Model/docs/migrations/property-baseline-performance-table.md

property_baseline_performance table — FE-owned migration

Context: Slice 6 (Hestia-Homes/Model#1135) of the ara_first_run rebuild. The PropertyBaselineOrchestrator establishes a Property's Baseline Performance (ADR-0004) and persists it via a new PropertyBaselineRepository port. This is a brand-new table — no predecessor.

Per ADR-0004's amendment, the lodged/effective pair does not land on property_details_epc (which is being retired as too coupled to the legacy EPC-API schema). It lands here, as its own aggregate's table.

The SQLModel row is defined in infrastructure/postgres/ so the ephemeral-Postgres tests build it via SQLModel.metadata.create_all. The production migration is FE-owned (Drizzle ORM) — a straight lift-and-shift of the columns below.

property_baseline_performance — one row per Property

Column	Type	Notes
id	serial PK
property_id	int, FK → property.id, unique	one Baseline Performance per Property
lodged_sap_score	int	Lodged Performance — gov register, off the Effective EPC
lodged_epc_band	text	the Epc enum, stored as its string value (e.g. "C")
lodged_co2_emissions_t_per_yr	float	tonnes CO₂/yr (whole dwelling)
lodged_primary_energy_intensity_kwh_per_m2_yr	int	PEUI (kWh/m²/yr); not "heat demand" — see CONTEXT.md
effective_sap_score	int	Effective Performance — what modelling scored against
effective_epc_band	text
effective_co2_emissions_t_per_yr	float	tonnes CO₂/yr (whole dwelling)
effective_primary_energy_intensity_kwh_per_m2_yr	int	kWh/m²/yr
rebaseline_reason	text	none | pre_sap10 | physical_state_changed | both
space_heating_kwh	float	EPC renewable_heat_incentive recorded demand. Superseded by heating_kwh (delivered) when the bill block populates; kept until then to avoid an empty-kWh gap, dropped in the population slice.
water_heating_kwh	float	EPC renewable_heat_incentive; superseded by hot_water_kwh.

Bill block (ADR-0014) — the energy bill, composed per section

Produced by Bill Derivation: the calculator's delivered kWh per end use priced at current Fuel Rates (a committed snapshot, not SAP's standardised prices), per section + the total. Per-section kWh is delivered fuel (demand ÷ efficiency — what the household pays for), distinct from the recorded-demand space_heating_kwh/water_heating_kwh above which it supersedes.

Column	Type	Notes
fuel_rates_period	text	which Fuel Rates snapshot priced this bill (e.g. "2026-04 to 2026-06") — provenance
heating_kwh	float	delivered fuel kWh (main + secondary heating)
heating_cost_gbp	float	priced at the heating fuel's current rate
hot_water_kwh	float
hot_water_cost_gbp	float
lighting_kwh	float
lighting_cost_gbp	float
appliances_kwh	float	unregulated load — 0 until the appliances/cooking fields land on SapResult (ADR-0014 TODO)
appliances_cost_gbp	float
cooking_kwh	float	unregulated load — 0 until SapResult carries it
cooking_cost_gbp	float
pumps_fans_kwh	float
pumps_fans_cost_gbp	float
cooling_kwh	float	mostly 0 in UK homes; carried for completeness as it affects the bill
cooling_cost_gbp	float
standing_charges_gbp	float	daily standing charge × 365, once per distinct metered fuel (off-gas fuels have none)
seg_credit_gbp	float	SEG export credit on PV (subtracted)
total_annual_bill_gbp	float	Σ section costs + standing charges − SEG

The calculator is load-bearing (ADR-0013 amendment): for sap_version < 10.2 the effective_* columns hold the calculator's output (so effective_* != lodged_* legitimately); at/above 10.2 they mirror the lodged figures and divergence is logged. A cert the calculator cannot score aborts the batch rather than persisting a wrong row.

Population timing

The bill columns are defined now so the FE can create them, but are populated only once the SapResult → EnergyBreakdown adapter + BillDerivation wiring land (gated on the appliances / cooking SapResult fields). Until then the SQLModel mirror in infrastructure/postgres/ adds these columns as nullable; the Drizzle migration can create them nullable in parallel.