Figure A1
The flowchart is organized according to the legend categories shown at the bottom, which identify “Policy recommendations”, “Future research directions”, “Three elements of stepwise retrofitting and their interdependencies”, and “Real-time building performance data” for different colors. The description follows this order, starting with the central block labeled “Building Passport”, which features a home icon. The flow starts at “Building Passport”, which connects rightward to the three elements of stepwise retrofitting and their interdependencies oval “Sequencing”, proceeding top to bottom through “Step 1: Initial envelope improvements example Basic insulation Draft-proofing”, then “Step 2: Targeted envelopes upgrade examples Wall insulation Double glazing”, and finally “Step 3: Advanced technologies examples Efficient HVAC systems Renewables”. Another arrow from building passport leads downward tothree elements of stepwise retrofitting and their interdependencies box “Hybrid retrofit packages”, then to “Standardised common retrofit measures”, and further to “Complex measures that require detailed audits”, showing the structured progression of retrofit actions and evaluations. One more arrow from building passport leads downward to three elements of stepwise retrofitting and their interdependencies box “Timings”, then to “3-year spirit retrofit steps within each cycle”. Two boxes labeled “NATHERS assessments” and “National scorecard” lead to Complex measures that require detailed audits. The policy recommendation outputs labeled “Rebates”, “Discounts”, “Tax credits”, “Grants”, “Low interest loans”, and “Penalties”. An arrow from merges and leads to Standardised common retrofit measures. From rebates to low-interest loans are names Carrot-based policy program. Penalties is names Stick based policy programs. Moving next to the future research directions category, arrows extending left from the building passport connect to boxes labeled “Future research should evaluate different retrofit packages” includes “Technological challenges and potential benefits of retrofit methods”, “Fabric first approach to avoid lock-in effects”, and “Acceptable disruption level”. An arrow from the tree labels leads to hybrid retrofit packages. From timing an arrow that branches into two leads to “Start of the retrolifting process” and “10-year retrofit cycles”. Finally, under policy recommendations leftmost chain includes box labeled“Developing compliance cycles based on retrofit cycles to check the performance of buildings”, which encloses Future research directions box labeled “Developing a data-driven mechanism for timing retrofit cycles”. It further includes four boxes labeled “Real Estate Trends”, “The Pace of Climate Change”, “The Pace of Technological Advancements”, and“Degradation”, and an arrow from each box merges and leads to 10-year retrofit cycles. Future research directions box labeled “Developing a data-driven mechanism to identify when the house shows degrading its efficiency”. It further includes four boxes labeled “Occupancy Evolution”, “Degradation”, “The Pace of Climate Change”, and “Current Energy Efficiency Standard”, and an arrow from each box merges and leads to the start of the retrolifting process. Future research directions box labeled “Maia and others (2021) have developed a model to optimise intervals between retrofit steps based on homeowner affordability. Future research should test this model in different contexts under different socio-economic challenges”. It further includes three boxes labeled “Homeowner Preferences”, “Planned Replacement or Maintenance Routine”, and “Annual Income or Affordability”, and an arrow from each box merges and leads to the 3-year spirit retrofit steps within each cycle.A clear version of Figure 4