Dear Envi-met-Team,

at the moment I'm trying to analyze the results for a building with a facade greening with an Air gap. But the naming of one of the Variables is not clear to me.

Do I understand it correctly that "Building: Sum Humidity Flux at facade (g/sm3)" is located in front of the greening(not in front of the wall)?

I need the sum of water that is released of evaporing from substrate and the greening (transpiration/evaporation). Is the "Building: Sum Humidity Flux at facade (g/sm3)" the right variable for this? Where does the humidity go when the value is negativ?

Thanks a lot in advance.

## Output Variables

### Re: Output Variables

Hi,

Yes, it is located in front of the greening and includes the total humidity flux of the system (wall, air gap, substrate, greening). If it is negative, humidity of the surrounding goes into the system. Positive means the system emits humidity into the surrounding.

Best regards,

Tim

Yes, it is located in front of the greening and includes the total humidity flux of the system (wall, air gap, substrate, greening). If it is negative, humidity of the surrounding goes into the system. Positive means the system emits humidity into the surrounding.

Best regards,

Tim

### Re: Output Variables

Hello Tim,

thanks, that helped me a lot.

One more question to this topic: Does Envi-met includes water vapour diffusion through the wall?

From the view of a building physicist the water vapour diffusion through the wall might be negligible because of the air gap, which is normally ventilated. But I read in another post (link below) that Envi-met does not include a ventilation of the air gap, so the included characteristics of the water vapour diffusion would be important for me.

Maybe there is also a document about the calculations for "Building: Sum Humidity Flux at facade (g/sm3)" that I havn't found yet?

Thanks in advance.

viewtopic.php?f=31&t=3232&p=10268&hilit=air+gap+ventilation&sid=4723212be6d84a1fa416b8c241f05952#p10268

thanks, that helped me a lot.

One more question to this topic: Does Envi-met includes water vapour diffusion through the wall?

From the view of a building physicist the water vapour diffusion through the wall might be negligible because of the air gap, which is normally ventilated. But I read in another post (link below) that Envi-met does not include a ventilation of the air gap, so the included characteristics of the water vapour diffusion would be important for me.

Maybe there is also a document about the calculations for "Building: Sum Humidity Flux at facade (g/sm3)" that I havn't found yet?

Thanks in advance.

viewtopic.php?f=31&t=3232&p=10268&hilit=air+gap+ventilation&sid=4723212be6d84a1fa416b8c241f05952#p10268

### Re: Output Variables

Hi,

No, water vapour diffusion through the wall is not calculated.

I don't know of any document about the Building: Sum Humidity Flux at facade (g/sm3), yet.

Best regards,

Tim

No, water vapour diffusion through the wall is not calculated.

I don't know of any document about the Building: Sum Humidity Flux at facade (g/sm3), yet.

Best regards,

Tim

### Re: Output Variables

Dear Tim,

I tried to find some information to get an impression how the "Building: Sum Humidity Flux at facade (g/sm3)" is calculated. I'm just not able to find anything that could help me.

For my reseach it is nessesary to understand what is happening with the humidity in the greening-system. I need the data as input values for another simulation (a hydrothermic simulation). I need to know what exactly the "Building: Sum Humidity Flux at facade (g/sm3)" represents to display the situation correctly. Is there any equation you could give to me or could you please explain to me more detailed where the humidity comes from (e.g. air humidity, transpiration, evaporation of soil?) and goes to (soil, air gap?)?

For this I would be very grateful!

Best regards,

Greenie

I tried to find some information to get an impression how the "Building: Sum Humidity Flux at facade (g/sm3)" is calculated. I'm just not able to find anything that could help me.

For my reseach it is nessesary to understand what is happening with the humidity in the greening-system. I need the data as input values for another simulation (a hydrothermic simulation). I need to know what exactly the "Building: Sum Humidity Flux at facade (g/sm3)" represents to display the situation correctly. Is there any equation you could give to me or could you please explain to me more detailed where the humidity comes from (e.g. air humidity, transpiration, evaporation of soil?) and goes to (soil, air gap?)?

For this I would be very grateful!

Best regards,

Greenie

### Re: Output Variables

Hi,

I know that there is no information on equations and technical background yet but be sure that is in development and will be released within the next months.

For the general understanding I can only quote what I said above:

Splitting up is not possible here since it is the sum of all humidity fluxes such as transpiration/evaporation of soils and greening or uptaking of water from greening. It says if the whole greening wall soil system rather takes in humidity or rather releases humidity to the surrounding air.

Here the equations about it:

humidityFluxWall [g/kg*s] = Greening.LADweighted [m2/m3] * (greeningPlant.evaporationFlux [g/kg*m/s] + greeningPlant.transpirationFlux [g/kg*m/s])

humidityFluxWall [g/kg*s] = humidityFluxWall [g/(s * m³)] + SurfaceFactor [Ratio wall surface per grid volume] * greeningSubstrate.j_evaporationFlux [g/kg*m/s]

humidityFluxWall [g/(s * m³)] = humidityFluxWall [g/kg*s] * 1,29 (Density of air [kg/m3] at 20°)

Best regards,

Tim

I know that there is no information on equations and technical background yet but be sure that is in development and will be released within the next months.

For the general understanding I can only quote what I said above:

If it is negative, humidity of the surrounding goes into the system. Positive means the system emits humidity into the surrounding.

Splitting up is not possible here since it is the sum of all humidity fluxes such as transpiration/evaporation of soils and greening or uptaking of water from greening. It says if the whole greening wall soil system rather takes in humidity or rather releases humidity to the surrounding air.

Here the equations about it:

humidityFluxWall [g/kg*s] = Greening.LADweighted [m2/m3] * (greeningPlant.evaporationFlux [g/kg*m/s] + greeningPlant.transpirationFlux [g/kg*m/s])

humidityFluxWall [g/kg*s] = humidityFluxWall [g/(s * m³)] + SurfaceFactor [Ratio wall surface per grid volume] * greeningSubstrate.j_evaporationFlux [g/kg*m/s]

humidityFluxWall [g/(s * m³)] = humidityFluxWall [g/kg*s] * 1,29 (Density of air [kg/m3] at 20°)

Best regards,

Tim

### Re: Output Variables

Hi Tim,

Thanks for the equations. This will probably take me to where I need to go.

But unfortunately I don't seem to fully understand the formulas. The result is always the humidity flux at the wall (in front of the greening?)? But the units of the first two calculation don't lead to the units of the results? In the last equation there is the humidity flux at the wall on the one hand in the calculation and on the other hand in the result but with different units.

I'm realy sorry, but it's confusing me.

Best regards,

Greenie

Thanks for the equations. This will probably take me to where I need to go.

But unfortunately I don't seem to fully understand the formulas. The result is always the humidity flux at the wall (in front of the greening?)? But the units of the first two calculation don't lead to the units of the results? In the last equation there is the humidity flux at the wall on the one hand in the calculation and on the other hand in the result but with different units.

I'm realy sorry, but it's confusing me.

Best regards,

Greenie

### Re: Output Variables

Hi Greenie,

Sorry, I had a copy paste error there with the units for the humidityflux. It is corrected now in the post above. The first two are happening during the main routines. The last line only happens before writing the output.

Best regards,

Tim

Sorry, I had a copy paste error there with the units for the humidityflux. It is corrected now in the post above. The first two are happening during the main routines. The last line only happens before writing the output.

Best regards,

Tim

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