Case study: EU CSRD implementation & double materiality — a city or utility pilot and the results so far

Stadtwerke München (SWM), the municipal utility serving Munich with annual revenues exceeding EUR 9 billion and roughly 10,000 employees, became one of the first European public utilities to complete a full double materiality assessment under the Corporate Sustainability Reporting Directive (CSRD) and publish an ESRS-aligned sustainability report for fiscal year 2024. The utility's assessment identified 42 material sustainability topics across environmental, social, and governance dimensions, engaged over 600 internal and external stakeholders, and required an estimated 14,000 person-hours of effort across finance, sustainability, operations, and legal teams (SWM, 2025). As of early 2026, the report has passed limited assurance review by PricewaterhouseCoopers, and Munich's city council has adopted SWM's materiality findings as a template for mandatory sustainability disclosures across all city-owned enterprises. This case study examines how a large municipal utility navigated CSRD's double materiality requirements and what the results reveal for other utilities and public-sector entities preparing for compliance.

Why It Matters

The CSRD, which entered into force in January 2023, requires approximately 50,000 companies across the EU to report sustainability information according to the European Sustainability Reporting Standards (ESRS). Large public-interest entities began reporting for fiscal year 2024, with large companies following for fiscal year 2025 and listed SMEs for fiscal year 2026. The directive's defining innovation is the double materiality principle: companies must report both on how sustainability issues affect their financial performance (financial materiality, or the "outside-in" perspective) and on how their operations affect people and the environment (impact materiality, or the "inside-out" perspective).

For municipal utilities, the stakes are particularly high. European utilities collectively serve over 200 million customers and account for approximately 22% of EU greenhouse gas emissions through electricity generation, district heating, and gas distribution (Eurostat, 2025). Their capital expenditure plans, which run into billions of euros for grid modernization, renewable energy expansion, and heat network decarbonization, are directly shaped by investor expectations for ESRS-quality sustainability data. The European Central Bank's 2024 climate risk stress test found that 38% of European utility debt portfolios carry elevated transition risk exposure, making transparent sustainability reporting a precondition for favorable refinancing terms (ECB, 2024).

The regulatory enforcement landscape is also tightening. National competent authorities across EU member states are establishing CSRD supervision mechanisms, with Germany's Federal Financial Supervisory Authority (BaFin) and Federal Office of Justice (Bundesamt für Justiz) designated as joint enforcers. Penalties for non-compliance include fines of up to EUR 10 million or 5% of annual turnover, depending on the member state. For executives and sustainability teams at in-scope organizations, understanding how early adopters like SWM operationalized double materiality is essential for managing compliance timelines, resource allocation, and audit readiness.

Key Concepts

Understanding SWM's implementation approach requires familiarity with several technical and regulatory concepts central to CSRD reporting.

Double materiality assessment (DMA) is the foundational analytical process required by ESRS 1. It evaluates each potential sustainability topic along two independent axes: the significance of the company's actual or potential impacts on people and the environment (impact materiality), and the significance of sustainability-related risks and opportunities for the company's financial position, performance, and cash flows (financial materiality). A topic is material if it meets the threshold on either axis.

European Sustainability Reporting Standards (ESRS) comprise 12 standards: two cross-cutting standards (ESRS 1 on general requirements and ESRS 2 on general disclosures), five environmental standards (E1 through E5 covering climate, pollution, water, biodiversity, and resource use), four social standards (S1 through S4 covering own workforce, workers in the value chain, affected communities, and consumers), and one governance standard (G1 on business conduct).

Impact, risk, and opportunity (IRO) identification is the process of cataloging the specific impacts, risks, and opportunities associated with each sustainability topic across the company's own operations, upstream supply chain, and downstream value chain. SWM's IRO register contained 287 individual items across its energy generation, grid operations, water supply, and public transit divisions.

Value chain mapping under ESRS extends materiality analysis beyond the reporting entity's own operations to include upstream suppliers, downstream customers, and affected communities. For a municipal utility, this encompasses fuel suppliers, equipment manufacturers, construction contractors, residential and commercial customers, and communities near generation and transmission assets.

