Atlantica Sustainable Infrastructure : 2022 DNV – Selected Environmental and H&S KPIs

Independent Limited Assurance Statement

to the Management of Atlantica Sustainable Infrastructure plc

Atlantica Sustainable Infrastructure plc ("Atlantica") commissioned DNV GL Business Assurance España S.L. ("DNV", "we", or "us") to conduct a limited assurance engagement over Selected Information presented in the 2022 Integrated Annual Report (the "Report") for the reporting year ending 31st December 2022.

Our Conclusion: based on the procedures we have performed and the evidence we have obtained, nothing has come to our attention that causes us to believe that the Selected Information is not fairly stated and has not been prepared, in all material respects, in accordance with the Criteria.

This conclusion relates only to the Selected Information, and is to be read in the context of this Independent Limited Assurance Report, in particular the inherent limitations explained overleaf

Our observations and areas for improvement will be raised in a separate report to Atlantica's Management. Selected observations are provided below. These observations do not affect our conclusion set out above.

• We found some non-material misstatements of the Selected	data by assets, it is observed that not all assets report information
Information, but these were corrected prior to publication.	in the same periods. This can lead to incidents in the data
• Data collection: Not all assets have digital and automated data	monitoring and control processes.
collection systems, which are particularly relevant for measuring	• New assets: When new assets of different technologies or
the presence of personnel as well as accounting for hours spent	processes are incorporated, we encourage the organisation to
(both in-house and external workers).	establish clearly and without delay the criteria to be applied to
• Criteria: we also encourage Atlantica to make progress in the	obtain performance indicators (e.g. water consumption or water
discharges in companies manufacturing components for CSP
standardisation of criteria to effectively classify and account for
Industry).
observed events, and to rely less on subjective criteria based on
the human factor.

• Data communication: in the current system for reporting indicator

Selected information

The scope and boundary of our work is restricted to the following Atlantica's key performance data for 2022 included on Section "Environmental Sustainability and Occupational Health and Safety" (Table Environmental and Health and Safety Key Performance Indicators) of the Report (the "Selected Information"), listed below:

• GHG Emissions (Global Reporting Initiative "GRI" Standards 305-1,305-2,305-3)
• • GHG Emissions Breakdown by Scope (Scope 1, 2 and 3) [tCO2e]
  • Emissions Rate per Unit of Energy Generated (Scope 1 & 2) [g CO2/kWh]
  • GHG Emissions Avoided [tCO2e]
• Non-GHGEmissions (GRI 305-7): Nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO) and other significant air emissions (VOC, HAP & PM) [t]
• Water: GRI 303-3 Water Withdrawal [m3], GRI 303-4 Water Discharge [m3] and GRI 303- 5 Water Consumption [m3]
• Waste: GRI 306-3 Waste Generated [t], GRI 306-4 Waste Diverted from Disposal [t] and GRI 306-5 Waste Directed to Disposal [t]. Segregated by Hazardous & Non-hazardous
• Health & Safety (based on GRI 403-9)
• • Lost Time Frequency Index (LTFI [index per million and per 200k hours]
  • Total Recordable Frequency Index (TRFI). [index per million and per 200k hours]
  • Total Recordable Deviations Index (TRDI) [index per million of hours]

To assess the Selected Information, which includes an assessment of the risk of material misstatement in the Report, we have used Atlantica's KPI Criteria (The "Criteria"), which can be found in Appendix A.

We have not performed any work, and do not express any conclusion, on any other information that may be published in the Report or on Atlantica's website for the current reporting period or for previous periods.

Our competence, independence and quality control

DNV's established policies and procedures are designed to ensure that DNV, its personnel and, where applicable, others are subject to independence requirements (including personnel of other entities of DNV) and maintain independence where required by relevant ethical requirements. This engagement work was carried out by an independent team of sustainability assurance professionals. Our multi-disciplinary team consisted of professionals with a combination of environmental and sustainability assurance experience.

Standard level of assurance

We performed a limited assurance engagement in accordance with the International Standard on Assurance Engagements (ISAE) 3000 revised - "Assurance Engagements other than Audits and Reviews of Historical Financial Information" (revised), issued by the International Auditing and Assurance Standards Board. This standard requires that we comply with ethical requirements and plan and perform the assurance engagement to obtain limited assurance.

