*3.5. Proposed Scenarios*

Two scenarios have been developed for the year 2050. Only the case of ASHP is considered for the analysis for simplicity. However, the study can be extended to other heat pump typologies and heating technologies.

Baseline Scenario: It represents the current situation at Orkney. The number of heat pumps deployed on the island is around 1050 (representing one-tenth of total dwellings). The number of dwellings and fuel types of house archetypes and specifications for the scenarios are provided in Figure 2.

Resource Efficiency (RE) Scenario: A reduction in energy demand is expected but this decrease is lower than the CE scenario. EEI applications are limited. RE scenario assumes that 75% of fossil fuel heating technologies will be replaced with heat pumps. EEI measures are taken for 75% of unrefurbished and 25% of refurbished houses. Half of the new dwellings constructed before 2050 are assumed to be in the new building category and those remaining are in the refurbished category, all of which use heat pumps for space heating.

Circular Economy (CE) Scenario: High technology development and high consumer engagement are supported by policies. Therefore, more efficient houses and low-carbon technologies portend a reduction in energy demand. The uptake of heat pumps reaches 100% to achieve UK's Net Zero target. CE scenario assumes more ambitious numbers to achieve UK's Net Zero target. All of the heating technologies will be replaced by heat pumps in this scenario. The majority of the new dwellings (75%) constructed before 2050 will be in the new building category and the remaining will be in the refurbished category. CE scenario assumes higher EEI measures taken with 100% heat pump uptake

Note: RE and CE scenarios expect an increase of around 2000 in the total number of dwellings (from 11,227 in the baseline model to 13,313 in the year 2050) in line with the historical trend.

**Figure 2.** Number of dwellings and fuel types by house archetypes and specifications for baseline and future scenarios.
