Around the world, climate change and architecture are turning cities into ovens. Higher-than-average temperatures — combined with heat-absorbing infrastructure such as concrete, asphalt, steel and glass — can cause a dangerous phenomenon called the heat island effect. Using air conditioning only exacerbates the problem. From Albuquerque, New Mexico, to Zeehan, Western Australia, urban areas record summertime temperatures that are 10 to 20 degrees Fahrenheit (oF) hotter than the surrounding countryside. As global temperatures continue to rise, tens of thousands of people could die each year from heat-related causes alone, according to the World Health Organization.
Fortunately, the future of architecture is taking on a cool change. Dozens of innovative building and urban designs, many of which take their cues from ancient civilizations and biological systems, are reaching maturity — and they could help keep local temperatures down while using less energy overall. From passive techniques that capitalize on shade and evaporative cooling to creative innovations inspired by insects, sources of creativity seem endless.
Climate Change and Architecture
Reducing the urban heat island effect starts with cooling individual buildings. Air conditioners may seem like an easy solution, but these relatively small appliances consume tens of thousands of megawatts of electricity globally. Researchers estimate that by 2050, more than 4.5 billion AC units will be in use, eating up 13% of the world’s electricity and producing 2 billion tons of carbon dioxide annually, reports The Guardian. Employing passive cooling techniques could keep buildings comfortable without a heavy carbon footprint.
In India, architects Manit Rastogi and Sonali Rastogi, who founded the firm Morphogenesis, have demonstrated an intriguing model that draws from the past. For the Pearl Academy of Fashion headquarters in Jaipur, a city of 3 million in northwest India, the architects used centuries-old architectural techniques to keep this modern building cool, reports Treehugger. They clad the exterior in a lattice screen set 4 feet away from the exterior wall. The outside layer, reminiscent of a traditional jaali, acts as a thermal buffer. Architects designed the building to be raised above a vast pool of water. The pool was inspired by ancient stepwells that date back to between 200 and 400 A.D. It acts as a thermal sink and provides evaporative cooling to the structure above. Together, these techniques keep the academy 20 oF cooler than the outside air.
Most people look upon termites with scorn. These insects are known for burrowing into wood and eating homes from the inside out. But termites are accomplished engineers. In the sweltering deserts of Africa, Australia and South America, colonies build giant, naturally cooled towers of mud that, when dry, maintain a comfortable temperature inside, even when it’s well over 100 oF outside.
Zimbabwean architect Mick Pearce took inspiration from these crafty critters, reports National Geographic. He found that termite towers, usually between 20 and 40 feet tall, are all built with a skinny, boat-shaped footprint that narrows at the top. These structures always face north-to-south, which exposes the widest part to the sun during the coolness of dawn and dusk and shows little surface to the sun when it’s overhead. Strategically placed pores and a chimney-like structure allow air to pass up from the cool depths, venting warm air out the top.
Pearce borrowed from the termites when designing a building called Eastgate in Zimbabwe’s capital city, Harare. It’s made from brick and concrete — materials that can absorb a lot of the sun’s heat without rising much in temperature. Exterior grooves along with hundreds of small rectangular shapes greatly increase the surface area, which reduces the building’s ability to retain daytime heat and improves its ability to quickly shed heat at night. Airways at the base of the structure pull in cool air and circulate it upward through the building, where it warms and then vents through chimneys. Temperatures inside the building hover around 82 oF during the day, no matter what the thermometer says outside, and drop to 57 oF at night. Pearce has employed biomimicry architecture for several other buildings and continues to improve on his designs.
Cooling Urban Streets
Reducing the heat of individual buildings is a step in the right direction. Coupled with innovations in street design, urban architecture can transform a concrete jungle into a cool oasis. Recently, Abu Dhabi, capital of the United Arab Emirates and one of the hottest cities on the planet, sponsored a global design competition encouraging creative ideas that could counter the urban heat island effect. More than 300 entries submitted from teams in 67 different countries offered cooling solutions for a city where summertime temperatures regularly exceed 100 oF for extended periods of time. Ten winning entries, announced in October 2020, each received $10,000 in prize money.
Their results were stunning, reports Arch Daily. A palm tree-inspired concept titled “The Oasys” combines structures shaped like 30-foot palm leaves with real trees. The towering leaves provide shade and are also solar powered to run misters for pedestrians and landscaping below. A proposal, titled “Sa’af Al-Nakheel,” envisions a multilayered courtyard featuring gardens, canopies and vertical walls interwoven with dried palm fronds to produce a dappled shade. The misters would also keep things comfortable through evaporative cooling. “Circadian Clouds” imagines a large, airborne shade structure that floats overhead. Made of dozens of individual geodesic globes, each would reflect sunlight by day, illuminate the space at night and together become a public art element.
But climate change and architecture can come together in less whimsical ways. Yale Environment 360 points to the many efforts around the world increasing the reflectivity of rooftops by painting them white or incorporating reflective materials into roofing materials. A new kind of coating developed by researchers at Columbia University contains tiny pores that reflect 96%-99% of all wavelengths of sunlight and, when applied to the exterior of buildings, cools them down, reports Smithsonian Magazine. Even a solution as simple as covering a building with ivy can lower local temperatures and relative humidity, according to House Beautiful.
In a world faced with the inevitable rise of global temperatures, the future of architecture demands innovations to cool cities. Looking to the past nature and to solutions already found in nature could give architects the tools and inspiration they need to turn down the heat.
Author: Tracy Staedter
Published in NOW magazine – Northrop Grumman, July 2021