Friday, April 21, 2017

Autodesk Insight 360 - Walls; Part 2

Following yesterday's discussion, Autodesk Insight 360 - Walls; Part 1, on how Revit determines analytical walls from mass elements, I will now shift our attention from mass elements to wall elements.

As seen in the first image below, I created the same "award-wining design" in this post, based on the massing in the previous installment, Notice that this more developed design has parapets, which are defined by a single wall extending from Level 1 up a certain distance above the roof plane.

Revit model created with wall, floor and a roof elements.
When the Energy Analytical Model (EAM) is created in Revit, we see similar results when compared to the previous massing exercise. We have Exterior Walls and Underground Walls.

Exterior Walls element selected in the EAM

Underground Walls element selected in the EAM
If you are paying close attention and comparing the wall area numbers with the previous post you may have noticed the area for the same exterior wall is not quite the same. The reason is that the parapets are automatically omitted from the "exterior walls" equation. The image below shows the EAM has converted the parapet walls to Shade surfaces. This is perfect!

  • It is not as accurate to simply take the literal wall, floor and roof areas and plug them into an equation.

Shading element selected in the EAM
BTW, we can control the visibility of the various parts of the EAM from the Visibility/Graphics Overrides dialog as seen in the image below. This is what I did to create the the images above.

Visibility/Graphics Override dialog for 3D Energy Model view
Once we push this "Revit Elements" based model to Insight we understand this more detailed design iteration results in a more accurate Cost/EUI. It is interesting to see that the super simple thermally zoned mass analysis,from the previous post, offered reasonable close preliminary information.

Walls-based model and Mass-based model in Insight
Setting the Mass Exterior Wall construction to uninsulated also applies to Revit's wall elements. This may be a little confusing since the word "Mass" is in the name of the parameter you are adjusting. When pushed out to Insight, we see the "BIM Setting" is properly positioned at uninsulated for the Wall Construction input.

Insight 'BIM setting' aligns with Revit setting

Like yesterday, I went in and applied an override in the Schematic Types dialog (within the Energy Settings dialog) and selected an R38 construction. When we subsequently push a model to Insight there is something important to understand... the EAM is totally static geometrically and in terms of information. So, if we don't delete and recreate the EAM this new change would not influence the analysis.

When pushing the model to Insight, we are conveniently prompted to automatically recreate the EAM as shown in the image below. However, I think it is best to do it manually and visually inspect it for any irregularities; for example, someone decided to model all the wall types just outside the building.

Insight export prompt within Revit
After deleting and recreating the EAM we get the expected results in Insight!

Insight 'BIM setting' aligns with revised Revit setting
This workflow represents a simple yet powerful opportunity to enhance the performance of most any project being developed in Revit. Like any tool, taking the time to understand it's various parts is key to getting accurate results. Continuing the focus on walls, in future posts, I will talk about using Revit materials to define the thermal properties in a wall, and then another post will look at some things to keep in mind when it comes to Window to Wall Ratio (WWR). So stay tuned for more...

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