Net-Zero MultipleX-City
Overview of the Generative Design Tool
The Net-Zero Multiplex-City design tool aids architects and developers build net-zero multiplex building projects, which are more complex and multi-functional than single-tower buildings. The tool allows the developer to
(1) customize the design of each tower (height, radius, rotation, middle width),
(2) optimize the relative position of each tower in the multiplex form to improve its green design, such as green walls, green roofs and solar panels, based on its area and solar insolation, and
(3) evaluate other relevant metrics like total floor area, the volume of the multiplex, and total construction cost.
In addition to visualizing different alternatives and comparing their sustainability/cost metrics, the tool also enables the user to set constraints (i.e. maximum costs) to only generate relevant design alternatives.
User Guide
The user is able to test different forms of the base multiplex design (image above). Input parameters that can be kept as variable or constant are:
- Tower design: height of each tower, base area, rotation of each tower, positions of Towers 2 and 3 relative to Tower 1, middle width
- Building metrics: construction cost (walls and roofs), floor height
For each input parameter, users can choose a value within the range or set it as constant by unchecking the box.
The goal of the tool is to (1) optimize for green design — maximise roof area for green roofs or solar panels, and wall insolation for green walls, and (2) optimize for conventional building metrics — volume and floor area for residential/ commercial/ industrial use and construction cost.
If there are zoning regulations or design needs, the constraints can be entered into the tool to ensure only relevant design options are generated.
Teaser of Possible Results
The user can choose from a range of design alternatives.
The user is able to compare different metrics and their relationships from the parallel coordinates graph and scatterplot graphs. Dragging the axis of the coordinates or clicking on a point in the graph will enable the user to filter out the specific design option.
Finally, the user can visualize the building form on Revit by clicking on the ‘Create Revit Element’ icon.
Limitations and Future Work
First, the ranges of the parameters have been set — the user is able to adjust the sliders on the Dynamo script, but it may be an unfamiliar process. I include an image of the slider below for reference if the user needs some guidance with manually changing the parameters.
The inclusion of more input parameters to allow the user to further customize each tower comes at the expense of greater computational time to run the generative design. Right now, it takes about 2 minutes, which is reasonable, but if the script is updated to include more inputs or outputs (evaluators), it may take a longer time.
The tool has not crashed during its development phase. There may be node/graph issues that appear when the Dynamo script is first loaded, but these issues are resolved once the script is run.
The next step for use on a professional level would be to work with an architect to include more features on the base multiplex design on Revit, such as windows and exterior finishings, to better evaluate the sustainability and cost metrics. For more precise optimization, an overall optimization score can also be calculated by weighing each evaluator to give the top few building alternatives.
Conclusion
This generative design tool is useful in the various insights it can draw out. For instance, increasing the middle width of each tower can increase both surface area and floor area, but at the same time, construction cost — so the user will need to weigh the net benefits of revenue from gross floor area and emissions reductions from green walls vs costs of construction.
Furthermore, based on zoning constraints, the user is able to adjust the maximum and minimum relative positions of Towers 2 and 3 to fit within the relevant grid layout. To fix certain user preferences, the user can also keep some parameters constant to control for the types of design being generated.
Appendix
This assignment builds on Module 7’s generative design tool, but with significantly more features to customize each tower and evaluate additional outputs.
Input Parameters
These parameters of the three towers can be customized by adjusting the following sliders:
- height
- base radius
- middle width
- number of sides
- rotation (degrees)
- x- and y-locations (only for Towers 2 and 3, i.e. offset from Tower 1)
- floor height
The tower geometries were developed by creating a polygon from a circle and extending it vertically by the z-axis based on the height. To provide the layered multiplex design, different ranges of heights were set for each tower. The middle width is scaled from the base radius by a factor of between 0.8 and 1.2.
The multiplex form was created by lofting individual tower solids first, then merging them via Solid.ByUnion.
The project location was set to San Francisco, which can be changed in a new Generative Design study run, but not within each run.
Cost metrics were also included as input parameters for the cost evaluation of the roofs and walls.
Developing the Evaluators: Outputs
To optimize the roof area for solar panels and walls for green features, I created a group of nodes to select them separately for further analysis. The PolySurface.BySolid and PolySurface.Surfaces nodes extracted the surfaces from the tower solid and the surfaces were filtered by calculating their normals (perpendicular if greater than 0, and therefore a roof surface).
The volume, roof area and wall area can be calculated directly from the solid, roof surfaces and wall surfaces respectively.
Next, to calculate the cumulative solar insolation potential on the walls, I used the SolarAnalysis.Analyze node with a grid spacing of 8. This feature is maximized to improve the emissions reduction potential of green walls.
To calculate the construction costs, I multiply the input costs by the wall area and roof area respectively and aggregate them. This will be minimized in the Generative Design study.
Lastly, the floor area is calculated by creating horizontal planes at each floor (based on floor height, an input parameter) and calculating the aggregate plane area that intersects with the solid. This will be maximized in the study as it increases building functionality.
Therefore, the 5 main outputs of Net-Zero Multiplex-City are: total volume, total roof area, total wall insolation, total construction cost, and total floor area.