One of the important topics discussed constantly throughout the development of the heating, ventilation and air conditioning (HVAC) industry was that of identifying the best solutions based on chemical refrigerants. Whenever opting for one substance or another, producers in the area should consider getting a balance between the operating efficiency and the environmental impact of the product, in order to make the correct choice of material to replace the existing solutions. In this context, is important an overview of the most popular combinations used at the international level, while pointing out how the regulatory environment has evolved during the last period. Only in this way is it possible to lay some solid foundations for the subsequent development of new equipment, with optimized operation together with minimizing the risk operation. In the early years of development of this sector, the attention of the pioneers in this field was focused primarily on solutions for cooling, ensuring practically a level well defined of air conditioning systems with high efficiency. Therefore, many of refrigerants used in that era were the type of sulfur dioxide, methyl chloride and ammonia - materials which had the ability to fulfill the demands, but the use of which imply a high risk due to increased toxicity and large potential flammability. In the 30’s of the last century, on the market was introduced the CFC solution (chlorofluorocarbon), as an alternative to previous methods, providing an increase operational safety, minimizing the illness risk for users. CFC dominated the market for a long enough period, thanks to the excellent characteristics of efficiency and security. Improved version (hydrogenated type - HCFC) was a viable alternative since 1950, and it has been applied extensively in industry until the 70’s, when the international researchers have shown the negative impact that CFC's exercised over the ozone layer (responsible for the protection of the planet's surface against excessive harmful radiation).