REFRIGERANTS Figure 1
climate the reduction in emissions is just 5% with a 19% higher 10-yr LCC compared to the baseline technology.
Relative to the other technologies the secondary loop technologies performed in much the same way as in the larger format store with emissions reduced by 1-8% with an increase of 13-23% 10-yr LCC compared to the baseline technology making them the highest 10-yr LCC options at the moderate climate conditions. The secondary loop technologies also have the highest Capex requirements of all the technologies.
The lowest climate change emissions were once again achieved when using the low GWP mildly flammable Opteon XL refrigerant options with emission reductions of 16-20% compared to the baseline technology. The 10-yr LCC values were also the lowest of all the alternative technologies at both climates ranging from 9-19% lower than the other technologies.
Figure 2
Whilst the refrigerant GWP is an important factor this study has demonstrated it is far from the only consideration and using refrigerants with GWPs <10 does not necessarily improve the climate change emissions produced during the operation of the system.
At the beginning of this article a wish list of selection criteria from a leading retailer were given.
Compared to the current <1500 GWP refrigerant option, Opteon XL20 and Opteon XL40: Match Cooling Performance Exceed Energy Performance Match System Uptime (minimise risk to trade) Match Total Cost of Ownership Match Ease of Installation and Maintenance Reduces Total CO2
e Emissions by up to 17% At the Lowest Life Cycle Cost of the alternative technologies.
Standard Supermarket
Although air conditioning integrals require a low capex, they are also by far the most expensive and worst emitting options of the technologies considered. Making the integrals water cooled does improve the emissions and LCC, but not beyond the baseline Opteon XP40 technology and would have to be questioned as a serious contender as a future replacement technology.
Transcritical R744 booster technology is often cited by NGOs as a preferred choice but it is not best suited to warmer climates and this can be seen in Figure 1, but what is probably more surprising is that even in the more moderate climate of Leicester the Transcritical R744 Booster technology only delivers 4% lower emissions than the baseline technology at an increased 10-yr LCC of 21%. The technologies involving secondary loops deliver emissions 2-9% lower than the baseline technology but with a 12-22% higher 10-yr LCC. The Largest reduction in emissions is achieved when using the Low GWP mildly flammable Opteon XL refrigerants (16-20%) which also have the lowest 10-yr LCC of all the low GWP alternative technologies (8% -22% lower).
Small Supermarket
In this smaller format the AC and WC are no longer the highest 10-yr LCC options but are still the worst options in terms of emissions and do not show lower total emissions compared to the baseline Opteon XP40 technology. On this basis the use of AC or WC Integrals does not appear to be a credible future alternative technology for this size of store.
As previously mentioned, the Transcritical R744 Booster technology was not expected to fare well in the warmer Sevilla climate and, as can be seen in Figure 3, this was confirmed having the highest emissions of the non-integral options and the highest 10-yr LCC of all the technologies. Even at the moderate Leicester
Figure 4
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Figure 3
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