Carbon Dioxide (CO₂) as a Low-GWP Refrigerant in Modern HVAC Systems

The HVAC industry is undergoing a profound transformation driven by environmental regulations, energy efficiency demands, and the urgent need to reduce greenhouse gas emissions. Among the most promising developments in this transition is the renewed adoption of Carbon Dioxide (CO₂), also known as R-744, as a natural, low-GWP refrigerant.Once considered impractical due to its high operating pressures and challenging thermodynamic behavior, CO₂ is now at the forefront of modern refrigeration and heat pump technology. Advances in compressor design, control strategies, and system architecture have turned what was once a limitation into a viable and increasingly attractive solution for supermarkets, industrial refrigeration, cold storage, and even heating applications.This book is written to provide a clear, practical, and engineering-focused understanding of CO₂-based HVAC systems. It bridges the gap between theoretical thermodynamics and real-world application, helping engineers, consultants, students, and decision-makers understand not only how these systems work, but also why they matter in the context of global sustainability goals.Rather than treating CO₂ refrigeration as a niche technology, this book positions it as a central pillar in the future of HVAC design.