ISO 14505-2:2026 Determination of equivalent temperature-Lab Testers

Basic Standard Profile

Full Title: Ergonomics of the thermal environment — Evaluation of thermal environments in vehicles — Part 2: Determination of equivalent temperature

Edition: Updated version published 12-Feb-2026, superseding ISO 14505-2:2006

Standard Positioning: Core part of the ISO 14505 vehicle thermal ergonomics series, establishing unified testing rules for equivalent temperature calculation inside vehicle cabins and similar asymmetric confined spaces

ISO 14505-2:2026 is an international standard developed by ISO, focusing on ergonomics of the thermal environment with a specific emphasis on evaluating thermal environments in vehicles. This standard outlines requirements and recommendations for assessing the thermal conditions inside a vehicle compartment, but it is also applicable to other confined spaces characterized by asymmetric climatic conditions. The guidance is particularly relevant when deviations from thermal neutrality are relatively small.

A major part of the standard is the determination of equivalent temperature, a scientifically-based measure that integrates the effects of convection, radiation, and, where relevant, conduction and evaporation, to describe the thermal stress experienced by occupants.

Core Covered Topics

Equivalent Temperature (teq)

This is a unified metric that integrates convective and radiative effects, representing the temperature of a homogeneous environment where a person would experience the same heat exchange as in the measured space.

Whole Body Equivalent Temperature

Assesses the net heat exchange affecting the entire body, typically measured using thermal manikins with multiple zones that simulate human thermoregulation.

Segmental Equivalent Temperature

Focuses on specific body parts or segments, such as the hands, head, or thighs, providing localized thermal assessment.

Directional and Omnidirectional Equivalent Temperature

Employs specialized sensors to capture both targeted and averaged heat exchange over a defined area or direction, useful for detailed climate mapping inside compartments.

Equivalent Contact Temperature

Introduced in this edition, this concept addresses the impact of direct body contact with surfaces (like seats), accounting for heat conduction and local moisture effects.

Measurement and Calibration

The standard includes comprehensive recommendations for selecting and calibrating measurement instruments, such as thermal manikins and various sensors, to ensure consistent and valid results.

Primary Application Scenarios

Vehicle Manufacturers

Ensuring occupant comfort and optimizing HVAC performance during vehicle development and testing.

Automotive HVAC Engineers

Evaluating and comparing different heating, ventilation, and air conditioning systems using a standardized thermal measurement methodology.

Ergonomics and Human Factors Specialists

Assessing human thermal comfort and local discomfort in vehicle cabins and designing environments for enhanced wellbeing and safety.

Testing Laboratories and Certification Bodies

Providing a benchmark method and terminology for validating climate conditions within vehicles or similar confined spaces.

Researchers and Designers

Studying the effect of non-uniform climates and direct surface contact on human thermal sensation, especially in complex environments like modern vehicles.

Reference Standards

ISO 13731: Ergonomics of the thermal environment - Vocabulary and symbols

ISO 14505-1: Ergonomics of the thermal environment - Evaluation of thermal environments in vehicles - Part 1: Principles and methods for assessment of thermal stress

ISO 14505-3: Ergonomics of the thermal environment - Evaluation of thermal environments in vehicles - Part 3: Evaluation of thermal comfort using human subjects

ISO 14505-4: Guidance for use of equivalent temperature models with thermal manikins

SAE J2234: Standard practice for measuring and reporting directional heat exchange in vehicle environments

Closing Summary

By adopting ISO 14505-2:2026, organizations can standardize thermal comfort evaluation, objectively compare HVAC solutions and vehicle designs, satisfy climate-control related regulatory and customer demands, acquire repeatable test data for R&D and quality control, and realize globally consistent thermal assessment for vehicles and analogous confined spaces.