# Create shade vs shade benefit analysis

I want to study the energy saving of shade design.

First, I use EPwindowShadeGenerator and calculate the EUI and sDA;

Second, I use shade benefit analysis to get saved energy.

Third ,I compare the first and second results.

for example：exter blind, shdAngele is 17, the EUI is 75kWh/m2(witout shade the EUI is 78kWh/m2 ), but shade saved energy is 2095. In my opinion, according to the shade saved energy(2095), the EUI saved by shading should be higher.According to the envisage, the light environment should be changed with the shade design,but the sDA is same.I think this simulation is wrong，but I don’t know where the problem is. If my question is not clear, please let me know.Please help me.
Thanks.

I’m sorry, this is the relevant document。office room.3dm (42.2 KB)
wwr-create shade-E .gh (657.1 KB)

Hi @TianYixin,
I checked your model and I get the following results;

kwh/m2 without blinds = 230
kwh/m2 with blinds = 202

sDA without blinds = 95.83
sDA with blinds = 61.46

Whenever running a daylight simulation, it is always advised to perform an image based simulation to see that the geometry is imported in radiance as it should. In you case, the blinds were not imported as radiance geometry therefore there was no change in sDA. I fixed that in the attached file.

wwr-create shade-E .gh (681.3 KB)

Hi @devang
Your method is right. I have solved the problem of sDA now.
But I still don’t know the energy saving problem of shade. According to the energy shade benefit evaluator, the amount of energy saved is 2095;According to Energyplus simulation, the energy saved is only 3kWh/m2(without blinds=78kWh/m2,with blinds=75kWh/m2 ).I think this value（ saved energy 3kWh/m2） is too small, there is a problem.

Thanks for your help

Hi can you please share which weather file you are using and also if any specific analysis period you are using. I seek this ao that, we start looking at the same numbers.

Hi @devang
CHN_Shaanxi.Xian.570360_CSWD.epw (1.7 MB)
Thanks.

HI, I have the same issue, Energy simulation doesn’t show the impact of shading devices from the Context component. It looks like the resolution or number of maximunFigure can’t capture small objects such a fins. I went from 3000 to ten millions of points. It only accounts for Buildings and big trees.

On the other hand, EP Window Shades component is supposed to attach the shading to the zone. However the HBOjWShades outputs has nothing on it. Even though it creates the shades it says:

NHBObjWShades will not be generated. shadeBreps will still be produced and you can account for these shades using a ‘Honeybee_EP Context Surfaces’ component.

What is the right way to represent shading devices for energy analysis?

thank you guys

You maybe try like this.