Effect of greenings

This is the place to post and discuss your project results, ideas, visions and other things in your mind (...-related to ENVI-met ;)...) with other users.

Remember: This is a forum on technical Q on ENVI-met. We can not/ will not analyse your project results for you(although we might give hints).
Erika
Posts: 11
Joined: Mon Mar 09, 2020 9:19 am

Effect of greenings

Postby Erika » Fri Mar 20, 2020 2:59 am

Hello everyone,

I'm struggling with the interpretation of a simulation result.
I am trying to show the effect of greenings on air temperature by comparing the air temperature values right next to a concrete building facade, with and without greenings. Due to the theoretical notions I have, I expected to find lower temperatures in the case with greenings. However it happens the air temperature is the same in both cases, for all the points.
I used a wall made up of (from outside to Inside) 25 cm of default cast dense concrete, 10cm of default insulation and 5cm of default plaster. Then I added the default green + sandy loam substrate (without air gap) on the outside.

I think the amount of sandy loam substrate (which absorbs heat), the thickness of the wall or the insulation could affect the results, so I am doing more tests, but actually I don't fully understand the mecanism that steps in. Nevertheless, the specific humidity is higher with greenings and this is what I was expecting.
So I would like to know if you think I could have done Something wrong.
Thank you in advance for your help.

Best regards,
Erika

Tim
Posts: 1393
Joined: Mon May 15, 2017 3:46 pm

Re: Effect of greenings

Postby Tim » Fri Mar 20, 2020 7:57 am

Hi Erika,

Effect of greening on air temperature might not be as big as you expect it. However, it should be slightly cooler.
You may calculate biometeorological indices with BIOMET to get an idea about the improvement of thermal comfort.

Best regards,
Tim

Erika
Posts: 11
Joined: Mon Mar 09, 2020 9:19 am

Re: Effect of greenings

Postby Erika » Thu May 07, 2020 3:33 am

Hi Tim,

I followed your advice and calculated the biometeorological indices UTCI and PET. However the results lead to the same conclusion, that is to say that the green facade leads to slighty higher temperatures regarding comfort. I know this isn't right so i'm trying to understand why I have those results. I tried to change the type of greening (with/without air gap, substrate etc) but the result is always the same.
However I noticed that the relative humidity is higher with greening so it has to have an effect.

Finally I Wonder if the problem could come from the fact that I just have one building in my area so there is no interaction with other objects. What do you think ?
I also Wonder if there is a greening parameter I could change in order to "force" the effect and then see where is the problem in my simulation.

PS: I don't expect you to interpret my results. I just want to make sure I didn't make a wrong manipulation.

Thank you for your help.

Best regards,

Erika

Tim
Posts: 1393
Joined: Mon May 15, 2017 3:46 pm

Re: Effect of greenings

Postby Tim » Thu May 07, 2020 6:44 am

Hi Erika,

I could imagine that having only one building without any shadowing for the facade might be a problem for the plants. If leaves get too hot they close their stomatas and the cooling effect does not take place.
You could also check the water coefficient. If it gets closer to 1, the plants have more water available from the substrate.

Best regards,
Tim

Erika
Posts: 11
Joined: Mon Mar 09, 2020 9:19 am

Re: Effect of greenings

Postby Erika » Fri May 15, 2020 2:50 am

Hi Tim,

I have simulated several buildings and the result is still the same. I checked the water coefficient, it is equal to 1.

I noticed that the value of the "greening:transpiration flux" reaches a maximum of 0.11 g/s*m3 but I don't know wether it is a normal value or not, as I didn't find any documentation on the subject. Do you know something about it ?
Besides, How can I check wether the greening is working correctly or if it is too hot ?
I still have a lot of questions about facade greening. Having the business licence, is there a specific email I could write to or a number I could call for technical issues ?

Thank you for your help.

Best regards,

Erika

Tim
Posts: 1393
Joined: Mon May 15, 2017 3:46 pm

Re: Effect of greenings

Postby Tim » Fri May 15, 2020 10:01 am

Hi Erika,

What do you mean with the result is the same? Maybe, the differences are much smaller than expected but there should definitely be differences. You could help us with helping you if you attached your test files as zip (SIMX, INX, EDB etc.).
You may check leaf temperatures to see if they get too hot. They are limited to 45 °C at the moment which may also affect the transpiration flux (limiting it to the value that you observed for your greening and your met. conditions).
Unfortunately, the technical documentation about greening is still in development. However, all experts with access in the code are available through this platform here and can give you the information which is needed.

Best regards,
Tim


Return to “Projects & Results & Ideas”

Who is online

Users browsing this forum: No registered users and 1 guest