This guide explains every parameter ENVI-met writes into its output files, in plain language: what the value means and why it matters. It is organised by output file type, so you can jump straight to the file you opened in Leonardo or the Spaces/ENVI-guide viewers. The exact set in any given run depends on the model version and which options (thermal comfort, pollutants, greening, water spray, nesting) you enabled.
How ENVI-met output is organised
ENVI-met saves each output time step as a pair of files: an .EDX file (the "header" describing the grid, date/time and variable list) and an .EDT file (the actual numbers). You always need both together — Leonardo reads them as one dataset.
There are several output file types, each focusing on a different part of the model. They are written into separate folders:
Atmosphere — the 3D air volume (wind, temperature, humidity, turbulence…)
Surface — the 2D ground layer (surface temperature, heat fluxes, shading…)
Soil — temperature and water inside the ground below the surface, layer by layer
Radiation — the full shortwave/longwave radiation field and view factors
Vegetation — conditions inside and around plants
Pollutant — concentration and deposition of gases/particles (if enabled)
Building — wall, façade and green-roof/green-wall behaviour (if enabled)
Nesting — the wider model border zone around your core area
Not every parameter appears in every run. Some are only written when you switch on a feature (e.g. thermal comfort PET/UTCI, pollutant species, façade greening, water spray).
A few conventions you will see everywhere
Objects— a marker field that classifies each grid cell (open air, building, vegetation, terrain, source…). It is not a measurement; it helps the viewer draw buildings and plants.Index / grid fields (e.g. Index Surface Grid, Plant Index) — internal ID numbers used to link cells to a building, plant or receptor. Not physical values.
NoData — cells where a value does not apply (e.g. air variables inside a solid building) are filled with a "no data" placeholder and shown as blank.
Key Concepts
Several ideas come up across many parameters. Understanding them once saves re-reading the same explanation in every section.
Potential vs. real air temperature — ENVI-met computes potential temperature (temperature adjusted for height/pressure so air at different heights can be compared fairly). Near the ground the difference is negligible, so for street-level analysis you can read it as ordinary air temperature in °C.
Mean Radiant Temperature (MRT / Tmrt) — the combined temperature of all radiation (sun + sky + hot/cold surfaces) hitting a person from every direction. On a sunny street it can be far higher than air temperature and is the single biggest driver of how hot a person feels outdoors.
Shortwave (SW) vs. longwave (LW) radiation — Shortwave is energy coming from the sun (visible light and near-infrared). Longwave is invisible heat radiation emitted by the sky, the ground, walls and plants because they have a temperature. Both are measured in watts per square metre (W/m²).
Direct, diffuse and reflected shortwave — Direct is the beam straight from the sun's disk; diffuse is sunlight scattered by the sky (what you get in shade or under cloud); reflected is sunlight bounced off the ground and surrounding surfaces.
Upper vs. lower hemisphere — radiation reaching a point is split into what comes from above (sky, building tops, tree canopy) and what comes from below (ground and lower walls).
Sensible vs. latent heat — Sensible heat is energy that changes temperature (you can feel it). Latent heat is energy carried by evaporating water (it cools the surface without raising air temperature — the effect behind plants and wet surfaces cooling a space).
Sky View Factor (SVF) & view factors — the fraction of the sky (0–1) visible from a point. A value of 1 means fully open sky; low values mean a point is boxed in by buildings or trees, which traps heat at night.
Turbulence (TKE) and exchange coefficients — measures of how gusty and well-mixed the air is. Higher values mean the air mixes heat, moisture and pollutants more vigorously.