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20 Years of the Montreal Protocol

Sept. 1, 2007
September 2007 marks the 20-year anniversary of the Montreal Protocol, a global agreement concerning the phaseout of ozone-depleting substances (ODSs),

September 2007 marks the 20-year anniversary of the Montreal Protocol, a global agreement concerning the phaseout of ozone-depleting substances (ODSs), including chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). Ratified by more than 190 countries, the Montreal Protocol is one of the most successful international environmental treaties in terms of global coordination and cooperation. Global participation is critical because impacts on ozone depletion are the same, regardless of the location of ODS emissions.

In terms of performance, the Montreal Protocol has been a success, specifically in stabilizing or decreasing levels of ODSs in the atmosphere. Over the last few decades, rigorous monitoring and analysis of the ozone layer has shown early signs of ozone recovery.1 This progress is fragile, however; any failure to comply with the protocol's requirements moving forward will threaten the advancements to date. Therefore, it is important for industries that rely on ODSs, such as the HVACR industry, to take immediate action. To that end, governments and regulatory bodies around the world are advocating accelerated phaseout of HCFCs.

This article will discuss the past, present, and future of the Montreal Protocol. First, it will examine requirements of the protocol, focusing on how the agreement has impacted the HVACR industry. Next, it will highlight positive outcomes stemming from the protocol over the last two decades. Finally, it will discuss the protocol's impact on the “health” of the ozone layer, the next essential steps toward meeting the agreement's ultimate objectives, and challenges that lie ahead.


Although the ozone-depletion findings that prompted the development of the Montreal Protocol were grounded in years of sound, scientific research, the architects of the agreement understood that ozone science and technology are not static. They anticipated the need to modify the agreement based on new scientific assessments, as well as improved technical and economic information. This flexibility is one of the key features of the Montreal Protocol. Another key feature is the freedom the protocol gives individual countries to decide how best to meet reduction targets based on their unique domestic situation. For example, in the United States, the Clean Air Act requires the Environmental Protection Agency (EPA) to establish rules for phasing out consumption (defined in the protocol as “production plus import minus export”) of ODSs.

The Clean Air Act outlines phaseout requirements for two classes of ODSs. Class I includes CFCs. Consumption of CFCs — excluding use as feedstock and minor essential uses — already has been banned. Class II is comprised of HCFCs, which will be the focus of incremental stepdowns in consumption over the next two decades.

Although the protocol does not specify a means of ODS elimination, it does require countries (“parties”) to achieve certain percentage reductions by specific dates. Progress is measured against a baseline consumption cap. For developed countries, the cap is 2.8 percent of a country's 1989 CFC consumption plus 100 percent of that country's HCFC consumption, both on an ozone-depletion-potential- (ODP-) weighted basis.2

Through the Clean Air Act, the United States has implemented its own schedule and actions to meet the protocol's timeline (Table 1).

To ensure protocol targets are met, the U.S. EPA also allocates consumption allowances for HCFCs. The current rule regarding these allowances extends through 2009. The EPA, however, already has begun the process of rulemaking to set allowances for 2010 and beyond.

Impact on the HVACR industry. As a primary consumer of CFCs and HCFCs, the HVACR industry has had to make significant adjustments to the way it develops, installs, services, and maintains air-conditioning and refrigeration systems to ensure compliance with the Montreal Protocol's phaseout requirements. During the first years of the treaty, the industry was focused on meeting the Jan. 1, 1996, deadline for zero consumption of CFCs. In many cases, businesses met the deadline by converting to lower-ODP HCFC refrigerants. Now, new deadlines loom. By 2010, the United States must achieve a 65-percent reduction in consumption of HCFCs; by 2015, it must achieve a 90-percent reduction. Unless industry practices change, HCFC-22 shortages will be seen starting in 2015.3

Mandatory reductions of virgin HCFC-22, the most abundant HCFC in the atmosphere, with the highest total contribution to ozone depletion, will impact the overall supply of HCFC-based refrigerants. Consequently, the industry needs to make dramatic changes to refrigerant-recovery practices and, where practical, replace, or retrofit with HCFC alternatives, existing equipment. Specifically, increased reuse of HCFC-22 will be essential to satisfying servicing needs. This will necessitate an increased focus on leak repair and recordkeeping requirements, as well as recovery practices. Building owners and managers should work with HVACR contractors to understand new-equipment and retrofit refrigerant options with zero ODP, such as hydrofluorocarbons (HFCs).


Developed and developing countries alike have made significant progress thus far. Developed countries have phased out the production and consumption of more than 99 percent of all chemicals controlled by the Montreal Protocol,4 while developing countries, which are subject to a slightly different phaseout schedule, have achieved a CFC reduction of more than 72 percent and met most of the protocol's phaseout goals significantly ahead of schedule.4 Additionally, many countries — both developed and developing — have exceeded expectations by keeping consumption levels below those allowed by the protocol.4

According to the World Meteorological Organization (WMO),1 amounts of ODSs in the atmosphere are consistent with, or decreasing from, previous levels. By 2005, the total amount of human-produced ozone-depleting gases in the troposphere had decreased by 8 to 9 percent from the peak observed from 1992 to 1994.1 Ozone-depleting gases in the stratosphere also are showing a downward trend from their peak values of the late 1990s.1 If levels of ozone-depleting gases continue to decline, the WMO projects that global ozone levels will return to pre-1980 values — a benchmark for ozone recovery — by the middle of the 21st century.1

According to a 2002 assessment,5 “The Montreal Protocol is working, and the ozone-layer depletion from the protocol's controlled substances is expected to ameliorate within the next decade or so.” This prediction is highly plausible, but only as long as parties to the protocol sustain or enhance their efforts to eliminate ODSs.


