Protect Indoors From Heat By Building Zigzag Patters On Exterior Walls

Structural engineers have made an intriguing discovery: apartment buildings constructed with angled, shark-fin-shaped protrusions on the side that receives the most sunlight can remain cooler, even during the hottest days. This innovative design offers a solution for cooling buildings in a world where extreme temperatures during July and August are becoming the norm. As the global climate continues to warm, architects and engineers are revisiting building techniques that use simple, cost-effective design elements to combat heat without heavy reliance on air conditioning systems.

This discovery is part of a broader movement to incorporate passive cooling strategies into building designs. Historically, humans have developed ingenious ways to create structures that take advantage of thermodynamics, using natural air circulation to keep them cooler. From ancient Roman amphitheaters to the wind towers of Yazd, Iran, civilizations across the globe have long implemented architectural features that help control indoor temperatures. However, much of that knowledge was sidelined with the advent of modern building techniques, which favored more standardized, box-like structures that exposed homes to the full force of environmental elements, including heat.

In the face of escalating global temperatures, researchers from Purdue University and Columbia University teamed up to explore new ways to retrofit these modern, boxy structures to help them stay cool without significantly increasing energy consumption. Their research identified two main sources of heat for urban buildings: direct sunlight and the ground. Urban environments, with their abundance of cement and asphalt, absorb heat during the day, releasing it back into the atmosphere and exacerbating already warm temperatures around buildings.

“Heat affects buildings from two directions,” explained Qilong Cheng, a postdoctoral researcher at Purdue University. “From the sky, we have the sun’s direct heat, while the ground absorbs and radiates heat upward throughout the day. This creates a complex challenge, especially in cities where the heat island effect is so strong.”

To address this dual heat assault, Cheng and his colleagues devised a two-surface zigzag design, with one surface facing upward toward the sky and the other toward the ground. Resembling the sawtooth roofs of older factory buildings, the angles of these protrusions play a vital role in deflecting heat. The research found that this angled, shark-fin design could reduce indoor temperatures by an impressive 5.5°F, creating a noticeable difference in comfort without the need for additional energy usage.

The researchers further optimized the design by incorporating different materials for each surface. Ultra-white paint, which has been proven to reflect sunlight effectively, was used on the upper surfaces to bounce solar radiation away from the building. Meanwhile, ground-facing surfaces were covered in materials specifically chosen to either reduce or deflect heat radiating up from the ground.

“In urban areas, pavement and asphalt can significantly increase surrounding temperatures,” Cheng added. “This two-angle design helps mitigate both the upward radiation from the ground and direct heat from the sun.”

The team’s study didn’t stop at proving the concept—Cheng and his colleagues are now working to turn this design into a commercially viable product. One promising material identified in the study was corrugated iron, which is relatively inexpensive and easy to work with. Corrugated iron could also help reduce energy usage for heating, ventilation, and air conditioning (HVAC) systems by as much as 14%, further enhancing the overall energy efficiency of buildings.

In an era when energy conservation and sustainable design are more important than ever, the significance of such simple, effective strategies cannot be overstated. Cities around the world are grappling with the dual challenges of rising temperatures and energy demands. The prospect of retrofitting existing buildings with these shark-fin protrusions offers a relatively low-cost, scalable solution that could help address both issues simultaneously.

As Cheng and his colleagues move toward patenting and commercializing the design, they hope to see it adopted widely. “With so many existing buildings in urban areas, retrofitting is a practical and cost-effective way to make a significant impact on energy usage and comfort,” Cheng emphasized.

This research exemplifies how modern science can combine with time-tested architectural principles to address the pressing needs of a warming world. While air conditioning systems provide immediate relief from the heat, passive cooling strategies like these offer a more sustainable, long-term solution that could dramatically reduce energy consumption while enhancing indoor comfort. With growing interest in energy-efficient building designs, this zigzag, shark-fin innovation could be a critical step forward in urban planning for the future.