Produced in Association with


SERIES 23 / Module 03 Heat Pumps


providing a stable year-round heat source. GSHPs can be further classified


by the heat collection system. These can be: ● Closed loop, horizontal systems.


A heat exchange fluid is circulated through pipes laid horizontally at a depth of 1-2m. The collector system requires a large area of ground, up to 85m² per kW of heating. Looked at another way, the system needs between 10 and 50m of pipe per kW – so a 20kW unit could require up to 1km of piping. The actual length will depend on the specific installation. Research is being undertaken on the use of flat plate collectors for GSHPs. ● Closed loop, vertical. As with the


horizontal system, heat exchange fluid is circulated, but in this case through pipes laid in boreholes that range in depth between 50-100m. Each borehole would support about 3-6kW of heating, with a spacing of 7-10 metres. Site access for the drilling rig needs to be considered. ● Open loop – this system takes


advantage of ground water extracted from and returned to a suitable underground body of water. Can also provide cooling in summer. More efficient than closed loop systems – but extensive site investigation required and not suitable for all sites. Environment Agency approval may be required.


Waste heat recovery heat pumps A heat pump can be used to recover waste heat in manufacturing/process industries. This can be attractive where the waste heat is ‘low grade’. In these situations, the waste heat can provide a ‘stable’ source of heat. Solutions could be air to air; water to water; water to air. It is essential that the process


producing the waste heat is fully optimised before considering the heat pump. It is unlikely there is a stock heat pump solution for waste heat recovery and a specialist provider will need to be involved from the initial stages.


Dual source heat pumps The dual source heat pump (DSHP) takes advantage of either air or ground heat sources, depending on operating and climatic conditions. It can select the most favourable heat source or heat sink (for heating or cooling, respectively). In winter it can provide hot water for heating


Produced in Association with


Heat Output Air/Water


Heat Source Compressor Air/Water/Ground


Condenser Electrical Power


Evaporator


Indoor


Expansion Valve


Outdoor Typical Heat Pump Cycle


buildings, using either the air or the ground as heat sources. Alternatively, in summer, it uses the air or ground as a heat sink to provide cooling. The unit can also provide domestic hot water, which in summer it can generate by using the system’s condensing waste heat.


Transcritical heat pumps Transcritical heat pumps use carbon dioxide (CO₂ - also known as R744). Due to the properties of CO₂ transcritical systems can operate with a much larger temperature difference – typically having a return temperature of 30ºC and a flow temperature in excess of 80ºC.


Hybrid systems A hybrid system is a combination of a heat pump matched, typically, with a gas fired boiler. A hybrid system can supply heat at a higher temperature and as such is a possible candidate for retrofit systems. However, as the system does use gas, the carbon benefit will be less than a ‘pure’ heat pump running on renewable energy.


Greenhouse gas emissions It is worth reviewing heating as part of the UK’s GHG emissions. It is estimated that heating accounts for about 37% of total carbon emissions. This breaks down to around 17% for space heating; 4% for hot water; 2% for cooking and 14% for industrial processes.


There are three technologies


that are considered viable for the replacement of fossil fuel fired heating installations:


● heat pumps


● alternative gases (hydrogen & biomethane) ● heat networks


According to the IEA heat pumps could satisfy 90% of the global heating needs with a lower carbon footprint than gas-fired condensing boilers. Heat pumps are widely used in some European countries for example, Norway (60% of homes) and Sweden (43% of homes), whilst in 2023 it was estimated that only 1% of UK homes had heat pumps. Heat pumps can provide an


alternative, low carbon heating solution that can be delivered unit by unit – without new infrastructure. However, to be a real low carbon solution heat pumps need to be powered by renewable energy. In part this will be achieved by ongoing grid decarbonisation. However, the starting point needs


to be improving building energy efficiency to first reduce heating demand. For efficient operation, heat pumps and emitters should be sized to match the heating demand of the building. Undersized heat pumps will not achieve the desired


building temperatures. Oversized heat pumps will operate at partial load, which reduces efficiency, although improved compressor technology has reduced this effect. Continuous low temperature operation is generally the most energy efficient way to use a heat pump, whereas most people use gas boilers on demand, so user behaviour needs to be addressed. New build provides the ideal


opportunity to optimise both building and systems. When looking at a new build in the domestic sector it is suggested that upgrading to Passivhaus standards would add between 5 and 10% to the build cost but deliver a 75% reduction in heating demand (source EST). Underfloor heating is ideal for heat pump technology as it is typically operated at a maximum of 35ºC. Warm air is also suitable – whilst quite common in the commercial and industrial sectors, it is not common in the UK residential sector. The replacement of gas and oil


boilers with heat pumps will reduce overall domestic energy consumption but as a result electricity consumption will increase significantly. In a scenario where 80-90% of households install heat pumps estimates suggest that annual electricity demand could increase by 25-50%, and peak demand by 50-100%, this will require a significant investment in electricity infrastructure to deliver more power, particularly during peak times.


24


EIBI | SEPTEMBER 2025


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44