been internally reviewed?
• Has any data been independently assured or verified?
• If not assured, what controls support the reliability of the data?
• Can the same data be refreshed annually?

Be careful with assurance language. Internal review, consultant support, and management approval are useful, but they are not the same as independent assurance by an appropriate assurance provider.

Questions for suppliers receiving customer requests

If you are the supplier receiving the questionnaire, the first step is to understand what the customer is really asking for. Ask internally:

• Is the customer asking for company-level data, product-level data, or service-level data?
• Is the customer asking for Scope 1, Scope 2, Scope 3, or all three?
• Do they need emissions linked to a specific contract or service?
• Are they asking for policies, evidence, portal answers, or a formal report?
• Do they ask for a consultant letter, independent assurance, or supporting documentation?
• What deadline applies?
• Which internal teams own the data?
• What assumptions and exclusions need to be explained?

For suppliers, the risk is overbuilding the response or answering the wrong question. Keslio's supplier request support is designed to interpret the customer request first, then scope the right response path.

What evidence should suppliers prepare?

Useful evidence depends on the question, but common records include:

• electricity, fuel, water, and waste records;
• greenhouse gas calculation workbooks and methodology notes;
• renewable electricity certificates, contracts, or supplier documentation;
• health and safety records;
• workforce and training data;
• human rights, labor, ethics, and anti-corruption policies;
• supplier code of conduct and procurement policies;
• audit reports, certifications, or assessment outputs where relevant;
• incident, grievance, or corrective-action records;
• board or management review records; and
• copies of customer requests and submitted responses.

For broader supplier preparation, see Keslio's guide on what suppliers should prepare for sustainability reporting.

How to make supplier questions more useful

Supplier engagement works better when buyers make the request clear and proportionate. Practical steps include:

• explain why the data is needed;
• separate mandatory answers from optional improvement questions;
• avoid asking for information that will not be used;
• provide definitions for emissions, renewable electricity, workforce, incidents, and reporting period;
• request evidence only for material answers;
• give suppliers a practical deadline;
• allow suppliers to explain data gaps and improvement plans;
• avoid using one questionnaire for every supplier risk level; and
• refresh the questions annually rather than starting from scratch.

The goal is not to punish suppliers for imperfect first-year data. The goal is to understand current performance, identify risk, improve data quality, and build a repeatable annual process.

A practical supplier sustainability question set

If you need a concise starting point, use these ten questions:

1. What sustainability topics are most relevant to the products or services you provide to us?
2. Do you measure Scope 1 and Scope 2 emissions, and can you provide the calculation boundary and year?
3. Can you provide emissions or activity data related to the products or services supplied to us?
4. What energy, emissions, waste, water, or circularity actions are underway?
5. What labor, health and safety, and human rights policies apply to your workforce?
6. Have there been material incidents, grievances, fines, or corrective actions in the reporting period?
7. What anti-bribery, anti-corruption, and ethics controls do you have?
8. How do you manage sustainability risks in your own suppliers or subcontractors?
9. What evidence supports your answers?
10. What data gaps or improvements should we expect in the next reporting cycle?

How Keslio can help

Keslio helps companies and suppliers turn sustainability questions into a practical response process. This can include designing supplier questionnaires, interpreting customer requests, preparing data checklists, calculating emissions, organizing evidence, drafting methodology notes, and preparing customer-ready responses.

For companies responding to buyer requests, see Keslio's supplier request support. For emissions data, Keslio supports GHG emissions calculations. For broader supply-chain reporting context, see Keslio's guide to supply chain reporting requirements suppliers need to know.

Need help with supplier sustainability questions?

If your team needs to ask suppliers better sustainability questions or respond to a customer questionnaire, Keslio can help clarify the request, identify the data needed, organize the evidence, and prepare a response that is specific enough to be useful without becoming a broad ESG project.