Energy Simulation, taking into account albedo of urban context

Replies to This Discussion

Permalink Reply by Abraham Yezioro on May 9, 2016 at 8:27am

Marc,

The E+context doesn't take into account the properties of the surroundings. Rather it relates to the context as shading objects, i.e. blocking the sun.

-A.

Permalink Reply by Mostapha Sadeghipour Roudsari on May 9, 2016 at 8:38am

Hi Marc,

RADMaterial will only and only be used when the file is getting exported to Radiance. This is normal that it's not changing the results.

EnergyPlus shading objects don't have a field for reflectance and use .2 as default. You can use ShadingProperty:Reflectance to change the default value. We don't support this in Honeybee interface right now but you can create the objects and add them to your energy model using additionalStrings_ input.

I put a simple example together were I change the reflection for shading surfaces to .5 for unglazed part of shading and portion and .7 for glazed part. I also set the percentage of glazing to 50% of the surface area.

I didn't put any input checks. Make sure to read the documentation to put valid input values for energyplus otherwise the energyplus simulation will fail. I also assumed that all the shading surfaces (context) will be planar surfaces.

Keep in mind that it will only effect the results if you are using one of the solar distributions with reflections. Honeybee is using FullInteriorAndExteriorWithReflections by default so you should be fine if you're using the default settings.

Hope it helps,

Mostapha

Attachments:

• shadingReflectance.gh, 493 KB

Permalink Reply by Abraham Yezioro on May 9, 2016 at 9:38am

Hmmmm,

I learned something new today!!

Always related to the shading objects as they are all under the same conditions.

Thanks,

-A.

Permalink Reply by Theodoros Galanos on May 9, 2016 at 8:58pm

Excellent!

Thanks Mostapha, this can come in handy :)

Permalink Reply by Marc Lotteau on May 11, 2016 at 12:19am

Hi Mostapha,

Thanks a lot for your help!

As I am no expert in e+ your example was really useful!

Marc

Permalink Reply by Mostapha Sadeghipour Roudsari on May 9, 2016 at 9:00pm

Hi Abraham and Theodore, Now that you both seem to be interested do you think that we should add this to Honeybee shading objects as a default option?

Permalink Reply by Abraham Yezioro on May 9, 2016 at 9:25pm

Hi Mostapha,

I do. Do you mean implementing the material properties into the HB_HB_EPContextSrf?

It is important to keep the EPTransSchedule_ input. I'm not sure if there is a chance of conflict between both possibilities ...?

Thanks,

-A.

Permalink Reply by Mostapha Sadeghipour Roudsari on May 9, 2016 at 9:32pm

Interestingly enough EnergyPlus doesn't change reflectance based on transmittance schedule! It stays the same regardless. That's one of the reasons that I was initially so skeptical about implementing it into Honeybee. It can get people pretty confused.

Note that a shadowing transmittance schedule (ref: Shading Surfaces, Field: Transmittance Schedule Name) can be used with a reflective shading surface. However, EnergyPlus assumes that the reflectance properties of the shading surface are constant even if the transmittance varies

Permalink Reply by Abraham Yezioro on May 9, 2016 at 9:40pm

So it is worth to implement, i think.

Thanks,

-A.

Permalink Reply by falko on December 21, 2016 at 3:52am

Hi Mostapha,

is it possible to insert (by an Honeybee tool) the "ShadingProperty:Reflectance" to associate with the "Shading:Building:Detailed" geometry? I would use this parameter in order to set all the reflectance properties of the possible external shadings (louvres, fix shadings etc..). 

If i use the RADmat, does it take into account the Radiance material properties in the E+ calculation? If yes, where is the shading material in the .idf file?

Thanks a lot!

Nic