Your ENVI-met model area is only a small cut-out of a city. The air flowing into it, and the buildings and trees just beyond its edges, still shape the microclimate inside it. With the Surrounding Area setting in Spaces you describe what lies beyond each border of your model by choosing one of 27 ready-made urban or land-cover presets, without digitizing the surroundings cell by cell.
Surrounding Area is new in ENVI-met 6.0 and replaces the nesting grids of earlier versions.
What the surrounding area does
It characterises the urban context upstream of your model, which shapes the wind profile flowing into the model area.
It adds the radiative effect of the surroundings: shading and longwave radiation from the "virtual skyline" beyond each border.
Set the surrounding area in Spaces
In Spaces, select your project and open your model area.
Click Start ▸ Edit Area / Create New Area (or press Ctrl+N). The window Change or create model domain settings opens.
Open the Surrounding Area tab.
Make sure Add generic surrounding area around model domain is ticked.
Choose a preset for the Top border, Right border, Bottom border and Left border.
Click Apply changes to existing area, then save your model area.
Use Apply changes to existing area to keep your model. Create new empty area starts a new, empty model area and discards your current model.
Which border is which
The border names refer to the 2D map in Spaces:
Top border: the upper edge of the map (grid north)
Right border: the right edge (grid east)
Bottom border: the lower edge (grid south)
Left border: the left edge (grid west)
If your model is rotated (Model Geometry tab ▸ Model rotation out of grid north), the borders do not face true north, east, south and west. Turn on Show / hide north arrow in the 2D toolbar to see where true north lies before you assign the presets.
Choosing a preset
Look at the area beyond each border at neighbourhood scale and pick the type that dominates it. Local Climate Zones typically describe areas of several hundred metres up to a few kilometres.
Pay particular attention to the border(s) the wind blows in from during your simulation, because the upstream surroundings shape the incoming wind.
Using aerial imagery or LCZ maps can help you classify the surroundings.
The presets, in the order they appear in Spaces:
Preset | Group | Corresponding LCZ |
Compact high-rise | Urban | |
Compact mid-rise (default) | Urban | |
Compact low-rise | Urban | |
Open high-rise | Urban | LCZ 4 |
Open mid-rise | Urban | |
Open low-rise | Urban | |
Lightweight low-rise | Urban | LCZ 7 |
Large low-rise | Urban | |
Sparsely built | Urban | LCZ 9 |
Heavy industry | Urban | |
European perimeter block | Regional urban type | – |
Open row housing | Regional urban type | – |
Historic dense core / old town | Regional urban type | – |
Dense high-rise residential (tower blocks) | Regional urban type | – |
Dense low-rise vernacular (shophouse / hutong) | Regional urban type | – |
Downtown high-rise core (CBD) | Regional urban type | – |
Detached suburban housing | Regional urban type | – |
Urban park / green space | Regional urban type | – |
Dense trees / forest | Natural / land cover | LCZ A |
Scattered trees | Natural / land cover | LCZ B |
Bush, scrub | Natural / land cover | LCZ C |
Low plants / grassland | Natural / land cover | LCZ D |
Cropland / agriculture | Natural / land cover | – |
Wetland / marsh | Natural / land cover | – |
Bare soil or sand | Natural / land cover | LCZ F |
Bare rock or paved | Natural / land cover | LCZ E |
Open water | Natural / land cover | LCZ G |
Read more about the classes in Local Climate Zones (LCZ) in summary.
Models from earlier ENVI-met versions
When you open a model area created with an earlier ENVI-met version, Surrounding Area is switched on automatically with Compact mid-rise on all four borders. Open the Surrounding Area tab and adjust the presets to the real surroundings.
Surrounding Area replaces the nesting grids. Nesting-grid settings from older models can no longer be edited.
Keep a copy of your older model area files before saving them in ENVI-met 6.0. Saving replaces the file with the new 6.0 format.
Switching the surrounding area off
Untick Add generic surrounding area around model domain. The four border lists are then greyed out, and no surrounding area is used for this model.