I created two new parameters for overturning moment and rent premium. The overturning moment assumes a 10lb/sqft of floor area and sums the products of the weight of each floor and its elevation. The rent premium node is an estimation of how much additional rent the owner can get as a premium to the base price per sqft. This accounts for an “exclusivity” factor, which accounts for the fact that we can get more in rent for a smaller floor area (fewer neighbors), and a premium for directness of views to a nearby landmark.
Overturning Moment Node
Rent Premium Node
Overall Evaluator Node (incorporates above custom nodes)
Reported Results
I tried to think of my optimization through the lens of the building’s developer or owner. Life safety comes first and the cost of structural design can be significant to a tower like this, so I gave the overturning moment the highest weight. To take into account the fact that greater overturning moment likely means more cost of structural material and design, I incorporated that item into the optimization using a negative coefficient. Rent premium and gross floor area were equally weighted as they represent the revenue of the building. The normalized values of each of these reported parameters were multiplied by their respective coefficients and summed for each instance.
Here are my assumptions
This method yielded the following results as most optimal (in order):
The best design by this method was the maximum height of those input (720 ft) and the minimal rotation (15 deg). This building definitely maximizes the amount of floor area and premium rent you can get while not trading off too much by creating too much overturning moment.
Do the new evaluation metrics that you’ve designed capture the meaningful differences between the building form alternatives? What other metrics would be useful to compute to help understand and make the case for which alternatives are truly better than others?
Point to Ponder Response
Because each new evaluation metric captures different parts of the design with a directness of view component and a metric based in the distribution of floor area, I think they do capture meaningful differences. That being said, they don’t capture the full picture of what impacts financial risks and investments in the building. Some added evaluators that would be helpful are a calculation of construction cost, construction time, and fire risk.