Sustainable Construction: Transparent Metamaterial as the Key to Energy Saving

How will we build in the future? Sustainability, energy efficiency and comfort are key requirements that modern materials must fulfil. Conventional building materials such as glass are reaching their limits – for example when it comes to protecting against glare or overheating. This is where a new polymer-based material comes in, intelligently combining natural lighting and heat regulation to reduce energy consumption.

In an interview with K-Mag, Dr Gan Huang talks about the development of this multifunctional material, its special properties and potential applications in architecture and beyond.

Dr Huang, what was the motivation behind the development of the new polymer-based material and what problems was it intended to solve?

Dr Gan Huang: We wanted to address several issues associated with traditional transparent roofs and walls for buildings, such as glare, privacy concerns, and overheating. These problems can make indoor environments uncomfortable, increase energy consumption for cooling, and reduce productivity. Our goal was to create a material that not only allows natural light to enter buildings but also manages light and heat in a way that enhances indoor comfort, reduces energy use, and improves occupant well-being.

Can you explain the special properties of your newly developed material?

Huang: The Polymer-based Micro-Photonic Multi-Functional Metamaterial (PMMM) diffuses 73% of incident sunlight, which reduces glare and provides a more comfortable indoor lighting environment. The material allows 95% of visible light to pass through, which is higher than traditional glass. Additionally, the material has a high emissivity (~0.98) in the mid-infrared range, enabling it to passively radiate heat and cool buildings without consuming electricity. Its superhydrophobic properties with a contact angle of 152° help in keeping the surface clean by repelling water and dust.

To what extent does the material enable more sustainable construction?

Huang: By reducing the need for artificial lighting and minimizing the use of air conditioning, it lowers the overall energy consumption of buildings. The material helps maintain a comfortable indoor temperature, reducing the reliance on air conditioning systems. Its self-cleaning properties reduce the need for frequent cleaning and maintenance, which can save resources and costs over time. Made from commercially available and environmentally safe polymers, the material can be produced on a large scale without significant environmental impact, contributing to more sustainable building practices.

What practical applications do you see for it?

Huang: We see a wide range of applications for the PMMM. In building construction, it can be used in roofs and walls to improve natural lighting and thermal comfort in residential and commercial buildings. In greenhouses, enhancing light diffusion and photosynthesis can improve plant growth and yield. In the automotive industry, it can be applied to car windows and sunroofs to reduce glare and heat, improving passenger comfort.

What were the challenges in developing this material and how were they overcome?

Huang: One major challenge was material selection; we needed to find a polymer that was not only transparent and durable but also had high emissivity in the mid-infrared range. Polydimethylsiloxane met these requirements. Fabrication was another challenge, as creating the micro-pyramid structures required precise photolithography and etching techniques. We optimized these processes to ensure consistent and scalable production. Extensive testing was needed to confirm the material's properties and performance, so we conducted both laboratory and outdoor tests to validate our results.

How could the new material be integrated into existing construction and urban development projects?

Huang: The material can be applied to existing glass structures as a film or coating to enhance their performance. For new constructions, it can be used as part of the initial design for new buildings, replacing traditional glass in windows, roofs, and walls. Additionally, the PMMM can be manufactured in modular panels that can be easily installed in a variety of building types and styles, making it a versatile solution for different construction needs.

What role could polymer-based materials play in the construction of the future?

Huang: Polymer-based materials like the PMMM could play a significant role in the future of construction by improving sustainability. Their energy-efficient properties can contribute to greener buildings and lower carbon footprints. By managing light and heat more effectively, they can create healthier and more comfortable indoor environments. Their versatility allows for innovative architectural designs that prioritize natural light and aesthetic appeal. Moreover, the durability and low maintenance requirements of these materials can reduce long-term costs for building owners and operators, making them a practical and cost-effective choice for future construction projects.