BSEE
Recent Government announcements have underlined heat pump technology’s status as a potenal gamechanger when it comes to construcng sustainably heated building stock. If the UK is to hit ambious emissions and installaon rollout targets, selecng heat pumps that use scalable and highperforming compressor technology suitable for refrigerants with low global warming potenal will be key, says Nicol Low, COO at Vert Technologies.
T
he Government’s 2019 decision to legally commit to net zero carbon emissions by 2050 continues to have a massive impact on all UK sectors, not least building and construction. Indeed, it would not be an
exaggeration to say that even almost two years after this pledge, specifiers, contractors and the wider industry continue to experience great upheaval.
One area impacted is heating, where a wave of technological innovation has been sparked by the need to reduce carbon emissions while still efficiently keeping properties warm. The need for sustainable heating solutions has been further exacerbated by legislation such as the Future Homes Standard, which would ban gas boilers in new builds by 2025. Though this represents a major, necessary step to reducing the UK’s reliance on fossil fuel heating, it makes finding alternative, greener solutions a matter of urgency. Faced with this challenge, the UK Government has identified heat pump technology as a potential way forward. This was reflected in a number of announcements made at the end of 2020, including a pledge to implement 600,000 heat pump installations per year by 2028, made as part of the Prime Minister’s Ten Point Plan for a Green Industrial Revolution. While this is already a marked increase on the 25,000 currently being installed annually, other organisations are arguing this might not be ambitious enough. Specifically, the Committee on Climate Change – the influential body whose recommendations led to the adoption of the original 2050 net zero emissions legislation – went further than this in their Sixth Carbon Budget in December, advocating for one million heat pumps to be installed by 2030. Considering these announcements, alongside a Government Energy White Paper published in the same month which highlighted the efficacy of heat pump technology in tackling heating-based emissions, it is clear great change is afoot in the heating arena, and building professionals must be aware of it.
District Heang Schemes One such way heat pumps are being introduced
into the country’s heating infrastructure is via district heating systems. Applicable for residential and commercial developments, district heating systems provide multiple buildings with heating and hot water via a network of pre-insulated pipes. The majority of UK district heating schemes are of the third generation, which uses a gas boiler or gas CHP system as a centralised source, circulating water at a 70-95oC flow temperature. However, thanks to continued technological innovation and tightening environmental legislation, these schemes are gradually falling out of favour, with fourth generation systems now preferred. These schemes, through which water circulates at 50-60oC, have been designed with renewable energy sources in mind, such as a large, singular heat pump.
HEAT PUMPS
Scalable and Sustainable Compressors for the Heat Pump Revolution
Due to this, they represent a more eco-friendly solution than fossil fuel-powered schemes and individual gas boilers.
Yet the pressing need to further decarbonise national heating infrastructure in line with Government plans, and the emphasis placed on heat pump technology as integral to this effort, has led to further innovation in the district heating space.
One such result of this ongoing effort to develop more efficient and sustainable technologies is fifth-generation heat networks, or so-called ambient loops. These schemes – which are already being installed – allow a flow temperature of 10-30oC, resulting in greater overall efficiency. Crucially, fifth-generation networks eschew the large, centralised pump designs in favour of individual heat pumps that boost temperatures to suit occupant demand, resulting in an eco-friendly system that further reduces heat losses.
Individual heat pumps Fifth-generation schemes will clearly be key to
ensuring we remain on track with net zero targets, and fulfil the Government’s ambitious heat pump installation plan. However, practical concerns still remain with the wider-scale adoption of this technology. Chief among these issues is ensuring that existing heat pump technology can be scaled down while remaining efficient and futureproofed against ever-tightening environmental legislation.
This combination of sustainability and scalability is absolutely crucial. In order for heat pumps to be a viable, decarbonising solution on the large scale the Government is projecting, they must remain efficient even in ever-smaller models, and continue assisting in the country’s transition to a net zero future. Ensuring this technology can operate at peak performance while using low-GWP refrigerants in place is therefore of vital importance, and key to this will be compressor design.
Conical rotary compressor technology
A core component of a heat pump unit, the compressor, pressurises and circulates the heat transfer medium, or refrigerant, through the system, facilitating the evaporation and condensing processes that heat the property. Traditional scroll, screw and reciprocating piston compressor designs have previously used hydrofluorocarbons (HFCs) with high GWP ratings as refrigerants, but a wider national effort to reduce HFC use by 79 per cent by 2030 has seen
14 BUILDING SERVICES & ENVIRONMENTAL ENGINEER MARCH 2021
such media increasingly replaced with low-GWP, natural alternatives such as ammonia and CO2. In turn, this has led to challenges for traditional compressor technologies, as these environmentally friendly alternatives require high pressure ratios and absolute pressures to ensure best performance. Consequently, this could impact long-term heat pump performance and lead to a scenario where these types of compressor need to be daisy-chained to meet required pressure ratios and absolute pressures. This would add further CapEx costs, size and inefficiency to existing systems, and result in a situation where manufacturers need to choose between performance and sustainability. Conical rotary compressor (CRC) technology could provide a way of avoiding this choice, creating a heat pump that can be scaled down and use low-GWP refrigerants.
Developed by Vert Technologies, CRCs differ from alternative compressors that use rotating screws that are 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.
The HFC phaseout
Most importantly, this adaptability means heat pumps can be futureproofed against the HFC phase-out and the possibility of significant added OpEx or CapEx in the near future. The technology is also scalable to fit smaller individual heat pumps without compromising on performance levels, making CRCs ideally suited to the wider heat pump rollout. As such, specifiers and contractors should consider heat pumps that make use of innovations like these if they are to future-proof new and existing projects, especially as the wider nation transitions to renewable energy sources and lower emissions.
In conclusion, building professionals and the construction industry as a whole are experiencing an ongoing shift to greener heating solutions, such as heat pumps. Yet in order to fully implement this potentially transformational technology, it is vital that the components that make up units are carefully considered for their scalability, and how this affects practical considerations such as performance and the potential for global warming. By opting for pumps that include CRC technology, concerns in these areas can be negated.
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