Twisting Rectangular Mass Form
For my module 6 I built off my existing dynamo script from module 5 which flexed the form of my Twisting Rectangular Mass. My dynamo main script however know also adds two additional testing parameters which include the total kg CO2e produced over the lifetime of the structure as well as the roof deflection of the tower under a uniform wind load. These parameters for various building heights and twist angles were reported as well as the Gross Floor Area, Gross Surface Area, and Gross Volume.
Main Dynamo Script
The above picture is zoomed out version of my main dynamo script which runs the analysis. This analysis flexes the parameters of the height and the twisting angle and is almost identical to the main script which I have in module 5. The main differences include new input parameters which are required for new custom evaluation metrics of kg CO2e and wind displacement. I also have a modified testing node which is called BuildingFormEvaluateMultipleParamsModule6. This custom node includes the two new custom nodes I created and the inputs associated with them. This custom node then add the evaluation metrics computed to the output list which is displayed in excel. Below is an image which can better show the custom node: BuildingFormEvaluateMultipleParamsModule6.
New Input Parameters in Main Script
Above are the input parameters which are needed for both of my custom nodes. For my custom node to compute total kg CO2e over the lifetime of the building, the parameters needed include: building lifespan, energy consumption per year per sf, California grid kg CO2e/kwh released, and embodied carbon per sf. For my custom node of computing the roof displacement due to wind load, the parameters needed include average uniform wind load per SF of surface area, average weight of building per SF, and the height of the building.
Above is a picture of the evaluation node which includes my two custom nodes and the relevant inputs. Note when inputting the custom nodes it is important to grab the building form from after the transaction end point. You also need to create the relevant inputs for the custom nodes and then plug the outputs into the lists nodes which collect the results to be reported.
CO2e Custom Node
One of the custom nodes I created computes the total kg CO2e released per the lifetime of the building. It sums the embodied carbon of the building as well as the operational carbon released during the buildings life span. The embodied carbon is calculated using an estimate from a Denver.gov building report that commercial high rise buildings release 42 kg CO2e/SF for the embodied carbon. I then used this estimate and the total floor area to get a rough estimate of the embodied carbon.
For the operational carbon I used an average building lifespan of 60 years. I also used the metric of 22.5 kWh/year/sf of energy used for a building. Looking at the California’s grid output of .88 kgCO2e/kwh, I then multiplied the lifespan of approximately 60 years by the energy used per sf per year times the kgCO2e released per kwh times the total floor area of the building.
With both the operational and embodied carbon computed, I summed them together to get an approximate total kg CO2e released during the lifetime of my building. Below is the logic for the custom node.
Wind Displacement Custom Node
The other custom node I created used some knowledge of structural engineering as I am a structural engineer. This custom node computes a very rough estimate of the roof displacement under an assume uniform distribution of wind load of 50 psf. I researched and found this to be a 100 year return period storm. In order to calculate this displacement there are a number of assumptions which I used to simplify the calculation. I first assumed a SDOF system with all the mass at the top of the structure, I also assume the period of the structure as .1*N where N is the number of stories. I also assumed a uniform distribution of wind load across one face of the building.
Computation: Under all these assumptions, I first found the max area of a face of the building. I found this face by extracting the surfaces of the rectangular mass form and then taking those surfaces and using a surface to area node. I then found the max surface and computed the wind force on that max face. To compute the stiffness of the structure I computed the mass of the building and the approximate period of the structure and then used those two values to compute the stiffness given that wn^2=k/m and wn=2*pi/Tn.
With the force and stiffness calculated you can simply divide the force by the stiffness to get the displacement. Below is the logic for the custom node.
Evaluation Metrics to Report
Above is the exported excel file which includes all the evaluation metrics to report as well as the inputs that are flexed of building height and the twist angle. I would choose the 650 ft tall building with angle of twist of 30 degrees. As this has a decent deflection and a lower amount of CO2e released.
Note: the deflections calculated seem a bit small and should not be taken to be exactly accurate. To get more accurate results a more in depth study would need to be completed. There is definitely room for improvement with this model for the future.