**3. Methods**

This study aims to create a comprehensive integrated methodological approach to support the UK's net zero target, which sets ambitious requirements in terms of decarbonising space heating. The method consists of the integration of four different models that inform each other (Figure 1):


**Figure 1.** A schematic diagram of the proposed integrated approach.

First, individual energy, environmental, and economic results of different archetypes are calculated. Then, cumulative results for Orkney are calculated by multiplying the individual results by the number of archetypes and heating types for the baseline model based on BSM results. Finally, a scenario analysis is conducted to compare overall results for the current situation with future scenarios to analyse energy, environmental, and financial savings. In this study, only an ASHP is considered for the analysis for simplicity. However, the study can be extended to other heat pump typologies and heating technologies. Two scenarios have been developed for the year 2050 (Section 3.5).
