Fascinating, isn’t it? The latest, greatest idea to hit the ‘green movement’ – and it’s borrowed from termites. Lund University just released a study stating that we can emulate the climate control used by termites in their mounds to create climate-smart buildings with a greater energy efficiency and a negligible carbon dioxide footprint.

These termite mounds are lauded for their sophisticated ventilation systems that supposedly regulate temperature and humidity. David Andréen, senior lecturer at the Department of Architecture and Built Environment at Lund University, waxes eloquent about the digitalisation of design, biological systems, and how they

provide an important model for how we can best utilise these possibilities.

https://www.eurekalert.org/news-releases/994749

According to the research published in Frontiers in Materials, the interiors of termite mounds consist of interconnected channels, tunnels, and air chambers. These are believed to capture wind energy for respiration – or exchanging oxygen and carbon dioxide with the environment. The researchers suggest that similar structures could be integrated into building walls to facilitate a new method of controlling airflow, heat, and moisture.

Andréen introduces the concept of creating climate-smart buildings by developing turbulent, dynamic, and variable systems. These systems would require minor energy provision and could be controlled by very small equipment. The control of these systems would only necessitate electronic control,

“without using mechanical components such as fans, valves.”

https://www.eurekalert.org/news-releases/994749

The research team evidently demonstrated how airflow interacts with geometry – how the parameters in a structure cause flows to arise and how these flows can be selectively regulated. Andréen suggests that this system could be a prerequisite for a

distributed system in which many small sensors and regulating devices are placed in the climate-adaptive building envelope through miniaturisation, durability/sustainability and cost reduction.

https://www.eurekalert.org/news-releases/994749

At this point, it must be asked: Can these principles really be applied to human architecture in a meaningful, scalable, and cost-effective manner? The report casually suggests that this revolution in architecture would be possible only with complex internal geometries achieved via 3D printing. Has anyone accounted for the resource requirements, carbon footprint, and scalability of such an approach? In light of these questions, one can’t help but recall a similar time when “bio-inspired” design led to a spate of buildings shaped like pinecones and seashells, with little to no practical benefits or sustainability improvements.

Andréen concludes with an almost reverent admiration for the termites’ “building process” that results in “extremely complex well-functioning ‘engineering masterpieces'” without centralised control or drawings. Well, insects they might be, but one must remember that termites have been around for millions of years, fine-tuning their constructions to their specific needs and environment, without the constraints of urban planning regulations, building codes, or market forces.

While the concept itself is intriguing, one must not forget to take into account the inherent complexities and realities of human architecture and urban development before crowning termites as our architectural messiahs. Until these climate-smart designs can demonstrate their viability in real-world applications – scaled up from termite-sized mounds to human-sized buildings, accounting for the myriad of regulations, cost considerations, and human comfort needs – one might take this research with a grain of sand… or should we say, a piece of wood?

Source: Lund University. “Climate-friendly air conditioning inspired by termites.” Lund University News, 2023. DOI: 10.3389/fmats.2023.1126974.

It’s an open access article if you wish go read it.

Termite-inspired metamaterials for flow-active building envelopes

David Andréen¹* and Rupert Soar²

• ¹BioDigital Matter, Department of Architecture and Built Environment, Lund University, Lund, Sweden
• ²School of Architecture, Design, and the Built Environment, Nottingham Trent University, Nottingham, United Kingdom

In this article we investigate the performative potential of reticulated tunnel networks to act as drivers for selective airflows in building envelopes and thereby facilitate semi-passive climate regulation. We explore whether such transient flow can be used to create functionally graded metamaterials in bio-inspired, additively fabricated buildings. The tunnel networks are modelled on the egress complex found in the mound of certain macrotermite species. The hypothesis we explore is that oscillating airflow of low amplitude can be used to generate large scale turbulence within the network and thereby increase the mass transfer rates across the network. The hypothesis is tested through a series of 3-dimensional and 2-dimensional experiments where various geometries are exposed to a forced oscillation of the air or water column. The results are evaluated in the 3-dimesional experiments through tracer gas measurements, and in the 2-dimenstional experiments through visual qualitative assessment using fluorescein dye. We find that the oscillating fluid gives rise to large scale turbulence that causes a net mass transport across the tunnel network, and that this turbulence occurs when certain combinations of amplitude, frequency, and network geometry are achieved. Furthermore, we conclude that the net mass transfer is large enough to be functionally useful in a building envelope as a method to regulate either building interior climate or the envelope’s own microclimate.

1 Introduction

Emerging technologies in additive fabrication and computational design are opening up radical new possibilities for performative building envelopes, where intricate and (micro)site-specific geometries can enable the creation of functionally graded metamaterials (Soar and Andréen, 2012). Metamaterials are materials shaped in ways that give them properties not exhibited in their naturally occurring conditions. They have long been a concept meaningful primarily in small-scale, high-value engineering such as electronics or more recently mechanical engineering. However, with the emergence of additive fabrication technologies capable of producing complex geometries even at large volumes (current state-of-the-art powder bed printers can produce objects up to 8 cubic meters overnight, with exceptionally high resolution), there is a growing opportunity to implement these concepts in the construction industry.

In this paper we explore how such functionally graded metamaterials can potentially be modelled on the structures found in termite mounds. The large mound structures are created by termites to act as physiological organs that, through their complex and functional internal geometry, regulate significant flows of respiratory gases and maintain an internal microclimate with steep gradients in humidity and temperature towards the outside (Heyde et al., 2021). They gain their function primarily from geometry and can adapt to a surprising range of surrounding environments. Biological systems exhibit a strong coherence between form and function, and are able to draw benefits from highly complex and specific form. They can serve as a model not only for the direct relationship between form and performance, but also for the generative processes that enable organisms to produce such structures (Andréen and Goidea, 2022; Goidea et al., 2022).

The hypothesis tested in this paper is that the tunnel network found in the envelope of the mound can, when activated by transient air movements, generate a useful and controllable mass transport across the envelope. If such a flow can be selectively created within and across a permeable structure, it may provide a useful tool for semi-passive regulation of building climates and building envelope microclimates. The ambition of the paper is to provide a proof-of-concept for previously undocumented mechanisms and establish what geometric parameters can be used to control the effects.

https://www.frontiersin.org/articles/10.3389/fmats.2023.1126974/full

Citation: Andréen D and Soar R (2023) Termite-inspired metamaterials for flow-active building envelopes. Front. Mater. 10:1126974. doi: 10.3389/fmats.2023.1126974

Copyright © 2023 Andréen and Soar. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.