Methodology

1. Property exposure screening

Around the property the engine samples every 10 m out to 30 m and every 25 m out to 300 m (about 470 points). For each point it reads five Copernicus Land Monitoring Service layers and classes it as forest, shrubland, grassland, farmland, built-up or water.

Distance to the nearest forest or grassland vegetation is measured from the samples and from the Corine polygons out to 900 m. Trees and shrubs inside settlements count towards exposure, and towards the 300 m test only where they cover at least a quarter of the 100 m surroundings; EFFIS burnt areas of mainly natural land count as forest land; an urban grove counts only when the building stands in it. Below 300 m the property is "probably in scope" of the property fire-protection regulation. The binding test is the official forest maps; this result is indicative.

Terrain comes from the Copernicus DEM GLO-30 (30 m), a surface model: the general slope and aspect come from a least-squares plane within 100 m, so single buildings and trees matter less, and landform from the topographic position index over a 150–500 m ring, sea excluded. On built-up or wooded points the slope is marked for confirmation on site. Fire history uses EFFIS burnt areas since 2016. Fire-weather climate is the Canadian Fire Weather Index (FWI) computed from daily ERA5 data. Infrastructure (roads, buildings, power lines, water points) comes from OpenStreetMap.

PYROSIM INDEX (0–100)

100 × (0.30·V + 0.15·D + 0.15·S + 0.05·A + 0.15·H + 0.20·W)

  • V = 0.5·v30 + 0.3·v100 + 0.2·v300: share of vegetation (natural, plus trees and shrubs inside settlements) within 30, 100 and 300 m
  • D = max(0, 1 − d/300): closeness to the nearest forest or grassland vegetation (d in metres)
  • S = min(1, slope/45%): general slope within 100 m (or 250 m, if gentler, where buildings or trees sit on the point)
  • A = (aspect band − 1)/3, with N = 1, NE/E/NW = 2, SE/W = 3, S/SW = 4, flat = 1
  • H = min(1, 0.4·[inside a burnt area] + 0.2·(fires within 2 km) + 0.05·(fires within 5 km)), EFFIS since 2016
  • W = where the area ranks among Greek ERA5 land cells for days per year with FWI ≥ 38 (0 to 1); 0.5 when no cell is available

Levels: below 30 low, 30–49 moderate, 50–69 high, 70 and above very high. The index ranks a location's exposure against other places in Greece; it is not a probability of fire and not the official form category.

For engineers the same measurements are mapped onto criteria groups 5.1 to 5.6 of the official risk assessment form (ΦΕΚ Β' 3475/2023), each with an indicative band from 1 to 4 and its source. Criteria that come from the ΦΕΚ annexes or a site visit are left to the engineer.

2. Fire Weather Index (FWI) System

The Canadian Fire Weather Index (Van Wagner, 1987) is used by EFFIS and worldwide. It is computed daily from noon local temperature, relative humidity and wind and 24-hour rain, through three fuel moisture codes (FFMC, DMC, DC) that start in spring and carry the season's drought forward.

FFMC

Fine fuel moisture

DMC

Duff moisture

DC

Drought code

EFFIS classes: below 5.2 low, 5.2–11.2 moderate, 11.2–21.3 high, 21.3–38 very high, 38–50 extreme, above 50 very extreme.

3. Fire replay: Evros 2023

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4. What PyroSim is not

PyroSim is a prevention and planning tool. It is not an early warning or operational forecasting system, it does not use live data, and it does not determine the legal status of land. In a fire, follow the instructions from 112.

Data sources and licences
PyroSim: Wildfire risk screening for properties in Greece