We all want to make our buildings more efficient and reliable. Artificial solutions abound, but evolution also holds the answers to many of our problems.
Some animals and plants ingeniously adapt their bodies to environmental conditions like light, temperature and air quality by changing colour or filtering out harmful gases. A branch of scientific research, known as biomimicry, copies and adapts these natural solutions, and applies them to design and engineering.
This approach has already yielded many success stories, from Japan’s Shinkansen bullet train, to swimsuits inspired by shark skin and robots modelled on insects, to name just a few. It also has a wide range of applications in architecture, building services, and even city-wide air quality sensors.
Research in biomimicry requires more than just knowledge of biology. Researchers have to visualise creative solutions to everyday problems, while also applying rigorous scientific methodology to ensure that they actually work. Here are four promising examples of biomimicry’s potential in the near future.
Chameleon grasshoppers
Like many invertebrates, the Chameleon grasshopper (Kosciuscola tristis) has no control over its body temperature, but it does have one very special feature: at 15°C its exterior becomes very dark, almost black, and when its body temperature rises above 25°C, it takes on a turquoise-blue hue. This colour change is automatic, and happens independently of other factors like metabolism. It even occurs for some time in dead specimens.
There is also evidence that when different parts of the body are different temperatures, they might also change colour independently. By taking inspiration from this grasshopper, we could design chromatic sensors that report the temperature and/or radiation absorbed by surfaces. We could also design coatings – for windows and other exterior surfaces – with variable reflectivity for passive thermal control.
Silkworm cocoons filter out CO₂
Silkworm cocoons (Bombyx mori) allow some gases that are harmful to the development of the larva, such as CO₂, to leave the cocoon structure both quickly and steadily. However, other non-hazardous gases, such as oxygen, can pass in both directions. The caterpillar has also been observed to maintain a constant internal temperature, even when exposed to extreme environmental changes.
In addition, research has found that an electric current modulated by temperature is generated when the cocoon absorbs moisture. By combining these properties, we could use organic materials to create very sensitive, self-powered CO₂ sensors.
Desert iguanas turn pale in the sun
The Desert iguana (Dipsosaurus dorsalis) lives in the Colorado desert and areas of Southern California (USA) and Baja California (Mexico). It faces extreme temperatures of over 48°C during the day, with temperatures often plummeting by 40°C at night.
Though cold-blooded, its ideal body temperature is 38.5°C, but it can live and perform most of its vital functions within a range of 5°C above or below this point. To regulate its temperature, its body lightens as the temperature increases.
Desert iguanas also have black patches on their skin. Though their purpose is not completely clear, it is thought that these may help to protect against certain types of harmful solar radiation. Biomimicry can be used to develop colour sensors, including materials and/or facades that change colour depending on the temperature of the environment.
Air-purifying plants
Plants can act as a filtering and air-cleaning system, absorbing CO₂ and releasing oxygen. There is evidence that the implementation of green infrastructure, such as green roofs and green walls, not only improves air quality in urban environments, but also contributes to the reduction of heat islands .
As well as filtering CO₂, some plants are sensitive to other types of pollutants, such as ozone, which can show up as white or light spots on the top of the leaves. The presence of sulfur (SOx) and nitrogen oxides (NOx) in the air can also cause a change in leaf colour due to loss of chlorophyll and holes in the leaves. This is a clear example of how plants are not only a source of inspiration for air pollution sensors – they are sensors in and of themselves.
Designing the future
These examples offer just a small glimpse of what biomimicry can offer, but they show that it goes far beyond an aesthetic or superficial design component. It is a practice that encourages us to rethink how we can approach problems in innovative ways, drawing inspiration from nature.
While we have focused here on optimising or reconfiguring energy systems in buildings, biomimicry can be applied in many other fields. As well as being a powerful intellectual tool for the future, its very existence underscores the importance of interdisciplinary collaboration in scientific research.
