Diva-Grasshopper kWh Ouput is very high

Hi everyone,

I modelled an average american home and set the parameters to Chicago Ill, where I have census data already. I wanted to compare the output from Diva in total electricity required to the census data. The output values from Diva were over 10X the census data. Diva is outputting a extremely high estimate of the kWh requirementfor this building. Any suggestions about why this may be happening would be much appreciated. Thank you!!

Replies to This Discussion

Permalink Reply by Jeff Niemasz on October 29, 2012 at 6:47am

Hi Miles,

Right now you can only run a single zone in Viper, so it is best used for facade studies on initial loads on the system and not for a full building energy simulations. You would need probably a minimum of 4-5 zones to model a house adequately (to take into account the differences in gains on the different facades (N,S,E...). You would also have to match the insulation and HVAC systems to the typical census house you are comparing. Can you post the rhino model and the simulation parameters for the model house and the typical census house your are comparing ? (Insulation types, square feet, window to wall ratio, window area on south side, etc...)

Jeff

Permalink Reply by Miles Miller on October 30, 2012 at 4:15pm

Hi Jeff, thank you for your reply. I am going to post the screen shots of the rhino setup I am using. Diva is setup with a single plane for both the roof and floor. The walls planes are made of metal, and the window planes are on top of the wall planes. I have the house oriented correctly in the model. The facades are nearly identical and there are no interior walls in the space except the bathroom utility area. It is only 1500 square feet on the inside.

I am also posting a screen shot of the typical residential model. It is 1865 sq ft with no walls modelled on the interior. Thank you again... Your help is much appreciated!!!!

-Miles

Attachments:

typical residential screen shot.jpg, 999 KB
grasshopper screen shot.jpg, 672 KB
rhino screen shot.jpg, 931 KB

Permalink Reply by Jon Sargent on November 2, 2012 at 6:00pm

Hi Miles,

I would second Jeff's comment about the use of Viper. The open-plan house you've described would still benefit from multi zone analysis, as there are uneven gains on the different facades, etc. With that said, a couple comments:

1) It's a bit strange to have an uninsulated metal facade, no?

2) The little green pop-outs attached to each component is a signal that your DIVA-for-Grasshopper is out of date! You can install the latest version of DIVA here.

-Jon

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