Journal Entry For
Module 6 - Evaluate Your Alternatives
Link to Student
For 2 or More Units: Create Two New Evaluator Nodes
Top Height [ft] | Base Radius | Gross Floor Area | Gross Surface Area | Cumulative Insolation [Wh/m2] | cost savings / yr | construction cost |
600 | 150 | 2945067 | 631087.5 | 1.02E+10 | $43,947,103 | $1,470,000,000 |
600 | 180 | 3229181 | 673101.5 | 1.02E+10 | $43,937,479 | $1,610,000,000 |
700 | 150 | 2512669 | 617080 | 4.96E+10 | $214,000,000 | $1,260,000,000 |
700 | 180 | 2760280 | 659176.2 | 4.96E+10 | $214,000,000 | $1,380,000,000 |
- Custom nodes
- PV Solar Analysis
- I started by finding the total insolation on the roof. There was a bug in the starting custom node, BuildingForm.SelectRoofSurfaces, where it would return all surface except the ground surface. I fixed this bug by only returning the last element in the surfaces list, which represented the roof.
- I used the following formulas to calculate the cost savings:
- I used the following assumptions:
- usableRoofFraction = 0.70
- pvEfficiency = 0.20
- performanceRatio = 0.80
- electricityRate = 0.12
- Construction Cost
- I made a custom node to calculate the construction cost. Since I constrained the height to be less than 750 ft, the cost per square foot is $500. I took the total floor area and multiplied it by $500/sqft.
- I integrated both custom nodes into a custom testing node, where 2 parameters could vary at a time. As in Module 5, I varied the top height and the base radius.
pvEnergy_kWh = avgInsolation_WhPerM2 * usableRoofArea_m2 * pvEfficiency * performanceRatio *365/ 1000;
costSavings = pvEnergy_kWh * electricityRate;
In this exercise, I wanted to show that even though the construction cost of the building is very high, there is potential for cost savings by adding solar PV panels to the roof.
💡Point to Ponder: 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?
- Yes, the metrics I calculated capture meaningful differences between building alternatives because they show how altering the geometry can lead to higher or lower construction costs yet also lead to savings when there is larger roof area. It may also be useful to calculate the expected energy load on the building to show the extent to which the building is energy independent.
For 3 or More Units: Develop a Single-Objective Optimization Scheme
- Brief descriptions outlining:
- Your Single-Objective Optimization scheme (combination/comparison/ranking approach)
- function:
- F = A*normalized[(construction cost - pv savings)] + B*normalized[(gross surface area/ gross floor area)]
- A and B are weightings
- minimize(F)
- It is ideal to maximize gross floor area:gross surface area, but since the scheme will minimize F, we invert the ratio.
- Cost will be minimized. PV savings is a function of insolation, so it accounts for the objective of maximizing insolation.
- One tradeoff would be that a compact building form usually has a lower surface area to floor area ratio, which is good for energy efficiency and cost. But a compact form may also have less roof surface area available for PV, which can reduce solar savings.
- I set A = .7 and B = .3, since a developer would likely care more about the cost than the slenderness of the building. However, both objectives are interlinked since a more efficient design can have lower capital costs.
- An Image/screenshot of your summary table (created in Word, Excel, Google Sheets, or any data table tool) showing the input values tested and the values computed for each of the reported parameters.
- Be sure to highlight your top 3 recommended design alternatives (for either one the example building forms or the new building form that you designed) and recommend the one design that you consider to be the “best”.
- An explanation of why you consider the recommended building form to be the “best” choice
- For 4 Units: Visualize the Recommended Alternative
- Images/screenshots showing the recommended building form based on your evaluation and analysis.
- If created in Revit or Grasshopper, show the panelized building form with visual feedback showing how your panels reflect one of the evaluations computed for the panels.
- If created in Autodesk Forma, share images/screenshots showing the results of the Daylight, Wind, and Solar Energy analysis.
- Your answers to the Points to Ponder questions for each stage of the assignment that you completed.