I have some problems, thank you for your help me.
- I want to obtain the effect of evaporation and perspiration of green walls and vegetation and water to calculate outdoor thermal comfort UTCI.
Is there a solution to this problem in honeybee and ladybug?
Can this effect be considered with Dragonfly?
- I want to produce various green materials in Haneybee, such as Low vegetation and grass. How do I do that?
In the model “providedhttp://hydrashare.github.io/hydra/viewer?owner=chriswmackey&fork=hydra_2&id=Green_Roof_In_Energy_Model&slide=0&scale=1&offset=0,0”
by dear @chris , I do not know where the information in this panel came from?
Here you can find more information on what is exactly calculated.
@Erikbeeren , thank you for your help🙂
FYI the Dragonfly-UWG component, (used to model UHI) models the impact of vegetative transpiration from green roofs, trees and grass (although in a crude way).
The UWG subtracts a fraction of sensible heat gain from the net radiation absorbed by vegetation to represent the latent impact of vegetation. These are represented by the grass and tree latent fraction inputs in the GH component.
The model thus assumes that plant stomata is closed after sunset, so transpiration is a function of net radiation, and furthermore the latent heat to net radiation flux is constant (there are studies that back this up). However, the impact of different tree/grass ratios are not incorporated into the UWG air moisture balance, so the transpiration impact is limited to just the surface heat balance of vegetated roofs, and the grass/tree cover on the ground.
@farnoosh @SaeranVasanthakumar ,
I once created a outdoor surface temperature animation using honeybee_legacy. For the input epw I used the UrbanWeatherGenerator from dragonfly. For the grass spots I used the definition above. For the pavement I used concrete as material. For the soil/pavement I used “create EP ground”
The result was this animation:
The effect of the of the different materials was clearly visible.
First of all, thank you for @SaeranVasanthakumar’s good explanation.
@Erikbeeren , I wanted to ask exactly the same question.
Is it possible to attribute the material to the zones through the Honeybee, then add vegetation and trees through the Dragonfly, and finally include “environment temperature” in the UTCi index through the ladybug?
Is it possible?
Yes you can add this material to Honeybee constructions.
For this simulation I made a new EPW file using UWG from Dragonfly.
This EPW I used for the input in Honeybee. The whole simulation I did in honeybee.
The pavement I modeled as “EPground” zones.
Buildings I modeled as zones.
Trees I modeled as context (it takes only into account the shading caused by these trees which is probably a bit to optimistic).
For the UTCi workflow I am afraid I can’t help you.
Thank you very much for your good guidance.
I do this and review the results.
I would add that the UWG component in Dragonfly is a good candidate for modeling your microclimate only if it is developed with many buildings. It’s only meant to be used where the rural context of the EPW from airport weather stations won’t capture the urban heat island effect in more developed areas.
For scenario’s where you want to model in high resolution the impact of vegetation on outdoor microclimate, I believe ENVI-met is considered state of the art, although I personally have never worked with it.
Hi @Erikbeeren , @chris ,
Is there a way to define a green roof in the new Ladybugtools 1.2, like in the Honeybee legacy version? Or a workaround?
It looks like 1.2 does not like vegetation roofs.
Yes, I still have to implement the vegetation material in the LBT plugin and there’s an open issue for it:
I’ll try to implement it when I get the chance, though, if anyone else wanted to tackle the initial implementation in honeybee-energy there, I would gladly review the PR and merge it.
Hi @chris, thank you for all your support. did you solve the issue? I am trying to model a green roof and want to see what is the impact on the building surface. but it mapped even warmer.
It’s still not implemented yet. I think @TrevorFedyna had started to work on it a few weeks ago but I don’t know how far he has gotten. There are some ways of hacking it with the OpenStudio SDK if you’re willing to use a workflow like that described here and you need it now.
I’d gotten a decent bit written out, and was working on tests and debugging before having to save and work on some time sensitive projects but starting later this week I’ve a good bit of time blocked out for this and a number of other additions & projects!
should have PR today or tomorrow: just have to write the tests and debug as applicable