Supermarket transcritical R744 pack sizing — start to spec
By DigiEntropy Engineering · 2026-02-08 · 7 min read
Transcritical CO2 has dominated new European supermarket refrigeration since ~2018. Pack sizing has its own conventions — booster vs flooded, parallel compression, ejectors, gas cooler approach. The Supermarket Refrigeration page walks through it.
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Every new commercial supermarket designed in the EU since the 2024 F-Gas Regulation tightening has been R744 transcritical. The architecture is well-understood (booster pack with MT + LT compressors sharing a gas cooler) but the sizing is non-trivial — you need to match MT load to MT compressors, LT load to LT compressors, gas cooler to combined heat rejection, and decide on parallel compression + ejector + heat reclaim before committing capex.
Supermarket Refrigeration walks the design from store-level cabinet loads to the final pack spec.
60-80 kW - MT load, mid-size store - 15-25 kW LT
A typical mid-size supermarket (2000 m² floor area, 400 m² refrigerated): 60-80 kW MT, 15-25 kW LT.
100 kW - booster up to this total - most installations
Booster: when to pick it, most installations under 100 kW total. Flooded (parallel): larger / energy-sensitive installations.
5-10 % - COP gain, parallel compression - pays back in 2-4 years
COP gain: typically 5-10 % at warm ambient (gas cooler outlet > 30 °C). Capex: one extra compressor + plumbing. Pays back in 2-4 years in southern Europe.
8-15 % - COP gain, ejectors - pays back in 3-6 years
COP gain: 8-15 % at warm ambient. Capex: substantial (ejector hardware + controls). Pays back in 3-6 years.
31.04 °C - CO2 critical temperature - approach squeezed to 5-7 K
At warm ambient (> 30 °C), approach gets compressed into a 5-7 K window because the gas cooler outlet sits just above the critical temperature (31.04 °C).
60-90 °C - gas-cooler discharge - store heating, DHW, floor heating
Heat reclaim is the killer feature for R744 transcritical: the gas-cooler discharge runs at 60-90 °C, perfect for store heating, DHW, or floor heating.
80-100 % - store space heating offset - reclaim-equipped pack, in winter
A reclaim-equipped pack can offset 80-100 % of store space heating in winter.
280 - R744-qualified compressors - across 6 brands
Compressor Galaxy filtered to R744: about 280 R744-qualified compressors across 6 brands.
The MT vs LT load split
MT loads
- Vertical refrigerated cabinets (dairy, deli, produce): -8 to +4 °C cabinet, evaporator typically -10 °C
- Walk-in chillers (back-of-house): +2 °C room, evaporator typically -5 °C
- Beverage coolers, sushi displays: similar to vertical cabinets
LT loads
- Frozen vertical cabinets: -22 to -18 °C, evaporator typically -32 °C
- Walk-in freezers: -22 to -18 °C, evaporator typically -28 °C
- Ice cream cabinets (some plug-in, some on the LT rack): -25 to -22 °C cabinet
A typical mid-size supermarket (2000 m² floor area, 400 m² refrigerated): 60-80 kW MT, 15-25 kW LT.
Booster vs flooded
The two dominant transcritical R744 architectures:
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