What's Working

SWM's pilot implementation has generated results that other utilities and public entities are using as benchmarks for their own CSRD preparations.

Structured Stakeholder Engagement Produced Actionable Materiality Rankings

SWM conducted a three-phase stakeholder engagement process between March and September 2024. Phase one involved online surveys distributed to 3,200 stakeholders across 14 categories, including employees, customers, suppliers, regulators, NGOs, academic institutions, and Munich's city council members. The response rate was 19.4%, yielding 621 completed assessments. Phase two comprised 28 structured workshops with internal subject-matter experts from each business division, using a standardized scoring rubric aligned with ESRS 1 paragraph AR16 severity and likelihood criteria. Phase three included 12 deep-dive interviews with key external stakeholders, including Bavaria's state environmental agency, Munich's climate protection officer, and representatives from three major institutional investors holding SWM's green bonds. The process identified 42 material topics out of 94 initially screened, with climate change mitigation, energy affordability, worker health and safety, and biodiversity impacts near generation facilities scoring highest on both materiality axes (SWM, 2025).

Data Infrastructure Investment Is Paying Off Beyond Compliance

SWM invested EUR 4.2 million in a dedicated CSRD data management platform built on SAP Sustainability Control Tower, integrated with its existing SAP S/4HANA ERP system. The platform automates data collection across 23 internal source systems, including emissions monitoring, HR records, procurement databases, grid operations data, and customer service platforms. While the initial investment was substantial, the system has produced benefits beyond CSRD compliance. SWM's treasury team reported that the automated sustainability data pipeline reduced the time required to compile green bond impact reports from six weeks to four days. The procurement division is using the same data infrastructure to generate supplier sustainability scorecards, which now feed into tender evaluation criteria for contracts above EUR 500,000. SWM estimates the platform will generate EUR 1.8 million in annual efficiency savings once fully operational across all reporting cycles (SWM, 2025).

Cross-Divisional Governance Reduced Siloed Reporting

SWM established a CSRD Steering Committee chaired by its Chief Financial Officer, with permanent seats for the heads of sustainability, legal, risk management, human resources, and each operational division. The committee met biweekly during the assessment phase and monthly during report preparation. This governance structure resolved a challenge common among large utilities: fragmented sustainability data ownership. Previously, environmental data sat with the operations division, social data with HR, and governance data with legal and compliance, with no single function holding end-to-end accountability. The steering committee structure created shared ownership of materiality determinations and ensured that financial and impact perspectives were evaluated simultaneously rather than sequentially.

Limited Assurance Was Achieved on First Attempt

SWM engaged PricewaterhouseCoopers to provide limited assurance on its 2024 ESRS-aligned report, passing the engagement without qualification on the first submission. Key factors included early alignment with the assurance provider on data quality expectations, pre-audit dry runs conducted in Q3 2024, and the establishment of a formal internal control framework for sustainability data mirroring the rigor of financial reporting controls. SWM's internal audit team conducted 14 sustainability data audits during the reporting period, identifying and remediating 67 data quality issues before the external assurance engagement began.

What's Not Working

Despite its relative success, SWM's implementation revealed persistent challenges that constrain efficient CSRD compliance.

Value Chain Data Remains the Weakest Link

ESRS requirements to assess materiality across the full value chain exposed significant data gaps, particularly in upstream supply chains. SWM sources natural gas from multiple intermediaries, procures grid equipment from over 400 suppliers across 22 countries, and contracts construction services from regional firms that often lack sustainability reporting capabilities. Only 34% of SWM's tier-one suppliers were able to provide Scope 3-quality emissions data in response to supplier questionnaires. For tier-two and tier-three suppliers, the figure dropped below 8%. SWM relied heavily on spend-based estimation models and industry-average emission factors for approximately 60% of its value chain impact assessments, a methodology that satisfies minimum ESRS requirements but produces materiality scores with wide uncertainty ranges.

