Fungi-Based Façade Could Slash Cooling Energy Use in Buildings by Half
- Marc Violo
- 3 hours ago
- 3 min read
Too long to read? Go for the highlights below.
Researchers have reimagined the traditional South Asian jaali screen using mycelium-based composites, creating a bio-based façade system called the bio-jaali.
Dynamic building energy simulations for New Delhi show the bio-jaali can reduce peak indoor temperatures by up to 14.8°C and cut annual cooling energy demand by more than 50%.
The material absorbs up to 17.2% of its weight in moisture while remaining dimensionally stable, enabling passive evaporative cooling without mechanical intervention.
An Ancient Architectural Idea, Reconsidered in Biological Terms
South Asian cities have long grappled with heat. For centuries, builders responded with the jaali—an ornately perforated stone or timber screen that shades interiors, channels airflow, and reduces the felt temperature of a room without consuming a watt of electricity. It is a quietly elegant solution that predates air conditioning by millennia.
Today, those cities face a problem of a different scale. New Delhi, like many South Asian megacities, has recorded a 60% increase in so-called "danger-level" heat-stress hours over the 28 years to 2019, according to climate data analysed in a new study published in Energy and Buildings. Meanwhile, the reflexive response, installing more air conditioning,accelerates the very emissions driving the heat. It is a feedback loop that is difficult to break with conventional materials.
A team of researchers at Newcastle University, led by Kumar Biswajit Debnath and colleagues including Natalia Pynirtzi, Jane Scott, Colin Davie, and Ben Bridgens, has proposed a way to break it. Their concept, called the bio-jaali, replaces traditional sandstone with mycelium-based composites (MBCs)—a material grown by cultivating fungal root networks through agricultural waste. The result is a lightweight, biodegradable panel that can be formed into the intricate geometries a jaali demands.
What Mycelium Brings to the Wall
Mycelium, the thread-like root structure of fungi, can be grown into rigid composite panels by colonising a substrate such as crop residue or sawdust. Once heat-treated to halt growth, the material becomes structurally stable. The broader potential of such mycelium-based materials for construction has attracted growing research interest, and this study adds a specific and quantifiable claim to that body of work.
The key property here is hygroscopicity, the ability to absorb and release moisture. The MBC panels tested by the Newcastle team absorbed up to 17.2% of their own weight in moisture during cyclic humidity tests, while their physical dimensions changed by less than 3%. That stability matters. A material that swells and warps under humid conditions cannot reliably serve as a façade element. The fact that MBCs passed this test suggests they are genuinely suited to the hot, seasonally humid climate of northern India.
That moisture absorption also drives evaporative cooling. As water evaporates from the panel surface, it removes heat from the surrounding air—the same principle that makes a damp cloth feel cool. In a façade application, this translates into a passive cooling effect that requires no energy input.
Simulating the Impact on a Delhi Building
To move beyond laboratory data, the team conducted dynamic building energy simulations using historical climate data for New Delhi spanning 1991 to 2019. The simulations compared a conventional glazed façade against the bio-jaali system and yielded striking results.
Replacing the standard façade with the bio-jaali reduced the annual average indoor operative temperature by 3.5°C, a 10% improvement, while peak summer indoor temperatures fell by up to 14.8°C. Annual cooling energy demand dropped by 50.4%. For a city where air conditioning load is rising sharply and grid electricity remains partially coal-dependent, that figure carries meaningful implications for both household energy bills and national carbon targets.
The researchers frame this as a contribution to what they term "bio-building physics", a nascent field in which biological materials actively regulate indoor climates rather than passively resisting heat transfer. Unlike static insulation, mycelium composites used as building envelopes can respond dynamically to ambient humidity, cycling between absorption and release as conditions change.
This approach also connects to a wider movement in sustainable architecture that treats bio-based materials not merely as lower-carbon substitutes, but as components capable of contributing actively to thermal performance.
The bio-jaali remains a proof of concept. Scaling production, ensuring consistent material quality, and weathering real-world monsoon seasons are all challenges that field deployment would need to address. But as a demonstration that vernacular design intelligence and modern biotechnology can reinforce one another, the research makes a compelling case. The jaali survived for centuries because it worked. Its biological successor may have the same advantage.
