Firstly, I want to thank this great team, especially Chris.
I have a question: When providing an EPW file for generating a UHI plot, does DF consider energy and HVAC consumption, as well as the heat generated by buildings? I understand we import our models, but are there any PDFs detailing the assumptions of this tool?
Additionally, if I want hourly CO2 data for Canadian cities, what should I do? Is there a way I can assist your team in generating this data?
When I change the construction set, there is no noticeable effect on the Urban Heat Island (UHI) temperature difference. I adjusted the solar absorptance to observe the effect of reflectivity on the urban area, but I didn’t notice any change. In Honeybee Energy, modifying the surface absorptivity allows you to see changes in surface temperature and its impact on building energy consumption. However, in Dragonfly, no such changes are evident.
Thanks for the kind words. To make sure that I understand what you are asking about, are you talking only about the morphing of EPW files to account for urban heat island using the Urban Weather Generator (UWG)? So you are basically just using the workflow in this Grasshopper sample file and you are not really asking about building energy modeling (BEM) but you are instead interested in urban heat island modeling?
If so, you’ll find a lot of your answers on the UWG GitHub repository that I linked to above. The UWG runs a full energy balance of the buildings that surround an idealized urban canyon with characteristics generally matching the dragonfly buildings. But the constructions of these buildings are not likely to have much of an impact on the heat island effect in the urban canyon unless you are changing the insulation by a large amount and you have also set the buildings up such that the heat they reject goes into the urban canyon (rather than above the buildings). You can change this rejection factor with the DF Assign Building UWG Properties component.
Thanks again. I am currently researching the effect of the albedo of walls and roofs on the mitigation of the Urban Heat Island (UHI) effect. I am using Dragonfly for my simulations, and I find it very useful. However, I encountered an issue: when I increase the surface reflectivity within the construction set, there is no difference in the UHI calculation. There should be a temperature difference in the new EPW file since the heat absorption from the sun decreases with more reflective surfaces. I plan to use the UWG parameters that
That’s because the construction set does not changing the parameters for UWG simulation of the urban canyon. If you want to change the wall albedo in this calculation, you must use the DF Assign Building UWG Properties component to change the wall_alb_ assigned to your buildings in UWG simulation.