DNV applies its own management standards and compliance policies for quality control, in accordance with ISO/IEC 17021:2015 - Conformity Assessment Requirements for bodies providing audit and certification of management systems, and accordingly maintains a comprehensive system of quality control including documented policies and procedures regarding compliance with ethical requirements, professional standards and applicable legal and regulatory requirements.

The procedures performed in a limited assurance engagement vary in nature and timing from, and are less in extent than for, a reasonable assurance engagement; and the level of assurance obtained is substantially lower than the assurance that would have been obtained had a reasonable assurance engagement been performed. We planned and performed our work to obtain the evidence we considered sufficient to provide a basis for our opinion, so that the risk of this conclusion being in error is reduced but not reduced to very low.

Basis of our conclusion

We are required to plan and perform our work in order to consider the risk of material misstatement of the Selected Information; our work included, but was not restricted to:

• Assessing the appropriateness of the Criteria for the Selected Information;
• Conducting interviews with Atlantica's management to obtain an understanding of the key processes, systems and controls in place to generate, aggregate and report the Selected Information;
• Performing limited substantive testing on a selective basis of the Selected Information to check that data had been appropriately measured, recorded, collated and reported;
• Recalculating the Selected Information using suitable conversion factors and/or other working assumptions as established by Atlantica's Criteria;
• Reviewing data at source and following this through to consolidated Group data;
• Reviewing that the evidence, measurements and their scope provided to us by Atlantica for the Selected Information is prepared in line with the Criteria; and
• Reading the Report and narrative accompanying the Selected Information within it with regard to the Criteria.

Inherent limitations

All assurance engagements are subject to inherent limitations as selective testing (sampling) may not detect errors, fraud or other irregularities. Non-financial data may be subject to greater inherent uncertainty than financial data, given the nature and methods used for calculating, estimating and determining such data. The selection of different, but acceptable, measurement techniques may result in different quantifications between different entities. Our assurance relies on the premise that the data and information provided to us by Atlantica have been provided in good faith. DNV expressly disclaims any liability or co- responsibility for any decision a person or an entity may make based on this Independent Limited Assurance Report.

Responsibilities of the Management of Atlantica and DNV

The Management of Atlantica have sole responsibility for:

• Preparing and presenting the Selected Information in accordance with the Criteria;
• Designing, implementing and maintaining effective internal controls over the information and data, resulting in the preparation of the Selected Information that is free from material misstatements;
• Measuring and reporting the Selected Information based on their established Criteria; and
• Contents and statements contained within the Report and the Criteria.

Our responsibility is to plan and perform our work to obtain limited assurance about whether the Selected Information has been prepared in accordance with the Criteria and to report to Atlantica in the form of an independent limited assurance conclusion, based on the work performed and the evidence obtained. We have not been responsible for the preparation of the Report.

DNV GL Business Assurance España S.L.

Madrid, Spain

March 02, 2023

DNV Business Assurance

DNV GL Business Assurance España S.L. is part of DNV - Business Assurance, a global provider of certification, verification, assessment and training services, helping customers to build sustainable business performance. https://www.dnv.com/assurance/sustainability-strategy/index.html

Appendix A. Atlantica's Key Performance Indicators (KPIs): Definitions and methodology

The information below has been prepared by Atlantica. It is intended to provide readers with a summary of the methodologies used by them to prepare the Selected Information.

2022 Reporting Criteria of Atlantica's Environmental and Health

and Safety KPIs

Atlantica engaged DNV GL Business Assurance España S.L. (DNV) to conduct an independent limited assurance engagement using the International Standard on Assurance Engagements (ISAE) 3000 Revised: 'Assurance Engagements Other Than Audits and Reviews of Historical Financial Information' over Selected Information presented in the 2022 Integrated Annual Report for the reporting year ending 31st December 2022.

