Executive Summary
THERM-R is designed to optimise existing HVAC architectures progressively — not to universally eliminate roof-mounted package units.
Positioning
THERM-R is designed to work with existing HVAC architectures where practical and progressively optimise thermal performance through intelligent monitoring, control and resource management. It does not claim to universally eliminate or replace existing RMPUs.
How It Works
Zonal temperature and humidity sensors feed CORE-ERMC, which coordinates advisory optimisation commands to the existing HVAC controller — compressor loading, heat-exchanger monitoring and thermal analytics — while the underlying HVAC hardware and its safety interlocks remain unchanged.
This publication describes conceptual frameworks and proposed architectures. Where quantitative figures appear, they are engineering projections intended for planning and are subject to experimental validation.
R744 Clarification
TransO2 may investigate R744 / CO2 refrigeration architectures as a longer-term pathway. Captured CO2 is not automatically refrigerant-grade and cannot simply be transferred into a refrigeration circuit without purification, conditioning, certification and engineering validation. The CARB-X carbon-management pathway and the THERM-R R744 refrigeration pathway are not automatically the same physical CO2 stream.
Glossary
References
References point to established engineering disciplines and public frameworks, not fabricated citations.
- RDSO general rolling-stock HVAC practice (public reference)
- R744 / CO2 refrigerant engineering literature (general)
Suggested Citation
TransO2 Engineering Team. THERM-R: Working With, Not Replacing, Existing RMPUs. Knowledge Centre Publication EN-102. TransO2. v1.0. 2026.
About TransO2
TransO2 is developing a modular Environmental Operating System for railway rolling stock — integrating air, thermal, energy, safety, water and digital intelligence. Engineering concepts and performance targets are subject to detailed design, testing, validation and certification.