Biomimicry: drawing inspiration from Nature for Sustainable Architecture
The growing awareness of environmental issues has deeply rooted the improvement of energy performance at the heart of the concerns of the construction industry. Faced with the challenges posed by energy consumption and greenhouse gas emissions, standards and regulations have emerged to promote the construction of high-energy-efficient buildings. In this perspective, biomimicry applied to construction represents the use of architectural techniques inspired by nature to reduce the energy consumption of buildings. In this article, we will explore two approaches that draw inspiration from fauna and flora to create sustainable and innovative solutions.
Biomimicry to maximize solar gain: the example of sunflower
Sunflowers are famous for their ability to "follow the sun," orienting themselves from east to west throughout the day. This behavior, known as heliotropism, and specifically diaheliotropism for sunflower flowers, allows them to capture the maximum amount of sunlight and heat. This natural phenomenon has inspired a practical application in the field of architecture, particularly in the case of sunflower houses. A team led by Zhijian Liu studied this approach in a house located in the Qinghai province on the Tibetan Plateau in China, at an altitude of 2,633 meters. In this area where winter temperatures range from 5°C to -20°C, the house was renovated to maximize solar gains. A fully glazed veranda was added to the south facade, serving as a buffer space between the interior of the house and the outside. Insulation was also improved. These modifications have resulted in nearly a 50% reduction in coal stove consumption, which is used for both supplemental heating and cooking. Furthermore, average indoor temperatures have significantly increased, with a 5-degree rise in the room equipped with the wood-burning stove. This nature-inspired approach demonstrates the potential benefits of biomimetic architecture in improving energy efficiency and comfort in homes.
Biomimetics to optimize ventilation: the example of termite mounds
Termite mounds, the natural habitats of termites in warm regions, have a cone-shaped structure that widens at the base and tapers towards the top. Inside these termite mounds are chimneys. This design enables a phenomenon called thermal draft, which functions as a natural ventilation driving force based on the density difference between indoor and outdoor air. Air intakes are located at the bottom of the termite mound, while outlets are found at the top. The hot air inside is thus drawn outwards through the upper vents, while the cooler outside air, cooled by the ducts, rises into the structure where the termites live. This system creates a cycle of air renewal, maintaining a constant temperature of around 30°C inside the termite mound.
This technique offers the advantage of reducing reliance on mechanical ventilation, as demonstrated by the case of the Eastgate Building, a shopping center constructed in 1996 in Harare, Zimbabwe, by architect Mick Pearce. The passive cooling of this building involves storing heat during the day and dissipating it at night when temperatures drop. At the start of the day, the building is cool, but as hours pass, heat generated by machines and occupants, along with solar gain, increases the indoor temperature. In the evening, as outdoor temperatures decrease, the hot air inside is expelled through the chimneys, aided by fans and its natural buoyancy due to its lower density. Fresh, denser air is then drawn in from the bottom of the building. This process continues throughout the night, with cold air circulating in the cavities of the floor slabs until the building reaches the ideal temperature to begin the following day.
Thanks to this passive cooling strategy, the Eastgate shopping center consumes only 10% of the energy required by a similarly sized conventionally cooled building. When utilizing active cooling, the shopping center consumes 35% less energy to maintain the same temperature as a conventionally cooled building. This innovative approach inspired by termite mounds demonstrates how nature can provide effective and sustainable solutions for energy-efficient building design.
We have explored two fascinating examples of techniques inspired by fauna and flora that influence the building envelope and allow optimization of parameters such as solar gain and ventilation, while reducing energy consumption. Biomimicry thus opens up exciting new perspectives for sustainable building design, harnessing millions of years of nature's evolution to create efficient and environmentally-friendly solutions. By embracing a biomimetic approach, we can not only improve the energy performance of buildings but also move closer to our shared goal of building a sustainable future.
Source:
Evaluating potentials of passive solar heating renovation for the energy poverty alleviation of plateau areas in developing countries: A case study in rural Qinghai-Tibet Plateau, China - Zhijian Liu et al. Solar Energy, 2019
National geographic : See How Termites Inspired a Building That Can Cool Itself | Decoder
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