EVALUATE YOUR ALTERNATIVE

Summary Table

For 2 or More Units: Create Two New Evaluator Nodes

In Dynamo, I created two custom evaluation metrics—Cost Estimation and Directivity—to assess building form performance. The Cost Estimation node calculates the total estimated cost based on inputs such as Gross Floor Area (FA) and construction assumptions, forming the basis for further financial evaluations like Cost per Square Foot of Floor Area and Cost per Square Foot of Surface Area. The Directivity metric measures geometric deviation (e.g., twist or rotation), informing derived metrics such as Twist Density and Twist-to-Height Ratio. These two foundational metrics contribute to broader performance indicators including Envelope Cost Efficiency, Spatial Efficiency, Vertical Space Utilization, and Embodied Carbon Intensity. Collectively, the evaluation framework provides a comprehensive, multi-dimensional analysis across structural, economic, spatial, and environmental dimensions. Core parameters like Top Height, Twist, Gross Floor Area, and Gross Surface Area help quantify form scale and complexity, while derived metrics such as the FA/SA Ratio and Embodied Carbon Intensity enable meaningful comparisons of design alternatives. This integrated system supports informed, data-driven decision-making in the early stages of building design.

• Images showing the node logic in your new evaluator nodes

• Cost Estimation Custom Node

• Directivity Custom Node

The new metrics introduced are

• Cost Efficiency: Cost per square foot of usable floor area. Lower values mean better economic use of space.
• Envelope Cost Efficiency: Cost per square foot of building surface. Lower values indicate a more compact, cost-effective envelope.
• Spatial Efficiency (FA/SA): Ratio of floor area to surface area. Higher values mean more usable space with less envelope, improving efficiency.
• Vertical Space Utilization: Floor area per foot of building height. Higher values show better use of vertical space.
• Twist Density: Twist angle divided by building height. Higher values mean tighter twisting, which can enhance aesthetics but may increase cost.
• Embodied Carbon Intensity: Total carbon emissions from the structure (SA × 30 kg CO₂e/ft² assuming steel/concrete). Lower values are better for sustainability.

The 250 ft height, 75° twist design was selected as the best option because it optimally balances architectural form, cost-efficiency, and sustainability. It meets the required floor area target of 2.5–3 million ft² while staying well below the site height limit of 755 ft. This design achieves the lowest embodied carbon intensity (22.04 million kg CO₂e) among all options, indicating excellent environmental performance. It also offers the lowest cost per square foot of floor area ($639.96) and the most efficient envelope cost among the 250 ft designs, reflecting minimized surface area and construction cost. Although its spatial efficiency is slightly lower than some other options, it compensates with superior envelope compactness, cost-effectiveness, and strong vertical space utilization. The high twist density (0.3) contributes to potential solar insolation benefits while maintaining structural and material efficiency. Overall, this design delivers an optimal blend of performance metrics, making it the most balanced and sustainable choice.