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Script 06 — Storeys

File: sql/scripts/main/06_calc_storeys.sql
Reads from: {city2tabula_schema}.{lod_schema}_building
Writes to: {city2tabula_schema}.{lod_schema}_building (UPDATE)

Purpose

Refines the storey count using the stored room_height value and overwrites area_total_floor with a total heated floor area estimate that accounts for all storeys.

Script 04 computed a preliminary number_of_storeys inline as wall_height / 2.5. This script performs the same calculation but reads from the stored columns, making the room height value explicit and allowing it to be changed per dataset without modifying the SQL.

What it does

UPDATE {city2tabula_schema}.{lod_schema}_building AS bf
SET
    number_of_storeys = bf.min_height / bf.room_height,
    room_height_unit  = 'm',
    area_total_floor  = bf.footprint_area * bf.number_of_storeys,
    area_total_floor_unit = 'sqm'
WHERE bf.building_feature_id IN {building_ids}

Two values are updated:

number_of_storeys

number_of_storeys = min_height / room_height

min_height is the eave height (maximum wall face span from script 04). room_height is the assumed ceiling-to-floor height, defaulting to 2.5 m. Dividing gives the number of storeys in the habitable wall portion of the building.

Guards: if either value is NULL or zero, the existing number_of_storeys is left unchanged.

area_total_floor

area_total_floor = footprint_area × number_of_storeys

This overwrites the value set in script 04 (which was just footprint_area). The result is an estimate of the total heated floor area across all storeys — the metric used in energy demand calculations.

PostgreSQL UPDATE evaluation order

In a SET clause, all right-hand side expressions are evaluated from the row state before the UPDATE begins. This means bf.number_of_storeys in the area_total_floor expression reads the old value, not the newly computed one from the same SET clause. The effect is that area_total_floor is computed as footprint_area × old_number_of_storeys, which is the value from script 04's initial estimate. This is a known limitation and is noted in the script comment. The difference is small in practice because both estimates use the same formula.

What comes next

Script 07 uses the final building feature values — including volume, areas, storeys, and complexity — to match each building to its closest TABULA archetype.