Resource Demands Exceeded Initial Projections

SWM initially budgeted 8,000 person-hours and EUR 2.5 million for its CSRD implementation. Actual resource consumption reached 14,000 person-hours and EUR 6.8 million, including the data platform investment. The largest cost overrun was in the double materiality assessment itself, where the iterative nature of stakeholder engagement and IRO identification required three additional workshop cycles beyond the original plan. The legal review of disclosure language, particularly around forward-looking statements and transition plan commitments, consumed 2,100 hours of external legal counsel time, an expense that was not fully anticipated.

Interoperability with Existing Reporting Frameworks Creates Duplication

SWM already reported under the Global Reporting Initiative (GRI) Standards, the EU Taxonomy Regulation, and issued green bonds under ICMA principles. While ESRS was designed for interoperability with these frameworks, practical alignment proved more difficult than expected. Differences in metric definitions, reporting boundaries, and materiality thresholds between ESRS and GRI required parallel data processes for 18 overlapping topics. EU Taxonomy alignment reporting, which CSRD embeds as a mandatory disclosure, used different activity classification codes than SWM's existing taxonomy assessments, forcing a full reclassification of eligible and aligned revenues, capital expenditures, and operating expenditures.

Smaller Municipal Entities Cannot Replicate the Approach

Munich's city council has directed all city-owned enterprises to adopt SWM's materiality framework as a template. However, smaller entities such as the municipal housing company (GWG München, approximately 800 employees) and the city's convention center operator (approximately 300 employees) lack the staff, budget, and data infrastructure to conduct assessments at comparable depth. These organizations report that the minimum viable CSRD implementation still requires two to three full-time equivalent positions for 12 to 18 months, a resource commitment that strains operations in entities with total sustainability teams of one or two people.

Key Players

Established Companies

• Stadtwerke München (SWM): The pilot entity, operating as Munich's integrated municipal utility covering electricity, gas, district heating, water, and public transit with EUR 9 billion in annual revenue.
• PricewaterhouseCoopers (PwC): Provided limited assurance services for SWM's inaugural ESRS-aligned report and advisory support on data quality frameworks.
• SAP: Supplied the Sustainability Control Tower platform integrated with SWM's existing ERP infrastructure to automate CSRD data collection and reporting.
• Siemens Energy: As a major equipment supplier to SWM's generation and grid assets, participated in the value chain data exchange pilot.

Startups

• Datamaran: Provided AI-powered materiality analysis software that SWM used to benchmark its double materiality results against peer utilities and identify emerging sustainability topics from regulatory and media signals.
• Novata: Supplied ESG data management tools used by SWM's treasury team to streamline green bond impact reporting alongside CSRD disclosures.
• Ecobio Manager: Offered environmental compliance management software that SWM integrated with its CSRD platform for pollution and waste data streams.

Investors and Funders

• European Investment Bank (EIB): Holds EUR 1.2 billion in outstanding loans to SWM, with sustainability-linked covenants that reference CSRD-quality reporting as a compliance trigger.
• Munich Re: As a major institutional investor in SWM's green bonds, provided feedback during the stakeholder engagement process on financial materiality priorities.
• KfW: Provided concessional financing for SWM's district heating decarbonization program, requiring ESRS-aligned impact reporting as a condition of disbursement.

KPI Summary

KPI	Baseline (Pre-CSRD)	Current (2025)	Target (2027)
Material topics identified (DMA)	18 (GRI-based)	42 (ESRS-based)	42+ (annual refresh)
Stakeholders engaged in materiality process	85	621	800+
Supplier sustainability data coverage (tier 1)	12%	34%	70%
Person-hours for annual sustainability report	3,200	14,000 (first year)	6,000
Data quality issues remediated pre-assurance	N/A	67	<20
Green bond impact report preparation time	6 weeks	4 days	2 days
City-owned enterprises using SWM template	0	3	12

