Emissions from refrigerant leakage accounted for 7.8% of worldwide greenhouse gas (GHG) emissions in 2019. Professor Graeme Maidment’s research into causes of leakage of refrigerant gas loss has had far-reaching impact in GHG emissions reduction, including contributing to the UK net zero legislation.
Many of the estimated five billion refrigeration, air-conditioning and heat pump (RACHP) systems in use globally use chemical refrigerants with significant global warming potential (GWP), where a single kilogram can cause as much atmospheric damage as 3900kg of carbon dioxide.
Emissions from refrigerant leakage accounted for 7.8% of worldwide greenhouse gas emissions in 2019. These losses also reduce the efﬁciency of refrigeration systems, leading to indirect emissions through increased fuel consumption and higher maintenance costs.
All refrigeration systems have the potential to leak because pressures in the system are usually many times higher than atmospheric pressure. Professor Graeme Maidment and his team at London South Bank University (LSBU) have been carrying out research into refrigeration leakage for over 15 years, focusing on ascertaining the scale and critical sources of refrigerant leakage and reducing fluorinated gas (F-gas) leakage from stationary sources and refrigerated vehicles.
The UK Refrigerant Emissions And Leakage Zero (REALZero) project, which commenced in 2008, was undertaken by the Institute of Refrigeration and LSBU. The Carbon Trust-supported project researched the scale and causes of leakage of refrigerant leakage, investigating 81 systems across 25 UK sites during 2008/9, including retail, building air conditioning, cold storage and industrial processing. Follow-up surveys in 2010 showed a net reduction in annual refrigerant use of 4905kg in 2009/2010 compared with 2008/2009, representing a reduction of 43% in direct emissions, as a result of the interventions designed by LSBU.
The results of Maidment’s research resulted in a comprehensive set of training materials and monitoring tools to help equipment operators and technicians reduce refrigerant leakage. The original REALZero work led to international programmes. REALSkillsEurope extended the leakage reduction training and awareness into Europe, while REALAlternatives focuses on low GWP alternatives to F-gases.
The transition to low GWP refrigerants is critical to reducing the projected 70,000,000t CO2e emissions from the sector by 2030. REALAlternatives’ aim is to enable the safe use of low GWP alternative refrigerants such as carbon dioxide, ammonia, hydrocarbon and new low flammables HFOs and R32. While these are preferable in terms of their global warming potential, they present a greater health and safety risk so REALAlternatives is designed to improve training capacity, the skills levels of installers plus knowledge and awareness levels in the RACHP market. The project set up European training centres and associations in partnership with the IIR to provide “Train the Trainer” sessions on low GWP refrigerants.
LSBU is one of six international project partners in the REALAlternatives Consortium, with responsibility for clarifying alternative refrigerant training needs and opportunities in Europe, developing a specification for the e-learning, and reviewing resources currently available in Europe to support learning. LSBU provides research capability for the consortium.
The commercial refrigeration industry is responsible for 40% of total annual refrigerant emissions despite accounting for only 22% of worldwide refrigerant consumption. Maidment’s research into commercial refrigeration systems established that pipe/joint failure and leaking seals/valves account for over 53% of total average refrigerant mass loss.
Maidment was credited as an expert by the UK Climate Change Committee (CCC) on reducing F-gas emissions, to which he provided evidence. The resulting report, ‘Assessment of potential to reduce UK F-gas emissions’, supports the CCC’s Net Zero technical report, which in turn informs the final CCC Net Zero advice report. The recommendations of this final report were turned into legislation committing the UK to net zero emissions by 2050, passed in 2019.
The findings from the REALZero work prompted The International Institute of Refrigeration (IIR) to set up a Working Party on "Mitigation of Direct Emissions of Greenhouse Gases in Refrigeration". The working party developed a position paper (published 2014) on minimising leakage of refrigerants, recommending actions for reducing leakage, replacing the previous guidance from 1999.
REALZero is also included in the US Environmental Protection Agency’s (EPA’s) industry resources and reports related to its GreenChill programme aimed at enabling food retailers to reduce refrigerant emissions.
In 2000 Asda had 250 stores with refrigerant loss of 50% per annum. In 2020 the retailer had 620 stores, representing a 200% increase in shopfloor space, but refrigerant gas leakage is less than 10%:
To address its refrigerant losses, Asda started examining ways to reduce energy and carbon usage, in 2007 and has credited REALZero with enabling it to achieve improvements in this area: “The work of Graeme, LSBU and the Institute of Refrigeration has been the guiding light for Asda…F-gas regulations were important and we had to go down this route. We bought into REALZero and certainly have no regrets.” [Testimonial from Asda]
Primary food distribution by refrigerated road transport (RRT) in the UK uses up to 37% more energy than comparable non-refrigerated vehicles. Moreover, RRT vehicle engines account for 2% of the total CO2 emissions from the UK road sector. Efficiency improvements could achieve up to 50% energy savings for chilled goods transport. Maidment’s research into this area found that RRT systems were more prone to leaks than stationary systems, particularly in the case of poorly maintained older vehicles.
The LSBU team subsequently worked with Hubbard, a British based HVAC company active in the refrigerated vehicle sector, to analyse where energy and carbon savings could be made. Examination of 200 vehicle logs identified the areas most prone to leakage, and therefore opportunities to address this.
Collaboration between Hubbard and LSBU resulted in the design of a new component as a simple way to reduce leakage, creating a multi-million pound market. The new component replaced a flare connection with an O ring: “[LSBU] research had shown that a key leakage point was a seal between the high-pressure dryer filter and the sight gauge. We created a modified design to address this and marketed a new unit. This is replaced annually on over 100,000 trucks in the UK; its trade price is £31.” [Hubbard]
Recent years have seen a growth in demand for temperature-controlled refrigerated delivery services in response to the increase in online shopping. Maidment’s research on the integrity of transport refrigeration systems informed the development of a British Standard for refrigerated vehicles in 2017 (PAS 1018:2017) and subsequently to an international equivalent, ISO 23412:2020.
ISO 23412 is the first international recognised standard for indirect, temperature-controlled refrigerated delivery services via land transport. It sets out requirements for refrigerated delivery service providers so that they can improve the quality and consistency of refrigerated parcel delivery services in a range of sectors, including cold chain and courier services. The first company to obtain ISO 23412 certification was Yamato in September 2020.