Refrigerant choice and global warming potential in planning
Refrigerant is a greenhouse gas and systems leak. Which inputs a whole life carbon assessment must state, how safety classification drives plant location, and what a condition can secure.
Refrigerant choice belongs in a carbon assessment because the refrigerant itself is a greenhouse gas, and a heat pump or chiller loses some of its charge every year. A system charged with a fluid of global warming potential around 2,088 leaks a very different quantity of carbon dioxide equivalent from the same system charged with a fluid of potential around 675, and a fluid with a potential in single figures is a different order again.
That is separate from how efficiently the machine runs. Efficiency shows up in the electricity consumption. Refrigerant shows up in the use stage of a whole life carbon assessment, whatever the seasonal coefficient of performance says.
Why refrigerants appear in a carbon assessment
Whole life carbon methodology places refrigerant emissions in the use stage, alongside operational energy and water. The calculation is straightforward in structure: the charge in kilograms, multiplied by the global warming potential of the fluid, multiplied by an annual leakage rate, over the assumed service life, plus a loss at end of life.
Every one of those inputs is an assumption made by the designer, which is why the Whole Life Carbon Assessment has to state them rather than presenting a single figure. An assessment that reports a refrigerant contribution without naming the fluid, the charge and the leakage rate cannot be checked.
On an all electric scheme with air source heat pumps and comfort cooling, refrigerant is not a rounding error. It can be a visible share of use stage emissions, and it is one of the few items a design team can reduce by changing one line of a specification.
Global warming potential and leakage rates
Global warming potential values are published and widely used in the field. The hydrofluorocarbon blends that dominated air conditioning have high values, with R410A around 2,088. The single component replacements sit much lower, with R32 around 675. Natural and low potential fluids, including propane, carbon dioxide and ammonia, sit in single figures or lower.
Leakage rates are the contested input. They vary with system type, with joint count, with whether the circuit is factory sealed, and with the quality of maintenance over decades. Take the rate from the methodology being applied rather than assuming one, state it in the report, and run a sensitivity case, because a doubling of the assumed rate changes the answer more than most fabric measures do.
End of life recovery is the other assumption worth stating. A recovery rate applied without a maintenance and decommissioning commitment is optimistic, and reviewers notice.
The regulatory background and where it is heading
Great Britain operates a fluorinated gas regime based on the retained 2014 regulation, with a quota system that reduces the supply of hydrofluorocarbons measured in carbon dioxide equivalent, alongside leak checking, record keeping and recovery duties on operators. The European Union adopted a new regulation in 2024 and the Great Britain position has been under review, so check the current rules before describing what will be available in five years.
The direction is settled even where the detail is not. Quota reduction pushes prices up on high potential fluids and pushes manufacturers towards lower potential alternatives, and a building designed around a fluid that is being phased down carries a retrofit risk its owner may not have priced.
Low potential alternatives and their constraints
The reason everyone has not already moved is safety classification, and it is a real constraint rather than an excuse.
| Fluid group | Global warming potential | Main constraint |
|---|---|---|
| High potential HFC blends | High, in the thousands | Quota driven cost and phase down risk |
| Lower potential HFCs | Several hundred | Mildly flammable classification |
| Hydrofluoroolefins | Very low | Mildly flammable, cost, system sizing |
| Propane | Very low | Highly flammable, charge limits, plant location |
| Carbon dioxide | Negligible | High operating pressures, system design |
| Ammonia | Negligible | Toxicity, dedicated plant room, competence |
Charge limits for flammable refrigerants are set by the relevant safety standards and depend on room volume, ventilation and the location of the equipment. That converts a specification choice into a planning drawing question, because it determines whether plant can sit in a basement, on a roof or in an external enclosure.
One honest uncertainty is worth acknowledging. Published leakage rates are drawn from studies of installed systems whose maintenance regimes are unknown, and the spread between well maintained and neglected plant is very wide. A building with a funded maintenance contract and leak detection will do better than the assumption, and one without will do worse. That is an argument for securing maintenance rather than for arguing about the rate.
Safety, charge size and plant location
Plant location is where refrigerant policy meets the application. A propane system may need external siting with separation distances, ventilation openings and restricted access. An ammonia system needs a dedicated plant room with detection and a discharge route.
Those requirements affect the roof plan, the elevations, the acoustic assessment and the amenity case. Deciding the refrigerant strategy after the elevations are fixed is the sequence that produces a late redesign, and it is common.
Design the plant area for the safety case you intend to make, then confirm it. Reserved area, ventilation openings, separation distances and access route should all be on the submitted drawings rather than described in text.
An illustrative example shows the scale of the decision. A 90 unit block is designed with individual air source heat pumps and a small comfort cooling provision to communal areas. The first specification uses a high potential blend. Substituting a single component fluid with a potential roughly a third of it, with no change to the plant footprint or the efficiency figures, cuts the reported use stage refrigerant emissions by around two thirds across the assessment period. Nothing else about the building changes. This example is illustrative.
How it is reported in the energy statement
Set out, for each system: the fluid, its global warming potential and the source of that value, the charge in kilograms, the assumed annual leakage rate with its source, the assumed service life, the end of life recovery assumption, and the resulting carbon dioxide equivalent over the assessment period.
Then say what happens if the fluid changes at technical design stage. A one line sensitivity showing the effect of substituting the next most likely alternative is worth more to a reviewing officer than three pages of methodology. Carry the same numbers into the Energy Statement and the Sustainability Statement so that the documents agree.
Conditions that specify plant
Some authorities condition a maximum refrigerant global warming potential. It is a defensible planning requirement where local policy addresses carbon, and it is awkward to enforce because the fluid is chosen by a contractor long after permission.
A more workable pattern approves a plant schedule showing the system type, fluid and charge, requires installation in accordance with it, and requires a declaration of the installed fluid and charge before first occupation. That gives the authority something identifiable to check against, and it survives a change of supplier in a way that a bare numerical limit does not.
Where the scheme also turns on retaining or replacing an existing building, keep the refrigerant figures consistent with the assumptions used in the embodied carbon case for retrofit, because the two assessments share a service life and an end of life scenario.
This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Why does refrigerant appear in a whole life carbon assessment?
Because the fluid is itself a greenhouse gas and systems lose charge in service. Whole life carbon methodology places refrigerant emissions in the use stage, calculated from the charge, the global warming potential of the fluid, an annual leakage rate and the assumed service life, plus a loss at end of life.
What leakage rate should I assume?
Take it from the methodology being applied rather than assuming one, and state the source in the report. Rates vary with system type, joint count, whether the circuit is factory sealed and the quality of maintenance over decades. Run a sensitivity case, because doubling the rate changes the result more than most fabric measures do.
Why not simply specify a low potential refrigerant everywhere?
Safety classification. Propane is highly flammable, ammonia is toxic and carbon dioxide systems operate at high pressures. Charge limits under the relevant safety standards depend on room volume, ventilation and equipment location, which turns the refrigerant decision into a question about where plant can physically be sited.
Does refrigerant choice affect the planning drawings?
Yes. Flammable and toxic fluids carry siting, separation, ventilation and access requirements that determine whether plant can go in a basement, on a roof or in an external enclosure. Those requirements affect the roof plan, the elevations and the acoustic assessment, so decide the strategy before the elevations are fixed.
Can a council condition a maximum refrigerant potential?
It is defensible where local policy addresses carbon, but awkward to enforce because the fluid is chosen by a contractor long after permission. A plant schedule approved by condition, with a requirement to declare the installed fluid and charge before first occupation, gives the authority something identifiable to check against.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.