182 (between the EEB and the heat pump) would be needed in order to avoid too high a fluid entering temperature at the evaporator.
Figure 5. Sankey diagram of the EEB energy fluxes for the whole period of analysis
3.2. Discussion on the potential contribution to the sustainable development goals (SDGs)
From the experimental analysis of this research, it was shown that although more research is needed to improve the system configuration of the shallow GSHP technology, there is a high potential for this technology to be widely used in the domestic heating sector. First, it was shown that the shallow systems are a configuration that indeed can cover the heating demands of a low-energy home (where the peak heating load is typically bellow 20 W/m2). Likewise, the cost and speed of installation of shallow geothermal boreholes are very low compared to conventional GSHP systems, as the drilling process would not require the use of robust machinery. Finally, the fact that renewable energy technologies are becoming much more affordable allows shallow SAGSHP technology to be competitive for the domestic sector. Hence, the option of using this technology could be very attractive for the building sector.
On the other hand, considering that this competitive system has an average SPF of 2.5 over the year, this would mean that the required input energy (electricity) would be 40% of the conventional electricity radiators to cover the same demand. However, when compared to gas heating and considering that in the UK the cost per kWh of gas is around 25% of the electricity price, running the shallow SAGSHP would cost 38% more. However, different electricity tariffs could be used, which means that an HP could run overnight and store hot water for space heating and the price could be highly reduced. To do this, a smart control strategy would be required.
Considering that only in England, 160000 new homes are built every year and that a low energy design is being required over time, there is high potential to make a difference in developing the market of clean and affordable energy and make a real contribution to the SDG 7.
4.
Conclusions
The objective of this paper is to present the experimental results of a solar assisted ground source heat pump (SAGSHP) that uses a shallow (1.5 m peep) vertical ground heat exchanger and the potential of using this technology to contribute in reaching the sustainable development goal (SDG) 7 which is to reach clean al affordable energy by 2030. It was evidenced that a shallow geothermal heat exchanger could be an affordable option for covering the heating demands of low-energy homes. This technology can be even more effective when using in combination with solar energy for short-term and long-term energy storage. The average monthly seasonal
183 performance factor of this system was above 2.3, which is competitive compared to conventional air source heat pumps. It was also highlighted that this configuration could be improved in terms of control strategy and the use of intermediate heat storage system to enhance the whole annual system’s performance. The potential applicability of this system in England is very high as it is much more effective than conventional electric heating and could compete with gas heating by an appropriate control and storage strategy. If this technology could be applied in a percentage of the new homes’ projects, a significant contribution to the SDG7 could be reached.
5.
Acknowledgements
The authors of this research acknowledge De Montfort University, Caplin Homes UK and Vaillant UK for their contribution in setting up the experimental system.
6.
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