The information included in the 2022 Integrated Annual Report related to 1) GHG emissions, (2) Non-GHG emissions, waste and water, and (3) Health and safety has been prepared in accordance with the following criteria:

1. GHG emissions:

• Reporting is based on GHG Protocol and ISO 14064.
• We have followed the operational control approach to calculate our GHG emissions data:
• • In group companies: we account for 100% of GHG emissions Scopes 1, 2 and 3.
  • In associated companies: we account for GHG emissions (i.e., "Atlantica's % equity interest * scopes 1 and 2") in scope 3.
• The base year of the GHG Emissions Inventory is 2020 because this is the reference year for the established objectives.
• The detail of each source and emission factor used is included in the Carbon Footprint Inventory Report.
• GRI 305-5 Reduction of GHG emissions: Offset and the Scope affected are indicated in the 2022 Integrated Annual Report.
• GHG Avoided Emissions Indicator:
• • This indicator takes into consideration the avoided Greenhouse Gas Emissions, in tons, due to Atlantica's renewable and high efficiency natural gas asset-based thermal and electrical production systems compared to emissions from non- renewable production systems.
  • Avoided Emissions are calculated using:
  • • The ratio of Scope 1 and 2 CO2eq emissions of all Atlantica's generation assets, calculated as the Scopes 1 and 2 GHG Emissions from generation assets/Electricity and thermal generation emissions for the period considered (Ton CO2eq/ MWh).
    • Electricity-relatedemissions factor obtained from the EPA's GHG emissions equivalency calculator (AVERT). This emission factor is periodically updated by this body (Ton CO2eq/ MWh).
    • Atlantica's electrical and thermal production for the period considered (GWh)
    • The avoided emissions are calculated as follows:

(Ratio AVERT*Production (e+t) Atlantica)- (Ratio Atlantica* Production (e+t) Atlantica).

2. Non-GHG Emissions, Waste and Water:

• Reporting is based on the Global Reporting Initiatives (GRI) best practices.
• For the Investments:
• • In group companies: we account for 100% of Non-GHG Emissions, Waste and Water KPIs.
  • In associated companies: we account for Non-GHG Emissions, Waste and Water KPIs based on Atlantica's equity interest (only if that associated company's weight in the KPI represents more than 5% of Atlantica's total Non-GHG Emissions, Waste or Water).

For further information, some considerations related to the indicators are included:

• GRI 305-6 Emissions of ozone-depleting substances (ODS): This Indicator is not reported.
• GRI 305-7 Nitrogen oxides (NOx), sulfur oxides (SOx), and other significant air emissions:
• • Our assets do not generate Persistent Organic Pollutants (POP).
  • Emissions of NOx, SO2 (Spain and Tenes only) and CO, in tons, come from the flaring of natural gas at assets. These emissions are determined by direct reading of installed continuous meters, or by calculating the Activity Data by an applied Emission Factor (Decreto 503/2004 or WebFIRE of the US EPA).
  • Volatile Organic Compounds (VOC) and Particulate Matter (PM) emissions are accounted for only at our US solar thermal assets from the emission rates established by the operating hours of the assets.
  • Hazardous Air Pollutants (HAPs): Biphenyl emissions are accounted for based on the emission rates established by the assets' operating hours as set forth in the corresponding permit.
• GRI 303 Water and Effluents:
• • The sources of water withdrawal and the destinations of dicharges are defined in the permits for each asset.
  • Water categories (freshwater or other waters) are determined by direct measurement of Total Dissolved Solids (TDS) levels or as a function of conductivity levels (µS/ cm) of water withdrawal and discharges.

• GRI 306 Waste:
• • The waste included in this indicator is that resulting from asset operation and maintenance activities, either directly or through O&M subcontractors.
  • All waste considered in this indicator is managed off-site.
  • Waste generated upstream or downstream in the value chain is not considered.
  • Related to 306-4a and 306-5a, the waste composition is provided on an aggregate basis for waste directed to and diverted from for disposal, differentiating:
  • • For Non-Hazardous Waste: between waste linked to water treatment and others.
    • For Hazardous Waste: between waste linked to the solar assets and other wastes.

3. Health and Safety

• Reporting is based on the Global Reporting Initiatives (GRI) best practices.
• For the Investments:
• • In group companies: we account for 100% of health and safety KPIs.
  • In associated companies: we account for 100% of health and safety KPIs if we have operational control of the asset.
• GRI 403-9Work-related injuries:
• • Three indicators are reported: rate of fatalities, rate of lost time injuries (high-consequencework-related injuries) and rate of recordable work-related injuries.
  • All indicators consider employees and subcontractors.
  • They are calculated on a 12-month aggregate basis.
  • They are calculated based on 1,000,000 hours worked.
• Total recordable deviations index
• • Every near-miss, unsafe act and condition reported by employees and subcontractors in all the assets are included in the indicator.
  • The indicator is calculated on a 12-month aggregate basis.
  • The indicator is calculated based on 1,000,000 hours worked.