Ozone Depletion Potential (ODP)

Ozone Depletion Potential (ODP) describes the extent to which a substance contributes to the depletion of the stratospheric ozone layer. The metric is commonly used to assess refrigerants and plays an important role in evaluating their environmental impact.

The former CFC refrigerant R11 serves as the reference substance and is assigned an ODP value of 1.0. Substances with a lower impact have correspondingly lower ODP values. Refrigerants that do not contribute to ozone depletion have an ODP of 0.

ODP and refrigerants

The ozone layer protects the Earth from harmful ultraviolet (UV) radiation. Certain chemical compounds – particularly substances containing chlorine or bromine – can break down ozone molecules in the atmosphere and contribute to long-term ozone layer depletion. Historically, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were among the primary contributors to ozone depletion. As a result, their use has been largely phased out or restricted worldwide.

Most modern refrigerants no longer have ozone-depleting properties. This includes many hydrofluorocarbons (HFCs) as well as natural refrigerants such as ammonia (R717), carbon dioxide (R744), and propane (R290), all of which have an ODP of 0.

Relevance for industrial heat pumps

However, a low ODP value alone is no longer sufficient to assess the environmental performance of a refrigerant. Today, Global Warming Potential (GWP) is an equally important consideration. Some refrigerants may have no impact on the ozone layer while still contributing significantly to climate change due to their high GWP. In practice, refrigerant selection therefore requires balancing multiple factors, including ODP, GWP, safety requirements, energy efficiency, and applicable regulatory requirements.

For industrial high-temperature heat pumps, selecting the right refrigerant is a key design consideration. Modern systems increasingly rely on natural refrigerants with an ODP of 0 and a low GWP, enabling the efficient and sustainable generation of high-temperature process heat.

The international framework for phasing out ozone-depleting substances was established through the Montreal Protocol, adopted in 1987. Today, reducing greenhouse gas emissions and supporting the long-term decarbonization of industrial processes are additional priorities shaping refrigerant selection and technology development.