Action Checklist

• Conduct a gap analysis comparing current sustainability reporting practices against all 12 ESRS standards to identify data, process, and governance deficits at least 18 months before the first reporting deadline
• Establish a cross-functional CSRD steering committee with executive sponsorship from the CFO or CEO to ensure financial and impact materiality perspectives are integrated from the outset
• Map the full value chain including upstream suppliers, downstream customers, and affected communities to define the scope of the double materiality assessment before beginning stakeholder engagement
• Invest in dedicated sustainability data management infrastructure that integrates with existing ERP and operational systems rather than relying on spreadsheet-based data collection
• Engage external assurance providers early in the process to align on data quality expectations, internal control requirements, and the scope of limited assurance before the reporting period closes
• Budget for at least 1.5 to 2 times the initially estimated resource requirements for the first CSRD reporting cycle, accounting for iterative stakeholder engagement, legal review, and data remediation
• Develop a supplier engagement strategy that prioritizes tier-one suppliers representing the highest materiality impacts and provides standardized data request templates aligned with ESRS disclosure requirements

FAQ

Q: How long does a double materiality assessment take for a large utility? A: SWM's experience suggests 6 to 9 months for a comprehensive assessment, including stakeholder engagement, IRO identification, scoring, and validation. The timeline is heavily influenced by organizational complexity: SWM operates across five distinct business divisions (electricity, gas, district heating, water, and transit), each requiring separate IRO analyses. Simpler organizations with fewer business lines may complete the process in 4 to 5 months. The critical path is typically stakeholder engagement scheduling, as external stakeholders such as regulators, investors, and community representatives require 4 to 8 weeks of lead time for workshop participation.

Q: What does CSRD compliance cost for a first-time reporter? A: SWM's total first-year cost was EUR 6.8 million, including EUR 4.2 million for data infrastructure, EUR 1.5 million for external advisory and legal services, and EUR 1.1 million in internal labor costs above baseline. This figure reflects a large, complex organization building enterprise-grade infrastructure. Industry surveys suggest that mid-size companies (1,000 to 5,000 employees) typically spend EUR 500,000 to EUR 1.5 million in the first year, declining to EUR 200,000 to EUR 600,000 in subsequent years as processes mature and data collection is automated. The cost of external limited assurance alone ranges from EUR 80,000 to EUR 300,000 depending on organizational complexity and assurance scope.

Q: Can smaller organizations use SWM's approach as a template? A: The materiality framework and governance structure are transferable in principle, but the resource intensity must be scaled. Munich's smaller city-owned enterprises have adopted a simplified version that uses SWM's 42 material topics as a starting point and conducts a streamlined relevance screening rather than a full bottom-up DMA. This reduces the assessment timeline from 6 to 9 months to approximately 8 to 12 weeks but sacrifices granularity. The European Financial Reporting Advisory Group (EFRAG) has published implementation guidance for SMEs and smaller entities that provides additional simplification options, including the use of sector-specific materiality presumptions that reduce the number of topics requiring detailed assessment.

Q: How does the double materiality assessment differ from a traditional GRI materiality analysis? A: The key difference is the mandatory financial materiality dimension. Traditional GRI materiality assessments focused primarily on stakeholder-identified impact topics, essentially the inside-out perspective. ESRS double materiality adds a rigorous outside-in assessment: for each topic, organizations must evaluate whether sustainability-related risks and opportunities could materially affect revenues, costs, asset values, or access to capital. SWM found that 8 of its 42 material topics were material only from a financial perspective and would not have been identified through a GRI-style process alone. These included energy price volatility, regulatory transition risk, and stranded asset exposure in its natural gas distribution network.

Sources

• Stadtwerke München. (2025). ESRS-Aligned Sustainability Report: Fiscal Year 2024. Munich: SWM GmbH.
• European Central Bank. (2024). 2024 Climate Risk Stress Test: Results for Significant Institutions. Frankfurt: ECB Banking Supervision.
• Eurostat. (2025). Energy Statistics: Greenhouse Gas Emissions by Sector, EU-27. Luxembourg: Publications Office of the European Union.
• European Financial Reporting Advisory Group. (2025). ESRS Implementation Guidance: Double Materiality Assessment. Brussels: EFRAG.
• PricewaterhouseCoopers. (2025). CSRD Readiness Survey: European Utilities Sector. Frankfurt: PwC Germany.
• German Federal Ministry of Justice. (2024). CSRD Transposition Act (CSR-Richtlinie-Umsetzungsgesetz): Implementation Guidance for In-Scope Entities. Berlin: BMJ.