4.3.1. Energy Savings

Current energy results (supply and demand) and proposed scenarios are calculated at individual archetype and Orkney levels. The unrefurbished houses have the highest demand as expected, where detached houses have the highest demand among archetypes with an average of 16,591 kWh because of the larger gross floor area and exposed walls to outside conditions (Figure 8). However, it also varies depending on the building specifications. The highest demand occurs in an unrefurbished detached house with 21,774 kWh. This could be reduced to 16,525 kWh if the building is refurbished or to 11,473 kWh if the house has stricter EEI measures.

**Figure 8.** Energy demand results (**left**) and proposed energy supply (**right**) by house archetypes for heat pump uptake scenarios.

The demand figures and main heating fuel type results in the EPC dataset are integrated with BSM to illustrate overall results for Orkney (Figure 9). Overall domestic demand occurs at 186.4 GWh whereas supply stands at 192.0 GWh. While calculating the supply, 2.65 is used as an average seasonal performance factor (SPF) value for the current heat pumps as the field trial shows [62]. The majority of supply is currently provided by electricity and oil with 84.2 GWh and 83.3 GWh respectively. However, heat pump model scenario results show that supply could be reduced to 67.0 GWh with the RE scenario by replacing 75% of the electric heaters and boilers with ASHPs. The supply could even be reduced to 34.4 GWh if all heating types are changed to ASHPs with the CE scenario. It is

also important to recall that the energy efficiency of housing stock also plays an important role because unrefurbished houses require higher supply values. Therefore, RE and CE scenarios consider EEI measures taken at different rates explained in the methodology section.

**Figure 9.** Comparison of energy demand and supply for house archetypes with heat pump uptake scenarios by fuel type.

RE results show that if EEI measures are taken, energy demand will decrease to 173.6 GWh and supply will be reduced to 67.0 GWh. This accounts for a 7% decrease in demand and a 65% decrease in supply respectively. The demand figures also include the new housing stock by 2050, which is around 19% of the existing houses. However, energy efficiency improvements help to decrease the total demand.

CE scenario results show that more strict efficiency standards could provide a 16% reduction in demand even though the total number of dwellings is increased. Higher EEI measures create less energy demand for the entire housing stock. Energy supply is expected to decrease by 82% (to 34.4 GWh) by replacing all heating technologies with ASHPs. The main reason for a higher reduction in energy supply is that heat pumps are significantly more efficient than other heating technologies. Therefore, the reduction in supply is significantly higher than demand in the CE scenario.
