Hi everyone,

I have started looking into Dragonfly and in particular the UWG

I am currently trying to check the sensitivity of the solver with respect to the different parameters using Copenhagen as a reference, mainly because I live there

During one of the tests I tried to set a rural condition for the City definition with 99% of the site covered in grass:

City:

Average Bldg Height: 8 m

Site Coverage Ratio: 0.01

Facade-to-Site Ratio: 0.1

Tree Coverage Ratio: 0.0

Grass Coverage Ratio: 0.99

Building Typologies:

0.1 - LargeOffice,NewConstruction

0.9 - MidRiseApartment,NewConstruction

I have used the following settings for traffic, vegetation and pavement:

Traffic Parameters:

Max Heat: 0.0 W/m2

Weekday Avg Heat: 0.0 W/m2

Saturday Avg Heat: 0.0 W/m2

Sunday Avg Heat: 0.0 W/m2

Vegetation Parameters:

Albedo: 0.35

Vegetation Time: Autocalc - Autocalc

Tree | Grass Latent: 0.7 | 0.5

Pavement Parameters:

Albedo: 0.15

Thickness: 0.5

Conductivity: 1

Vol Heat Capacity: 1600000

Interestingly, the UWG script is still predicting DBT values up to 2°C higher than the original EPW (see attached image for a few days in August):

I would expect the two curves to be very similar, in particular considering that the default assumption for the rural EPW should be a grass coverage of 90%

Am I missing something obvious?

Has anyone experienced a similar trend?

Thanks

Ste