2-storey semi, solid brick 400mm with EXTERNAL insulation, 300mm loft,
suspended uninsulated ground floor, gas combi, double glazing (glazed_type 13).
Built in accredited Elmhurst RdSAP10: roof (U 0.14, 5.459 W/K) and windows
(15.32 x eff U 1.3258 = 20.311 W/K) match the engine EXACTLY; the
externally-insulated wall is engine U 0.29 vs Elmhurst 0.30, validating the
slice-5 external-insulation default (100mm added over solid brick); suspended
ground floor engine 0.68 vs Elmhurst 0.70. Elmhurst's overall SAP 67 is not
comparable (reused-assessment Standard-Combi keep-hot loss, a build artifact).
Engine 77 vs lodged 76 (within 1.24). Pinned to the observed 77.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