Even though the net amount of ODSs in the atmosphere is decreasing, levels of HCFCs are on the rise. According to “Scientific Assessment of Ozone Depletion: 2006,”1 of the additional actions that could be taken to protect the ozone layer, decreasing production of HCFCs would have the greatest effect. As a result, there are six proposals from countries, including the United States, or groups of countries to accelerate the phaseout of HCFCs.

Commercial-building owners and managers can avoid HCFC-22 shortages and have a measurable impact on future HCFC levels by taking action now. This includes:

  • Understanding HCFC-phaseout requirements and deadlines. Although the HCFC-phaseout schedule has been widely discussed for more than two decades, many in the industry have not yet begun to address the upcoming stepdowns because they either are not aware of the regulations or are not clear on how to comply. With the next major HCFC-reduction deadline in 2010, it is important that building owners and managers understand the phaseout requirements and take appropriate action sooner, rather than later.

  • Minimizing HCFC emissions by repairing leaks and following EPA recordkeeping requirements. Proper design and installation of equipment is the first step in decreasing leaks. With equipment with a refrigerant charge of 50 lb or more, system performance must be tracked. When equipment exceeds acceptable leakage rates, repairs must be made within 30 days.

  • Adhering to correct recovery and reclamation practices. According to Section 608 of the Clean Air Act, recovered refrigerant can be stored and reused by the same owner; if it is to be used by a different owner, it must be reclaimed — cleaned to ARI 700-2006, Specification for Fluorocarbon Refrigerants, standards and chemically analyzed — by an EPA-listed refrigerant reclaimer.

  • Retrofitting existing equipment with zero-ODP alternative refrigerants. HFC retrofit refrigerants perform equal to, if not better than, HCFCs and decrease dependence on HCFC-22. Further, they enable continued use of existing equipment and minimize business disruption and downtime. Lastly, they facilitate compliance with environmental regulations and are subject to neither the Montreal Protocol phaseout schedule nor Clean Air Act recordkeeping requirements (although they still should be managed responsibly).

  • Increasing awareness of new equipment designed for HFC refrigerants. New equipment designed for HFC refrigerants is a viable option when a system must be replaced because of age or excessive leakage.


As nations around the world evaluate new technologies and regulations to continue ODS reduction and further mitigate damage to the ozone layer, they face several challenges. One is the illegal trade of restricted ODSs, which may increase as phaseout deadlines approach. Another is the remaining supply of ODSs in equipment and products, which, if not destroyed, likely will be emitted over the next few decades and partially counteract the progress that has been made thus far.


The Montreal Protocol is widely regarded as a model for addressing global environmental issues. Progress over the last 20 years has been rapid, with actions leading to significant reductions in the risk of ozone depletion. This has created an opportunity for the HVACR industry to introduce safe, efficient, cost-effective refrigerants with zero ozone-depletion potential. Still, it is premature to assume that all of the protocol's objectives have been met.

While existing phaseout requirements have reduced ODSs, many in government and industry believe more must be done to ensure recovery of the ozone layer. Building owners and managers should work with HVACR contractors on the phaseout of HCFCs. Also, they should anticipate more aggressive stepdown schedules as countries seek to increase momentum and promote a more rapid transition to non-ODSs. The implementation of new or revised regulations will help ensure that the goals of the Montreal Protocol are met and that the ozone layer is protected for future generations.


  1. WMO. (2007). Scientific assessment of ozone depletion: 2006. Geneva, Switzerland: World Meteorological Organization. Available at

  2. U.S. EPA. (2006). HCFC phaseout schedule. Available at

  3. ICF International. (2006). The U.S. phaseout of HCFCs: Projected servicing needs in the U.S. air-conditioning and refrigeration sector. Available at

  4. UNEP. (2007). A success in the making: The Montreal Protocol on substances that deplete the ozone layer. Nairobi, Kenya: United Nations Environment Programme. Available at

  5. UNEP/WMO. (2002). Executive summary, scientific assessment of ozone depletion: 2002. United Nations Environment Programme/World Meteorological Organization. Available at

The chief atmospheric scientist for DuPont, Mack McFarland, PhD, has more than 30 years of experience in atmospheric and ozone science. He was on loan to the Atmosphere Unit of the United Nations Environment Programme in 1995 and 1996 and the Intergovernmental Panel on Climate Change Working Group II Technical Support Unit in 1997. Over the years, he has participated in nearly every major international scientific assessment of stratospheric ozone and global climate change as author, reviewer, or review editor.

For past HPAC Engineering feature articles, visit


Although HFC refrigerants do not contribute to ozone depletion, they do have significant global-warming potential. With increased focus on protecting the global climate system, HFC emissions are coming under greater scrutiny. Regulations on HFCs have been passed in Europe and are in bills that are before Congress. Meanwhile, California is looking to regulate some applications. Industry must improve its handling of HFCs or face ever-more-stringent restrictions.


On Feb. 28, HPAC Engineering produced “Ozone Depletion, Global Warming, and Your Business,” an hour-long Webcast sponsored by DuPont Refrigerants and presented by Mack McFarland, who provided an overview of the most recent scientific findings, discussed existing and developing regulations, and shared strategies for meeting global environmental challenges. To view the Webcast, which will be archived for one year, visit

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