| REFRIGERANTS refrigerants that have thermodynamic properties that provide a more efficient refrigeration cycle. Unfortunately, refrigerants that have lower environmental impact are not always those that deliver good thermodynamic performance or overall life-cycle benefit. The hydrofluorocarbons (HFCs), which have zero ozone depletion potential, rose in popularity for use in refrigeration, air conditioning and heat pump equipment as CFCs and HCFCs were phased out. Most of the HFCs are thousands of times more harmful to the climate as GWP gases (see Global warming boxout), compared with the refrigerants they replaced. The UN identifies a variety of impacts from the resulting climate change, such as: soil erosion; more crop diseases; reduced water availability; hunger and malnutrition; heat-related illnesses; wildfires; shifting fish stocks; losses of habitat for wildlife; and the melting of ice and snow that is raising sea levels In response to the rapid growth of HFC emissions, the Montreal Protocol adopted the Kigali Amendment in 2016 to gradually reduce the global production and consumption of HFCs. It is estimated that phasing out HFCs will avert global temperatures from rising by 0.5K by the end of the century and, if accompanied by better energy efficiency measures, will potentially avoid one-degree celsius of warming.3 Refrigeration is set to be one of the fastestgrowing sources of warming emissions, as incomes rise in developing countries, temperatures increase, and global cooling demand soars. More than one billion people presently face immediate risks from a lack of cooling, and a warming planet means this number will only increase and meeting that cooling demand will itself contribute to heating the planet. Left unchecked, direct and indirect emissions from air conditioning and refrigeration are projected to rise 90% above 2017 levels by 2050,4 resulting in an increase in greenhouse gas emissions equivalent to one-third of all current emissions. The Kigali Amendment was welcomed by many chemical and manufacturing companies in developed countries because it can endow them with green kudos and market advantage over inferior products. It was much harder for developing countries, as their companies have relied on old refrigeration and coolant technologies, and need to invest in research and development, and upgrade or replace factories and equipment. The HFC phase-down provides an opportunity to combine other energy efficiency measures, alongside developing energy efficient and environmentally responsible refrigerants. The details of the 2010 global greenhouse gas emissions from air conditioning 450 400 350 Emissions (MMTCO2e) CPD PROGRAMME 300 250 200 150 100 50 0 Residential A/C Commercial A/C Figure 1: The global emissions, in million tonnes CO2 equivalent, from the cooling component of air conditioning systems from direct and indirect emissions, based on 2010 data (Source: US Dept of Energy, The future of air conditioning for buildings (2016)) agreed Kigali Amendment are quite complex, providing a different trajectory for substance phase-out that largely depends on a countrys per capita consumption of controlled substances. Developed countries, being larger per-capita consumers, have a shorter reduction timetable compared with the developing nations (as defined by Article 5 of the Montreal Protocol). Non-Article 5 countries, including the US, Japan and in Europe, formally started phasing out HFCs in 2019. China will start in 2024, and India and other more challenged countries in 2028. Non-Article 5 countries have agreed to cut the use of HFCs to 15%, against an agreed baseline, by the mid-2030s, and Article 5 countries to similar levels by the late-2040s. Until the 1980s, there had been only gradual change in refrigerant choices over the previous half-century. In the past 40 years, however, there has been a steady change in the application of refrigerants, as shown in Table 1. (The categories synthetic and natural can be somewhat misleading, as manufacturing processes are likely to be required for both types of refrigerants.) The majority of HFC consumption is in the cooling sector, comprising refrigeration, air conditioning and heat pumps, and more than half of that total HFC consumption is thought to come from emissions resulting from the servicing of installed equipment.7 As a result of the Kigali Amendment and, in Europe, the GLOBAL WARMING Global warming potential (GWP) is a measure of the relative global warming effects of different gases. It assigns a value to the amount of heat absorbed by the gas relative to that of a similar mass of carbon dioxide over a specific period. Carbon dioxide was chosen as a convenient benchmark gas by the Intergovernmental Panel on Climate Change (IPCC), and its GWP is taken as 1. As shown in Figure 2, 2019 was characterised by warmer-than-average conditions across most of the global land and ocean surfaces, with record high annual temperatures being experienced across many parts of the world. At current rates of growth, by 2024/25 levels of atmospheric CO2 will be higher than at any point in the past 3.3 million years (since the Mid-Piacenzian Warm Period), when mean global temperatures were 2K to 3K higher than today.5 Land and ocean temperature departure from average Jan-Dec 2019 (with respect to a 1981-2010 base period) Data source: NOAAGlobal Temp -5 -4 -3 -2 -1 0 1 Degrees celsius 2 3 4 5 Please note: grey areas represent missing data map projection: Robinson Figure 2: Comparative average global temperatures for 2019 (Source: www.ncdc.noaa.gov/sotc/global/201913) 64 September 2020 www.cibsejournal.com CIBSE September 2020 p63-66 CPD 167 v2.indd 64 21/08/2020 15:28