The ideal refrigerant has not been developed, so choosing the best one involves balancing factors like optimizing performance, minimizing environmental impact, controlling costs, and ensuring user safety.
Every HVAC equipment manufacturer considers these factors to ensure they provide the best product to their customers. Each owner must also consider the refrigerant used in equipment options for their short-term and long-term goals; the type of refrigerant used could be a key factor when deciding between different HVAC manufacturers that use different refrigerants in their equipment. This refrigerant choice must also align with the regulations that government authorities, such as ASHRAE, establish to make HVAC equipment safer for the environment. The two main choices going forward for the HVAC industry are either R-32 or R-454B.
Factors to consider:
- Performance accounts for the chemical stability, latent heat of vaporization, thermal conductivity, and viscosity of a refrigerant. Each of these factors contribute to the capacity, life, and efficiency of a DX piece of equipment.
- If the cooling equipment must be larger to get the same capacity because of the refrigerant performance, the customer must pay for this increased capacity, preventing these dollars from being invested in other initiatives.
- Reduced life of equipment because of refrigerant choice does not have an immediate cost implication, but certainly does over the life of building ownership due to increased frequency of replacement.
- Efficiency is important to the customer as it directly impacts energy bills, but it also needs to be considered as an important part of meeting environmental goals. The more energy consumed results in the need for increased power production and in turn increasing emissions.
- Besides increased emissions, reducing power demand becomes increasingly more important as energy prices rise, and the power grid becomes less reliable.
Based on the evolution of refrigerants and the associated policies being applied world-wide, the direct impact of refrigerants on the environment is an issue. Since new building development continues around the world and the demand for cooling using refrigerants will continue to increase, the decision regarding refrigerants is especially impactful.
Primary focus has turned to Global Warming Potential (GWP) when it comes to the impact of refrigerants on the environment. GWP is an index describing a refrigerant’s relative ability to trap radiant energy compared to carbon dioxide over a period of 100 years. The higher the GWP value, the more that refrigerant warms the Earth compared to carbon dioxide. Every refrigerant is assigned a GWP value that can be referenced when comparing options. It is anticipated that the GWP value will continue to decrease over time with the implementation of more environmental policies and practice.
Cost of Change
Any costs associated with transitioning to a new refrigerant are absorbed into the price of new equipment. Extensive investments are required for the research and development of new refrigerants and the costs of scaling them to meet the increased market demand. Refrigerant manufacturers pass these costs on to the HVAC manufacturers. New refrigerants often operate at different pressures than the previously used refrigerant, which requires HVAC equipment to be redesigned and retooled. Redesigned equipment requires recertification for compliance with industry safety and efficiency standards. All these factors can lead to an increase in equipment costs.
Ensuring User Safety
A new refrigerant classification has been identified to meet expected lower GWP mandates – A2L classification.
ASHRAE Standard 34, classifies refrigerants according to their toxicity and flammability using a letter and number designation. The first digit is a letter associated with toxicity. An ‘A’ indicates that the refrigerant has a low toxicity level which is typical of refrigerants used in HVAC applications. To qualify for this classification, the acceptable operational exposure limit (OEL) to the refrigerant is equal to or greater than 400ppm. The second digit, the numerical reference, indicates the level of risk associated with flammability. The current refrigerants being phased out for A2L refrigerants are classified as A1 – which means they had no flame propagation and a lower toxicity.
A2L was introduced as a new separate category in the 2016 edition of ASHRAE Standard 34 in response to the need to target refrigerants that were less damaging to the environment. Although flammable, these A2L refrigerants are difficult to ignite, do not sustain ignition well, and propagate flame spread slowly. This was considered an acceptable compromise considering the minor risk posed when compared to the positive environmental impact. It was also anticipated that building codes would be modified to mitigate the risk to no more than that of using A1 refrigerants.
Not only are modifications required to building codes as the result of the introduction of more flammable refrigerants (A2L classification), but HVAC equipment manufacturers also have new safety requirements to which to abide.
Comfort heating and cooling systems are designed to serve people in buildings. The safety of these occupants must always remain a priority. The risk associated with flammability and toxicity in the case of a leak are both considered based on the application and potential exposure. A2L refrigerants require new and more stringent provisions in the safety standards for HVAC equipment. These safety standards are focused on the mild flammability of A2L classification and include additional features required to address leaks that could create a fire hazard. For HVAC equipment going forward, the two most selected A2L refrigerants are R-32 and R-454B.
Adding additional but necessary safety features contributes to an increase in the costs of HVAC equipment. Increased equipment cost is not the only added expense that results from a refrigerant change. In the case of A2L refrigerants, the changes to building design and construction requirements to maintain the same level of safety to building occupants increases construction costs.
The short-term alternative is to service and recharge existing equipment with its existing A1 classified refrigerant. The problem with this alternative is that it is expected that these A1 refrigerants that are being phased out will increase in cost as the production of them are shut down and existing supply becomes more limited.