The Annex comprises four Subtasks (A–D): developing a framework for energy-efficient air cleaning (A), integrating and controlling technologies (B), addressing resilience and health-focused applications (C), and demonstrating, standardizing, and disseminating solutions (D) to support EPBD implementation in sustainable, resilient buildings.
Subtask A: Framework for Energy-Efficient Air Cleaning
Background
The transition toward sustainable and energy-efficient buildings under the Energy Performance of Buildings Directive (EPBD) requires integrating air cleaning technologies that maintain high indoor air quality (IAQ) while minimizing energy use. However, current design and assessment practices are fragmented, lacking standardized methods to evaluate the energy and air quality performance of different air cleaning systems. This subtask addresses the need for a harmonized framework that defines metrics, models, and procedures for evaluating energy-efficient air cleaning technologies and their interaction with ventilation systems across various building types and climates.
Purpose
Subtask A will establish the scientific and methodological foundation for evaluating and optimizing air cleaning technologies. It aims to develop standardized performance indicators, such as Clean Air Delivery Rate per kilowatt-hour (CADR/kWh), and create modelling tools that support EPBD implementation and performance-based building design. For emerging or additive air cleaning technologies—such as photocatalysis, plasma, and ionisation—the Annex will include evaluations under realistic indoor environmental conditions (temperature, relative humidity, VOC composition, etc.) to assess both performance and potential by-product formation resulting from indoor chemical reactions.
Strategy and Activity Structure
Subtask A consists of three main Activities aimed at developing a comprehensive performance assessment framework:
A.1 Performance metrics and indicators: Define standardized energy and IAQ performance metrics (e.g., CADR/kWh) for evaluating air cleaning systems in different operational contexts.
A.2 Modelling and energy balance: Develop simplified and dynamic models that capture the interaction between air cleaning, airflow, and energy consumption, suitable for EPBD compliance and simulation tools including simulation of indoor environmental parameters influencing gas-phase reactions and by-product formation.
A.3 Procedures for EPBD alignment: Create guidelines for integrating air cleaning performance into EPBD assessment schemes and regulatory frameworks to facilitate large-scale adoption.
Subtask B: Technology Integration and Control Strategies
Background
Integrating air cleaning with ventilation and HVAC systems is critical to achieving both high indoor air quality and low energy consumption. Many technologies—such as filtration, UV disinfection, photocatalysis, and plasma—operate independently without coordinated control. This lack of integration reduces their potential energy benefits and may lead to suboptimal operation. A systematic approach is needed to coordinate air cleaning and ventilation in real-world applications and ensure compatibility with building control systems and digital management platforms.
Purpose
Subtask B will investigate how advanced air cleaning systems can be optimally integrated and controlled within HVAC systems. The goal is to identify effective operational strategies and control algorithms that maximize energy efficiency while maintaining or enhancing IAQ under different occupancy and environmental conditions.
Strategy and Activity Structure
Subtask B includes three Activities focused on technology integration and control:
B.1 System integration concepts: Examine configurations combining mechanical and gas-phase cleaning systems with ventilation to optimize IAQ and energy use.
B.2 Control and automation strategies: Develop control logics and digital interfaces that enable dynamic operation based on occupancy, pollutant load, and outdoor conditions.
B.3 Validation and benchmarking: Test integrated systems under laboratory and semi-real conditions to establish performance benchmarks and identify optimal control approaches.
Subtask C: Resilience and Health-Centered Applications
Background
Recent global challenges—such as pandemics, wildfires, and overheating—have highlighted the need for resilient building systems capable of maintaining healthy indoor environments under stress. Air cleaning technologies play a central role in providing adaptive protection against airborne pathogens and pollutants during crises, yet their resilience performance is not well understood. There is a need to evaluate these technologies within a broader framework of health, safety, and adaptability. For emerging technologies such as photocatalysis, plasma, and ionisation, the Annex will include testing under realistic indoor conditions to evaluate performance and potential by-product formation.
Purpose
Subtask C will assess how air cleaning can enhance building resilience under extreme or abnormal conditions. It will explore the effectiveness of technologies in mitigating risks from infection, smoke events, and overheating, while maintaining energy-efficient operation and occupant comfort.
Strategy and Activity Structure
Subtask C comprises three Activities designed to explore resilience and health-centered performance:
C.1 Resilience scenarios: Define representative environmental and operational stress scenarios (e.g., wildfire smoke, infection outbreaks, heatwaves).
C.2 Health and exposure assessment: Evaluate air cleaner performance for removal of pathogens, particles, and gaseous pollutants under resilience conditions, and reduction in health risk index.
C.3 Adaptation strategies: Develop operational and design guidelines for resilient and health-centered buildings integrating air cleaning and ventilation.
Subtask D: Demonstration, Standardization, and Dissemination
Background
For air cleaning to become a recognized component of energy-efficient and resilient building design, evidence from real-world applications must inform standards, policies, and practice. Demonstrations, long-term field studies, and harmonized test methods are essential to validate performance claims,
improve regulatory acceptance, and accelerate market uptake.
Purpose
Subtask D will bridge research and practice by demonstrating real-world energy and IAQ benefits of air cleaning. It will also develop recommendations for test standards, certification, and dissemination activities to ensure that Annex outcomes have broad impact across scientific, policy, and industry communities.
Strategy and Activity Structure
Subtask D will include three main Activities focused on validation and outreach:
D.1 Field demonstrations: Conduct long-term monitoring and validation of air cleaning performance and resilience in representative non-residential buildings.
D.2 Standardization and certification: Develop recommendations for harmonized test methods and metrics for both particulate and gas-phase cleaning.
D.3 Dissemination and stakeholder engagement: Share results through reports, guidelines, webinars, and industry workshops to support EPBD implementation.