Ammonia or HFC refrigeration for a new cold storage: what is the carbon difference?

Ammonia leaks add no CO2e, while every kilogram of R-404A that leaks adds about 4.7 tonnes of CO2e. A 500 kg R-404A charge losing 10% a year adds about 236 tonnes of CO2e a year. Electricity is the other half, so compare both systems' annual kWh before deciding.

Where the carbon difference comes from

• Leaks: refrigerant lost through joints, valves and servicing is a direct Scope 1 emission, counted as kilograms lost x the gas's GWP.
• Electricity: compressors, fans and pumps run all year, and their kWh are Scope 2 at 0.710 kg CO2 per kWh on the Indian grid.
• Ammonia (R-717) is not a Kyoto gas and IPCC AR6 gives it no GWP, so its leaks count as zero CO2e. The choice then turns on electricity.

How the R-404A figure is worked out

R-404A is a blend, so its GWP is the mass-weighted sum of its parts, using IPCC AR6 100-year values: 44% HFC-125 at 3,740, 52% HFC-143a at 5,810 and 4% HFC-134a at 1,530. That gives 0.44 x 3,740 + 0.52 x 5,810 + 0.04 x 1,530 = 1,645.6 + 3,021.2 + 61.2 = 4,728. Lower-GWP HFC and HFO blends sold as R-404A replacements cut this, but not to zero; work out their GWP the same way from the supplier's composition.

Why the HFC phase-down matters for a 20-year asset

Under the Kigali Amendment India, an Article 5 Group 2 country, freezes HFC consumption in 2028 and then steps it down until 2047, when it reaches 15% of the baseline. A cold store commissioned now will still need top-up gas in the 2040s, when far less HFC can be sold in India. Ammonia sits outside the phase-down. The full step-by-step schedule is on our Kigali page linked below.

How to compare two quotes fairly

Ammonia is toxic, so plant room design, trained operators and local safety approvals are part of the decision. They are outside this carbon comparison.

1. Ask each vendor for the refrigerant, charge in kg and expected annual kWh at your design load and ambient temperature.
2. Estimate leaks as charge x an annual leak rate. Use your own service history if you have it; otherwise label it an estimate.
3. Add pump energy for any glycol or CO2 secondary loop used with ammonia; it is part of the ammonia system's kWh.
4. Compare total annual CO2e: leak kg x GWP plus kWh x 0.710.

Worked example: 500 kg R-404A charge against ammonia

• R-404A charge 500 kg, annual leak 10% (illustrative) = 50 kg
• Leak emissions: 50 x 4,728 = 236,400 kg, about 236.4 t CO2e a year
• Electricity, both systems assumed at 1,000,000 kWh a year: 1,000,000 x 0.710 = 710,000 kg, 710 t CO2
• HFC system: 236.4 + 710 = 946.4 t CO2e a year; ammonia system: 710 t
• If the ammonia system used 10% more electricity: 1,100,000 x 0.710 = 781 t, still 165.4 t a year lower
• Break-even: the ammonia system could use 236,400 / 0.710 = 332,958 kWh more a year, about 33% more here, before the HFC system has the lower total

Leak rate and electricity use are assumptions for the arithmetic. Industrial refrigeration leak rates vary widely with design and maintenance; use your vendors' figures.

What Senseible does here

Senseible turns a refrigerant top-up invoice into Scope 1 CO2e once the gas and the kilograms charged are given, and counts the cold store's grid power in Scope 2 at 0.710 kg CO2 per kWh, so after commissioning you can see whether leaks or electricity drive the footprint. The comparison before purchase uses your vendors' own figures.

• Low GWP refrigerant for a new chiller
• Refrigerant leaks in cold chain footprints
• Cold storage electricity per tonne
• India's HFC phase-down schedule

Sources: IPCC AR6 WG1, Chapter 7 Supplementary Material, Table 7.SM.7 (GWP100), Kigali Amendment schedule for India and India Cooling Action Plan (MoEFCC, 2019), Ozone Cell

Last reviewed 2026-10-17. R-404A GWP is computed from AR6 component values; recheck if a buyer or programme requires AR5 values.