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Simulation library

Every model the engine runs: what it answers, what it needs and what it returns.

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How does this compare with ENVI-met, SOLWEIG or PALM-4U? See when to use which tool.

12 modelsWind, perceived heat, sun, daylight and interior.
0.1 to 1 m gridA value every 0.1 to 1 m, from rooms to cities.
One interfacePlatform, plugins and API run the same models.
All simulation models
ModelWhat it showsOutputAligned with
Wind
Wind SpeedAirflow around buildingsm/sVDI 3787-4
Pedestrian Wind ComfortSuitability for outdoor activitiesComfort classLawson (LDDC), NEN 8100, VDI 3787-4
Heat and comfort
Thermal ComfortTime in comfortable conditions% of timeUTCI, Bröde et al. 2012, VDI 3787-2, VDI 3785-1
Heat StressOccurrence of outdoor heat stress% of timeUTCI, Bröde et al. 2012, VDI 3787-2
Cold StressOccurrence of outdoor cold stress% of timeUTCI, Bröde et al. 2012, VDI 3787-2
Microclimate (UTCI)Perceived heat (UTCI)UTCI · °CUTCI, Bröde et al. 2012, VDI 3787-2, VDI 3787-8
Sun and light
Daylight AvailabilityDirect-sun availability0–100% scorePerez all-weather sky, EN 17037
Sky View FactorsOpen sky and enclosure% visible skyVDI 3787-1
Direct Sun HoursDuration of direct sunlightHoursEN 17037 sunlight exposure
Solar RadiationSolar energy reaching surfaceskWh/m²ISO 52010-1, VDI 3789-2, Perez all-weather sky
Interior
Interior Daylight FactorDiffuse daylight inside roomsDaylight factor · %CIE standard sky (ISO 15469), EN 17037
Energy BalanceHeating and cooling energy needkWh/m²·yrISO 13790 monthly method, ISO 52016-1, EN 15265 test cases, ASHRAE 140 (BESTEST), ISO 6946, ISO 13370

How each model was checked: read the validation notes

Wind around buildings

Airflow, gusts and comfort at pedestrian height.

Wind Speed: Hong Kong · wind speed · fixed 0–10 m/s scale

Wind Speed

Where will buildings accelerate wind, and where will they create shelter?

≈ 0.6 m/sBetween buildings≈ 5.2 m/sOpen park area
0 m/s10 m/s
Hong Kong · wind speed · fixed 0–10 m/s scale
Inputs
Building geometry, reference wind speed and wind direction.
Output
Wind speed in m/s across an outdoor ground grid.
Results on
GroundFacades (no)Roofs (no)Rooms (no)
Method
AI model trained on CFD
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Pedestrian Wind Comfort: Hong Kong · annual wind comfort · Lawson 2001

Pedestrian Wind Comfort

Which places support sitting, standing or walking through the year?

Class ABetween buildingsClass DOpen park area
ABCDES15S20
Comfort classes A–E; S15/S20 mark safety thresholds.Hong Kong · annual wind comfort · Lawson 2001
Inputs
Building geometry, a multi-year wind record and a comfort criterion.
Output
Outdoor comfort categories on a ground grid.
Results on
GroundFacades (no)Roofs (no)Rooms (no)
Method
Lawson, NEN 8100, Davenport, VDI 3787
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Perceived heat (UTCI) and comfort

How hot or cold a place feels, and how often it is comfortable. All four models use the UTCI.

Thermal Comfort: Hong Kong · share of daytime hours with UTCI 9–26 °C · annual, 09:00–17:00

Thermal Comfort

Which places remain comfortable during the selected period?

≈ 39%Open park area≈ 57%Between buildings
0%100%
Hong Kong · share of daytime hours with UTCI 9–26 °C · annual, 09:00–17:00
Inputs
Weather, time period, buildings, trees, shade sails and canopies, and facade, roof and ground materials.
Output
Percentage of selected time in thermal comfort at each ground cell.
Results on
GroundFacades (no)Roofs (no)Rooms (no)
Method
UTCI, comfort band 9 to 26 °C
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Heat Stress: Hong Kong · share of daytime hours above UTCI 26 °C · annual, 09:00–17:00

Heat Stress

Where is heat stress recurrent in the selected period?

