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Analysis of refrigerant leakage data REAL Zero

Chapter 4. Analysis of the emissions associated with RACHP systems

4.4 Analysis of refrigerant leakage rates and the causes of leakage

4.4.1 Analysis of refrigerant leakage data REAL Zero

One of the first such studies was a project titled ‘REAL Zero’ (Refrigerant Emissions and Leakage – Zero), led by the UK’s Institute of Refrigeration and carried out in partnership between industry and academia. The author was the project manager and responsible for collating and analysing the data collected from site surveys.

The investigation included surveys of 81 systems on 26 sites, using a methodology developed specifically for the project. The site survey format included:

• A detailed visual inspection of the system to check for general condition, operational status, cleanliness, corrosion, evidence of poor design, installation or maintenance practices and visual indications of refrigerant leakage (e.g. oil stains) and potential leakage points

• Using available F Gas and service records to calculate the CO2 equivalent emissions and the cost of the refrigerant added to the system during maintenance activities

• A consultation with site staff to obtain feedback on system reliability, historical problems and trends

• A detailed leak check, using a portable electronic leak detector, covering all accessible parts of the system, including components, pipe work, joints and auxiliary components such as pressure switches and pressure relief valve vent lines

The information was captured on site survey record sheets and used to prepare detailed survey reports for site owners that included a financial and environmental impact statement, a recommended leak reduction strategy and specific actions that should be undertaken to address the issues identified by the survey.

The surveys covered several different types of RACHP system including Large Retail (supermarket), Building Air Conditioning, Cold Storage, Industrial Processing and Small Retail. They revealed a varied implementation of the F Gas logs. The refrigerant records that were available covered periods of typically 12–18 months and the total CO2 equivalent direct refrigerant emissions from the 56 systems for which records were available were over 20,000 tonnes, at an estimated replacement refrigerant cost of £115,000. The results are summarised in Table 4-2..

Table 4-2. Summary of results from REAL Zero site surveys

Parameter Data Value

No. of sites analysed 26 No. of these sites with useful leakage data 23 Total number of refrigeration packs 81 Total number of pack leakage records 56 Average period covered by records (months) 13 Total Refrigerant Usage over Period Recorded (kg) 7,908

Total Refrigerant Cost Over Period Recorded (£) 114,593 Potential Cost Savings for 25% reduction (£) 28,648

Total CO2 equivalent emissions (tCO2e) 20,439

Potential CO2e savings for 25% reduction (tCO2e) 5,110

Figure 4-11 shows the annualised refrigerant use for 51 of these systems as a percentage of the system charge and indicates that in a few instances the total system charge was lost on more than one occasion.

Figure 4-11. 12 month equivalent refrigerant use for 51 systems (from REAL Zero project)

There was a significant variation between different types of site, but the sample was too small and the data too variable in quality to be able to provide a statistically significant graph on refrigerant leakage by sector. Energy consumption records were not available for the systems surveyed, but calculations performed using the reported cooling capacities, together with conservative assumptions for the COP and duty cycle, indicated that the direct emissions due to refrigerant leakage were of a similar magnitude to (and in some instances greater than) the indirect emissions for many systems. This confirmed the important role that reducing refrigerant leakage can play in improving the sustainability of large scale refrigeration systems.

96 refrigerant leaks were detected using calibrated leak detectors during the site surveys, the severity varying between ‘minor’ and ‘severe’ (the leak detectors were capable of detecting leakage rates of as little as 5g per annum). Many systems were found to be short of refrigerant at the time of the inspection and potential leakage points such as Schrader and service valves were not always capped. In many instances the approach to service and maintenance appeared to be reactive (responding to faults that had already occurred) rather than proactive and there was often no evidence of regular leak testing being performed. Another issue was that many leak detectors used by equipment maintainers had not been verified or calibrated on a regular basis, resulting in the possibility of incorrect operation when performing leak tests. 0% 100% 200% 300% 400% 500% 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 1 2 M o n th Eq u iv a le n t L e a k a g e R a te % System No.

The information obtained from the system site surveys was used to develop a set of REAL Zero support materials and tools, including:

 Guidance notes and advice for service and maintenance engineers, design engineers, service companies and equipment owners on topics such as common leak points, good practice in leak testing, new system design, maintenance contracts and legal responsibilities under the F Gas Regulations

 Software tools to keep track of and value the carbon case for refrigerant management

 A methodology and tools for undertaking site surveys and developing leakage reduction strategies and

A training and on-line assessment scheme, aimed at developing specialist skills in refrigerant management and leakage reduction techniques

Two software tools developed as part of the REAL Zero project were an Excel Workbook for F Gas logging and management reporting of refrigerant use and associated carbon emissions and a carbon and financial impact calculator that could be used to help develop a business case for measures to reduce refrigerant leakage. The F-Gas and ODS Regulations require that equipment owners keep a record of leak checks and service and maintenance activity related to refrigerant use. The keeping of such records is essential to developing a clear understanding of the potential to reduce refrigerant use in individual systems or sites. The data should be analysed on a regular basis and the Excel Workbook helps by holding the records for each system on separate tabs and generating a summary report for all of the systems for use in management reporting and review.

The cost of the lost refrigerant generally represents a small proportion of the total running cost, even though the resulting environmental impact is high, but the actual costs of replacing refrigerant will normally be significantly higher due to service engineer site visit cost, as well as any consequential costs due to system downtime. The carbon emissions and cost calculator (Figure 4-13) uses refrigerant GWP, cost and labour charge defaults to estimate the environmental and financial impact of refrigerant leakage, from historical records of refrigerant additions.

Figure 4-13 Carbon emissions and financial cost calculator

All the materials and tools were made available as free downloads from a dedicated website at

www.realzero.org.uk. They have since been revised as part of the REAL Skills Europe project

and updated versions are available from the REAL Skills Europe project website. The REAL Skills Europe project is described in Appendix D.

As a 12 month follow up to the REAL Zero site surveys and analysis, further data were obtained from 26 of the 81 systems and used to estimate the potential impact of the REAL Zero project if implemented more widely. For these systems, a net reduction in refrigerant leakage of 4,905 kg refrigerant was reported for 2009/2010 compared with 2008/2009. This represented a

direct saving of 7,979 tonnes of carbon dioxide equivalent (tCO2e), a reduction of more than 43% compared with the previous 12 month period.

The leakage rates across their entire refrigeration estate for two supermarkets that have adopted REAL Zero principles are shown in Figure 4-14. Their annual leak rates have continued to reduce and are now significantly below 10%. New systems employing best practice in design, build and operation can achieve annual leak rates of 1%.

Figure 4-14. UK supermarket refrigerant leak rate improvement for two companies: 2000 to 2010