Natural refrigerants: R-290, R-744 and ammonia compared

While the F-gas phase-down puts the availability and price of synthetic refrigerants under pressure, three old acquaintances are moving back to the centre of the market: propane (R-290), CO₂ (R-744) and ammonia (R-717). Their common feature: GWP ≤ 5, so no quota, no future ban, no STEK emissions pressure. Their difference: very different installation requirements. Below is what each type is meant for and when you might consider it.

What are "natural refrigerants"?

A [natural refrigerant](/kennisbank/begrippen#natuurlijk-koudemiddel) is a substance that also occurs in nature and doesn't need to be synthetically produced: hydrocarbons (propane, isobutane), carbon dioxide, ammonia and water. Unlike HFCs and HFOs, they fall outside the F-gas Regulation — a leak from the installation doesn't count against the company quota and doesn't count towards the STEK emissions calculation.

The downside: each has its own safety challenge. Propane burns, CO₂ operates at pressure levels of 60-130 bar, ammonia is toxic and mildly flammable.

R-290 — propane for heat pumps

Safety class A3 (flammable, non-toxic), GWP 3. R-290 is on the rise as a refrigerant for residential and small commercial heat pumps, especially outdoor units.

What makes it strong:

• Thermodynamically excellent: in many designs comparable to or better than R-32 on COP.
• GWP of 3 → one of the lowest of all practical refrigerants, after CO₂.
• Availability is guaranteed; no quota, no long-term supplier uncertainty.

What needs attention:

• A3 means a large flammability margin. Legal limits on charge per room are considerably stricter than for A2L (R-32). A typical residential heat pump therefore needs to be sited outdoors; indoor installations require substantial extra ventilation or detection provisions.
• Service and maintenance require spark-free tools and awareness of ignition sources.
• The F-gas company certificate is not required for R-290 (it's not an F-gas), but sensible contractors maintain the same administrative quality and BRL 200 discipline.

For residential heat pumps where the installer can site the outdoor unit on a free-standing wall, R-290 is a clearly growing choice in 2026 — partly because it sits well below the future 150-GWP limit that R-32 (GWP 675) and R-454B (466) may eventually run into.

R-744 — CO₂ for heat pumps and commercial refrigeration

Safety class A1 (non-flammable, non-toxic), GWP 1. R-744 is technically the "cleanest" refrigerant — carbon dioxide is literally the reference value for climate impact.

Applications:

• Domestic hot water heat pumps (the high delivery temperature CO₂ cycles achieve fits well with the 60-70°C hot water requirement).
• Supermarkets — booster systems for deep-freeze + refrigeration on a single central R-744 circuit have become the market standard in new builds.
• Industrial cold rooms and freezer rooms.

What the challenge is:

• Operating pressure is considerably higher than for HFCs. An R-744 circuit routinely operates above 80 bar and can reach above 100 bar under transcritical conditions. Components, pipework and couplings need to be specified for that level.
• Trans- vs subcritical cycles: CO₂ has a critical point around 31°C; in warmer climates the circuit switches to transcritical, which requires a different design than a traditional evaporator-condenser system.
• Installer knowledge: R-744 technician training is not a given part of a standard refrigeration course; a specialist certificate is recommended.

In the commercial segment, R-744 is by now a mature technology; for homes it mainly appears via domestic hot water heat pumps.

R-717 — ammonia for industry

Safety class B2L (toxic, mildly flammable), GWP 0. Ammonia is the longest-serving industrial refrigerant — used in large-scale refrigeration and freezing technology for more than a century.

Where ammonia is used:

• Large freezer storage (logistics, the food industry).
• Ice rinks and large refrigeration installations.
• Industrial process applications.

Why never for homes:

• Toxicity: a leak of more than a few kilos of ammonia in an enclosed space is a medical emergency. Workers operate with personal gas detection and trained emergency procedures.
• Measures: double containment, sniffer systems, evacuation plans — investments that are affordable in an industrial context but don't scale down to a residential heat pump.

For a local installation company, R-717 is generally out of scope. It's mainly relevant to recognise on a different track: when taking on an industrial customer with an ammonia installation, separate certifications and risk management apply.

Decision table: which natural refrigerant, when?

General orientation, not tailored advice:

• Residential heat pump, outdoor unit: R-290 (propane).
• Domestic hot water heat pump: R-744 (CO₂) for applications needing 60+°C.
• Commercial refrigeration/freezing (supermarket, distribution): R-744 (CO₂) booster system.
• Industrial scale (>500 kW, freezer storage): R-717 (ammonia), carried out by specialised companies.
• Smaller comfort air conditioning inside a home: for now still HFC/HFO (R-32 or R-454B); R-290 is growing in that segment but the A3 requirements make indoor siting difficult.

What this means for installer administration

Three practical implications:

• The GWP balance gets cleaner. With designs using R-290 or R-744, the logbook-obligation check rarely comes out positive — a typical R-290 charge of a few hundred grams stays miles below the 5-tonne threshold.
• Leak-check frequency often drops away. Below the 5-tonne threshold, the legal leak-check obligation doesn't apply — but manufacturer maintenance schedules remain leading for warranty purposes.
• STEK reporting simplifies. No F-gas in the installation = no emissions contribution to the annual STEK statement.

What stays: the discipline around work orders, certificates and installation history. Golden rule: a BRL 100 company documents every installation with the same precision, regardless of whether the refrigerant is an F-gas or a natural type.

How Koldwerk works with this

For every installation you select the refrigerant from a fixed list that treats natural types (R-290, R-744) the same as HFCs: the matching GWP (3 or 1) automatically ensures the CO₂-equivalent calculation in the installation management module doesn't create a leak-check cycle as long as you stay below the threshold. The same refrigerant administration works for R-290 — handy if you maintain a mixed installation portfolio and don't want to split the logic. Pricing is on /prijzen.

Further reading

• GWP values of refrigerants — full table with threshold context.
• R-32 vs R-410A vs R-454B — the synthetic counterparts.
• F-gas quota 2027: prepare your business — why natural refrigerants become more important in 2027-2030.
• F-gas leak checks: how often are they mandatory? — when natural types stay below the threshold.

Disclaimer: natural refrigerants each require their own safety approach (A3 flammable, B2L toxic, high operating pressures for R-744). This article is a general orientation — for a specific choice or installation, consult the manufacturer's documentation, ATEX requirements (for A3) and the Dutch Besluit activiteiten leefomgeving (Bal) with the Omgevingsregeling, since 1 January 2024 the successor to the Activiteitenregeling milieubeheer.