ISO 5222-2:2025

Overview

ISO 5222-2:2025 specifies standardized testing and calculation methods for the sensible cooling recovery seasonal performance factor (Fsc) of heat recovery ventilators (HRV) covered by ISO 16494-1. The document defines test conditions, procedures and rating rules (including default outdoor temperature bin distributions in Annex B) used to determine how effectively an HRV recovers sensible cooling over a cooling season. Procedures in this part can also be applied to other temperature conditions.

Key topics and technical requirements

• Scope and definitions: Clarifies terms such as sensible cooling heat recovery, gross sensible cooling effectiveness (εsc), bypass ventilation function, bypass outdoor temperature (Tb) and seasonal performance factor (Fsc).
• Standard test conditions: Specifies five reference test conditions (T1/T2/T3/T4/T8) with defined indoor/outdoor dry- and wet-bulb temperatures for cooling performance tests. These are aligned with ISO 16494-1 test methods.
• Measured metrics:
  • Gross sensible cooling effectiveness (εsc)
  • Sensible cooling recovery capacity and seasonal cooling energy recovered (Esc)
  • Power input characteristics including fan power with and without bypass (Pin)
  • Seasonal performance factor Fsc (ratio of seasonal recovered sensible cooling to HRV electricity input)
• Bypass control and Tb: Procedures to determine or verify a unit’s bypass outdoor temperature (manufacturer-specified or calculated per Annex D) and test protocols for HRVs with bypass ventilation.
• Test procedures and instrumentation: Conformance with ISO 16494-1 for measurement accuracy, airflow, static pressure and efficiency tests; requirements for test reports (Annex E template).
• Calculation framework: Bin-hour based method using outdoor temperature bins (Annex B), characteristics of recovery capacity vs. outdoor temperature, and seasonal aggregation procedures (Annex C for application-specific cooling load scenarios).

Practical applications - who uses this standard

• HRV and HVAC product manufacturers - to design, validate and declare seasonal cooling performance.
• Independent test laboratories - to run reproducible performance tests and verify manufacturer claims.
• Certification bodies and regulators - for energy labeling, compliance and performance benchmarks.
• Specifiers, consulting engineers and building energy modelers - to compare HRV options, size ventilation systems and estimate seasonal energy savings in cooling climates.
• Facility managers and energy auditors - to evaluate retrofit opportunities and operational settings (including bypass control) that affect seasonal efficiency.

Related standards

• ISO 16494-1:2022 (and Amendment 1:2023) - referenced normative test methods and performance metrics for HRVs/ERVs; ISO 5222-2 is intended to be used together with ISO 16494-1.

Keywords: ISO 5222-2:2025, heat recovery ventilators, HRV, sensible cooling recovery, seasonal performance factor, testing methods, bypass ventilation, ISO 16494-1.