≈ 38%Between buildings≈ 58%Open park area
0%100%
Hong Kong · share of daytime hours above UTCI 26 °C · annual, 09:00–17:00
Inputs
Weather, time period, buildings, trees, shade sails and canopies, and facade, roof and ground materials.
Output
Percentage of selected time in heat stress at each ground cell.
Results on
GroundFacades (no)Roofs (no)Rooms (no)
Method
UTCI above 26 °C
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Cold Stress: Hong Kong · share of daytime hours below UTCI 9 °C · annual, 09:00–17:00

Cold Stress

Where is winter discomfort recurrent in the selected period?

≈ 2%Open park area≈ 5%Between buildings
0%100%
Hong Kong · share of daytime hours below UTCI 9 °C · annual, 09:00–17:00
Inputs
Weather, time period, buildings, trees, shade sails and canopies, and facade, roof and ground materials.
Output
Percentage of selected time in cold stress at each ground cell.
Results on
GroundFacades (no)Roofs (no)Rooms (no)
Method
UTCI below 9 °C
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Microclimate (UTCI): Hong Kong · perceived heat (UTCI)

Microclimate (UTCI)

How hot or cold does each outdoor place feel?

≈ 31.1 °CBetween buildings≈ 35.6 °COpen park area
28 °C38 °C
Hong Kong · perceived heat (UTCI)
Inputs
Weather, time period, buildings, trees, shade sails and canopies, and facade, roof and ground materials.
Output
UTCI in °C across an outdoor ground grid.
Results on
GroundFacades (no)Roofs (no)Rooms (no)
Method
UTCI (perceived temperature)
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Sun, shade and sky

Sun hours, solar energy, sun access and open sky.

Daylight Availability: Hong Kong · direct-sun availability score · August, 09:00–17:00

Daylight Availability

How reliably does direct sun reach this place during the selected window?

≈ 60%Between buildings≈ 100%Between buildings
0%100%
Hong Kong · direct-sun availability score · August, 09:00–17:00
Inputs
Location, date and hour range, plus buildings, vegetation and terrain.
Output
Direct-sun availability from 0–100%.
Results on
GroundFacadesRoofsRooms (no)
Method
Ray-traced sun positions
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Sky View Factors: Hong Kong · visible sky

Sky View Factors

Where is the site open to the sky and where is it enclosed?

≈ 18%Between buildings≈ 83%Open park area
0%100%
Hong Kong · visible sky
Inputs
Building geometry with optional vegetation, terrain or chosen surface sensors.
Output
Visible sky from 0–100%.
Results on
GroundFacadesRoofsRooms (no)
Method
Hemispherical ray trace
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Direct Sun Hours: Hong Kong · cumulative direct sun

Direct Sun Hours

How long is each place in direct sun?

≈ 88 hBetween buildings≈ 270 hBetween buildings
0 h279 h
Hong Kong · cumulative direct sun
Inputs
Location, date and hour range, plus buildings, vegetation and terrain.
Output
Hours of direct sun.
Results on
GroundFacadesRoofsRooms (no)
Method
Ray-traced sun positions
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Solar Radiation: Hong Kong · façade and roof solar exposure

Solar Radiation

Where does solar energy reach the site and building envelope?

0 kWh/m²136 kWh/m²
Hong Kong · façade and roof solar exposure
Inputs
Weather radiation data, location, time range, buildings, trees and shade structures.
Output
Shortwave solar energy in kWh/m².
Results on
GroundFacadesRoofsRooms (no)
Method
Sun and sky model from weather data
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Room by room

Daylight and energy need inside the building.

Interior Daylight Factor: Hong Kong tower · floor 37 · daylight factor · CIE overcast sky

Interior Daylight Factor

How much diffuse daylight reaches this room under a standard overcast sky?

0%10%+
Hong Kong tower · floor 37 · daylight factor · CIE overcast sky
Inputs
Room barriers, openings, work-plane sensors and optional external context.
Output
Daylight factor as a percentage at interior sensor points.
Results on
Ground (no)Facades (no)Roofs (no)Rooms
Method
CIE standard overcast sky
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Energy Balance: Eight rooms · annual cooling energy need per m² · Hong Kong weather, 2021

Energy Balance

How do envelope, solar gains and weather change heating and cooling demand?

Eight rooms · annual cooling energy need per m² · Hong Kong weather, 2021
Inputs
Spaces, barriers, openings, weather and energy settings.
Output
Monthly heating and cooling need and annual EUI in kWh/m²·yr.
Results on
Ground (no)Facades (no)Roofs (no)Rooms
Method
ISO 13790 monthly method
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