AutoEnvelope

As the name suggests, this tool uses the principal of generative design to help designers and engineers produce well informed decisions on the building envelope and the optimal exterior wall sections for a given project during the concept design phase.

The Inputs that can be varied are as below:

i. Material Selection:

Aluminum Cladding or Brick
Plywood or DensGlass
Metal or Wood Studs

ii. Thicknesses of Each Layer below:

Cladding/Masonry
Outer Insulation
Plywood/DensGlass Sheathing
Stud Size (with batt infill)
Drywall

A video demonstration is as shown:

Implementation

The node logic is as shown below:

For material selections, the sliders act as a toggle button where 0 is the first selection and 1 is the second selection. The remaining integer sliders vary the thickness (in inches) of a given layer:

These inputs as well as the selected model element (a wall with 5 layers) feed into a series of nodes that overwrite the material properties of the selected layer in the wall as shown:

Similarly, the same inputs feed into a series of nodes that overwrites the thickness of each layer. The units are also converted between feet and inches as required.

Once the materials and thicknesses of each layer is set, the R-value of the final wall section is calculated as shown. The final R-value is set as an Output.

Similarly, the cost per SF ($) of wall section is calculated and set as an output:

Similarly, the Carbon Emissions per SF (lb CO2e) of wall section is calculated and set as an output:

Finally, the total thickness of the layer is set as an output by summing up the thicknesses of each layer:

Now, a generative study is run with the following settings:

The following generative design results are generated. As an example, we will filter out any wall thicknesses over 15” as it may be too thick:

Shown below is a chart of R-value versus thickness of wall.

The larger the scatterplot’s data point, the higher the cost.

The color scale for the Carbon Emissions is as shown:

The tradeoff is very clear - as the R-value increases, either the thickness of the wall must increase or the cost and carbon emissions must increase. (In some cases, 2/3 or all 3 increase.)

The sweet spot are the red values, which are environmentally friendly and cost effective, but unfortunately, their R-value does not go higher than R-23 within the space constraints. For example: