I chose the Twisting Rounded Triangular Mass with Constant Taper for my building form. I chose to have a floor to floor height of 15ft in my building and divided the mass into floors accordingly. I set my project location as per the brief. I modified the family to have the following parameter values. I chose a Base Radius of 140ft (which was kept constant throughout) to ensure that the plan limits are within the constraints of 300ft x 450ft. To create a tapering effect the mid radius and top radius were made to be 0.75 and 0.5 times the base radius respectively.
For evaluating my alternatives, I built upon my existing Dynamo graph from the previous modules (Flex your Form) submission, where the parameter that was being flexed was the height of the building. The two metrics that I chose to evaluate the performance of my building are - Gross-to-Skin Ratio and Floor Area Ratio.
(Source: testfit.io/building-metrics/)
The Gross-to-Skin Ratio gives us an idea of the compactness of the building. It is essentially the ratio of the cumulative floor areas to the cumulative floor perimeters.
(Source: testfit.io/building-metrics/)
Floor Area Ratio gives us an idea of the total building area compared to the site it sits on. If a building has a low FAR compared to the building next to it, then there might be an opportunity to increase its intensity. Sites governed by FAR are incentivized to create buildings that are as efficient as possible.
Following are the steps that I used to create my Dynamo graph:
I modified the BuildingForm.EvaluateSingleInput custom node provided to compute the values of the metrics that I introduced for building evaluation. Shown below is the dynamo logic for this function (BuildingForm.EvaluateSingleInput):
The next step was to test each of the different heights and choose the results to report.
Next, I used the existing custom node BuildingForm.EstimateCostByFloorLevel along with a slightly modified version of the existing custom node used for massing floors (LasyaMassingFloors); to evaluate the value of the building floor areas.
Shown below is the dynamo logic for LasyaMassingFloors:
The first custom node that I created was the Computing Skin-to-Gross Ratio. I massed the floor areas and utilized the Floor Perimeter parameter along with the Floor Area parameter to compute the Skin-to-Gross ratio.
Shown below is the dynamo logic for the custom node (BuildingFormComputeskintogross):
The second custom node I created was to determine the Floor Area Ratio. Also shown below is the dynamo logic for this custom node (BuildingFormComputeFAR):
The last step was to export the results to Excel
Shown below is the Excel sheet with the computed values of Gross Floor Area, Gross Surface Area, Gross Volume, Cost, Skin-to-Gross Ratios and Floor Area Ratios for the different heights:
The values with the green dots next to Gross Floor Area fall in the desirable range of new floor area. Keeping in mind the objectives of minimizing cost, minimizing surface area, maintaining a reasonable level of compactness (Gross-to-Skin ratio) and a reasonable level of Floor Area Ratio, I would recommend that the tower form with a height of 650ft be proposed.
