Compressing heat pumps into urban spaces

With urban population density remaining high, heat pump technology is increasingly seen as a solution for low-carbon heat. However, as emissions legislation continually tightens, and space remains at a premium, ensuring these installations are scalable and compatible with low global warming potential (GWP) refrigerants is vital, says Nicol Low, COO at Vert Technologies


t cannot be denied that the Government’s net zero targets are ambitious, and ambitious aims require ambitious actions. Indeed, since those sustainability

targets became law in 2019 on the recommendations of the Committee on Climate Change (CCC), momentum has continued to gather across sectors, including residential construction.

Heat pump popularity

Over 18 months following the implementation of net zero legislation, heat pumps technology has become increasingly identified as a key accelerator for the UK’s decarbonisation efforts. For example, the Prime Minister announced that the Government would set targets to install 600,000 heat pumps on an annual basis by 2028 as part of its 10-point plan for a green industrial revolution. Though this represents a marked increase on the 25,000 currently installed yearly, the CCC actually advocated going further, setting a potential target of one million heat pump installations each year by 2030 in their Sixth Carbon Budget. Regardless of this variation, it is clear that this heating technology is expected to play a big role in decarbonising new and existing housing stock.

Ongoing implementation

According to Government BEIS figures in 2018, referenced in the CCC’s net zero recommendations, approximately 17 per cent of the UK’s total emissions come from heating buildings. The failure to adequately tackle this figure was identified as a key contributor to the country lagging behind on the Government’s previous Climate Change Act 2008 targets, with homes comprising 77 per cent of this overall figure.

Consequently, the pollutive potential of residential

properties using less sustainable heating is clear. Yet with the need to decarbonise the UK’s homes becoming increasingly pressing – as shown with the Future Homes Standard outlawing gas boilers in new builds from 2025 – viable solutions like heat pumps will need to be rolled out quickly if we are to hit ongoing government installation and emission targets. Considering further World Bank data stating that

over 83% of the UK’s population lived in urban areas in 2019, it is also clear that decarbonisation efforts will primarily occur in places of high population density. Due to this, ensuring heat pumps could be scaled down without a loss in performance or sustainability is of vital importance if we are to hit government installation and emission targets. More specifically, ensuring the technology remains modular and efficient while using low-GWP refrigerants will be key to its long-term viability as an eco-friendly solution.

Conical rotary compressors

The compressor is a core component of the heat pump, circulating and pressurising the refrigerant heat transfer medium and enabling the heat- producing condensation and evaporation processes key to producing heat. Traditional screw, reciprocating piston and scroll compressor designs have typically used high-GWP hydrofluorocarbons (HFCs). A commonly used working fluid in a current heat

pump, R-410A has a global warming potential of 2,088, making it 2,088 times worse than CO2. It is contained within the heat pump itself and though the refrigerant is not emitted during normal operation, decommissioning or leaking systems pose an environmental threat, made all the worse with the large number of systems planned in the future. Lower

GWP refrigerants are available, with CO2 being a great future candidate with a GWP of just 1, but there are technical challenges to their adoption. The fact that low-GWP media require high absolute

pressures and pressure ratios for best performance can lead to long-term complications for traditional compressor technologies. To achieve the pressures and ratios required, traditional compressor types may need to be daisy-chained at added CapEx cost and inefficiency, and require larger installations in crowded areas where space is at a premium. Conical rotary compressor (CRC) technology, by

contrast, allows for a scalable heat pump that can use low-GWP refrigerants. CRCs differ from previous compressors that use rotating screws placed side- by-side, instead using rotors that turn in the same direction at different speeds to compress heating mediums as they travel down the conical screw.


The technology can achieve a 25:1 pressure ratio using an air medium, with the ability to change rotor geometry to ensure performant heat pumps regardless of refrigerant, media, application, and heating demand throughout the day. Consequently, it can enable continued efficiency and safeguard against rising costs while remaining scalable, which is key to heat pump rollout in urban environments. In conclusion, heat pumps are indeed set to play a

large role in the nation’s emission-lowering efforts, and their impact will most clearly be seen in crowded city centre areas. However, for the best possible effect, both now and in the future, it is key that installers opt for pumps with compressors best-suited to the ongoing HFC phaseout. With solutions like CRC technology, this futureproofing is possible in a scalable solution.


April 2021


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