Nature-Inspired Architecture
Elevating Green Building Performance through Biomimicry
by Chasity Johnson, Product Manager, Sto Corp.
(Editor’s Note: With over six years of experience in building products, including flooring, coatings, and raw materials, Chasity Johnson brings a wealth of knowledge and expertise to her role. She holds a Bachelor’s degree in Consumer and Retail Studies from The University of North Carolina at Greensboro. Leveraging her academic background and practical experience in sales and product management, Johnson drives innovation and success in her field at Sto® Corp.)
Nature offers inspiration for a wide variety of pursuits, from the fine arts and sports worlds to new ideas in improving health care and combating climate change. That’s one reason that the principle of biomimicry has emerged over the last two decades as not only an established discipline in applied science but also a preferred process for improving building performance. At its core, biomimicry looks to nature for design inspiration, uncovering innovative and sustainable solutions to human challenges by emulating time-tested patterns and strategies in biological processes.
Examples of this approach, according to the Missoula, Montana-based Biomimicry Institute, include wind-power turbines with designs based on humpback whale fins, as well as the new buildings in cities such as Harare, Zimbabwe, with internal climate control systems developed by emulating the structures of termite mounds. Another significant area of study for sustainable building design and operations has been the successful application of biomimetic microtechnologies in finish materials, sealants, and coatings.
The benefits of these and other next-generation coatings include improved baseline performance, in particular under variable climate types and enclosure functionality requirements. Green building teams have adopted the coatings as a best practice in a wide range of applications. The work underscores how biomimicry, including on the nano and micro scales, contributes to all facets of sustainability’s triple bottom line: their exteriors and varied substrates are durable and resilient, reducing the need for reapplication and saving money and time while remaining as bright and luminous as when new.
Nanotechnology studies of lotus plants in the 1990s in Bonn, Germany, led by biologist Wilhelm Barthlott, sought to determine why their leaves easily shed water and dirt. Evaluations of the leaf surface microstructures revealed an answer: the microstructures offered minimal contact area for water. Barthlott created a similar nanostructure for use in exterior paints, which offered self-cleaning characteristics unseen in other formulations, thanks to the water-repelling effects at the micro-scale. The promise of this novel class of coatings was its ability to resist water, microbes, icing, and dirt accumulation on all surfaces, not just those finished with inherently non-absorptive materials such as plastics.
The resulting coatings create surfaces that clean and dry themselves rapidly and, specified properly, can provide for years of effectiveness including on highly porous surfaces such as concrete, wood, stucco, and more. This opens doors for multiple sustainability strategies, thanks to specifiable and desirable effects possible with hydrophobic coating systems in a range of contexts. Radiant color intensity, for example, can have a longer effective life thanks to the less pronounced degradation curves of hydrophobic materials. Also valuable is the lasting ultraviolet (UV) protection and weather resistance, which can contribute to the goals of varied green-building protocols, including Passive House, LEED®, and the Living Building Challenge.
Another valuable benefit arises in the reduction in microbiological growth on building exteriors, including the algae and fungi that discolor and degrade materials over time. Building surfaces designed to shed water and dry quickly provide improved performance over those that hold moisture and water, and these fast-drying surfaces have also been adapted from those found in nature.
Writing in Frontiers in Zoology in 2010, the Swedish biologists Thomas Nørgaard and Marie Dacke summarize how Darkling beetles in the coastal desert of Southern Africa facilitate water capture from fog as they roam the ridges of the dry dunes. Using its shell and forewings, or elytra, all covered in microscopic bumps, the beetles condense water on the hydrophilic upper tips of the textured surfaces, and then the useful liquid is diverted away into the hydrophobic depressions in between. With observations like these from the uniquely adapted fog-basking beetles, application researchers have developed the technology now employed for façade paints. The coatings’ micro-formed surface textures help dry dew and rain more quickly than standard paint formulations do, again protecting against damaging microorganisms and wear while improving color retention and durability on a variety of substrates.
Another benefit of biomimicry in sustainable design is the adaptation of responsive or smart materials that activate when exposed to certain environmental stimuli, leading to enhanced performance. These active materials inspired by nature include the more effective water-shedders, which can help clean surfaces through their beading and movement and can also interact with UV radiation to improve visual characteristics, too. Employing a rapid drying coating is another way to boost the active behavior of a building surface to boost performance and sustainability.
For today’s building projects, coatings being introduced with properties that come straight from nature can add a new dimension to a building’s adaptive capacity and operational profile. Smart coatings, as they are called, are designed to protect a building against at least one of six key performance impacts: mechanical, such as hail or thermal expansion; contaminant, such as mineral or organic pollutants; biological, such as fungus or termites; water, such as humidity or rain; temperature, such as ambient or fire-related; and light, such as reflectivity and UV radiation. With these in mind, the use of biomimicry has been shown to create architectural coatings that enhance building performance in a range of ways. In addition, these biomimetic materials address the true needs of a building, not just the building codes and certification standards.
