4.3.3. Heating Cost Savings

Energy modelling results illustrated that Comfy Heat and E12 tariffs have the optimum heating cost results. Therefore, the heating cost of house archetypes and specifications for Comfy Heat tariff are presented in Figure 12. E12 results are very similar to Comfy Heat tariffs and consequently omitted for simplicity. Detached houses have the highest heating cost with an average of £452 heating cost. Mid-terraced houses have 25% less heating cost on average, followed by end-terraced and semi-detached houses with 21% and 19% respectively. The main reason for this difference is that the demand varies based on gross floor areas and house archetypes.

**Figure 12.** Heating energy cost for heat pump uptake scenarios by house archetypes from Comfy Heat tariff.

House specification is also a significant factor to reduce heating costs. An unrefurbished detached house's energy cost could be as high as £592.4 for the entire year. Moreover, 48% of this cost comes from off-peak time electricity usage and 39% comes from peak time usage. Further, 13% is the standing charge which is the same for all house archetypes. When the energy efficiency of the house is improved to the refurbished category the total heating cost could be reduced to £450.3, and £313.1 with the new building category. The major reason for this reduction is that not only does the heating demand decrease with the help of EEI measures, but it also can help to shift much of the energy usage to off-peak time. Therefore, the share of peak time usage decreases to 30% and 14% in refurbished and

new building categories. Similar trends occur for the remaining house archetypes and the lowest heating cost occurs in a new building category end-terraced house with £281.

The total heating cost on the island is around £23.0 million and the majority of it comes from detached houses (Figure 13). Electricity is responsible for 76% of the total heating cost followed by oil, coal, and wood with 19%, 3%, and 3% respectively. RE scenario could help to reduce heating cost results to £8.4 million via replacing 75% of the heating technologies with heat pumps and EEI measures. The share of fossil fuels is reduced to 12% of the total heating cost in this scenario. CE scenario offers more reduction with more ambitious heat pump uptake and EEI targets in line with UK's net zero target. Even though only 25% of the heating technologies are not replaced in the RE scenario, replacing this stock could help to reduce the heating cost to £3.7 million which is less than half of the RE scenario. The main reason for this reduction is that the CE scenario not only offers to replace fossil fuels, but also an ambitious EEI scenario, so there will be no unrefurbished houses left and the majority of the houses are in the new building category with high-efficiency standards.

**Figure 13.** Heating energy cost of baseline model by archetypes and specifications and future scenarios.
