Thermochromic material could make indoor temperature control more energy-efficient

Cooling off generally is a matter of life or death, but air-con — when and if available — already accounts for 7% of the world’s energy use and three% of carbon emissions. With temperatures hitting record highs and warmth waves growing more frequent worldwide, the necessity for more efficient ways to maintain indoor temperatures in check has also grown more urgent.

One solution to mitigate the difficulty involves coating windows with materials that keep heat out while still allowing light to go through. One such class of materials is thermochromics, yet existing varieties are still too expensive and short-lived to make a feasible selection to be used in buildings, vehicles and wherever else needed.

The brand new salted polymer mix system developed by Rice engineers within the Nanomaterials Laboratory led by Pulickel Ajayan overcomes these challenges, potentially enabling the large-scale deployment of thermochromics as an energy-efficient indoor space cooling technology.

“Imagine a window that becomes less transparent because the day gets warmer, keeping interiors cool without consuming energy,” said Sreehari Saju, a materials science and nanoengineering doctoral student at Rice who’s a co-lead writer on the study. “Our formulation leverages each organic and inorganic components to beat the constraints of existing thermochromic materials resembling short lifespans and high costs.

“Furthermore, this material’s thermic response is well-matched to real-world environmental demands. We expect that smart windows comprised of this material could significantly reduce energy consumption in buildings, making a tangible impact on each energy costs and carbon footprint.”

The researchers combined experimental methods with computational simulations to grasp the fabric’s behavior under different environmental and architectural settings. As an example, they assessed how the fabric would perform in specific urban areas around the globe to get a way of its potential impact when deployed at scale.

“Our approach was unique since it required a precise balance of materials and techniques that had not been previously explored in this mixture, offering a brand new pathway for developing smart materials,” said Anand Puthirath, a research scientist within the Ajayan research group and co-lead writer on the study. “We conducted comprehensive experiments to characterize the properties of the fabric, as well environmental stability and sturdiness testing, showing that our mix can outperform existing thermochromics.”

The researchers synthesized the fabric by mixing two polymers with a style of salt and worked on optimizing the composition to realize smooth transitions between transparent and opaque states with temperature fluctuations. Their findings show that the brand new thermochromic mix shouldn’t be only highly effective in regulating solar radiation but additionally remarkably durable with an estimated lifespan of 60 years.

“These research findings set recent benchmarks in thermochromics’ durability and performance and particularly in an easy practically viable system,” said Ajayan, the corresponding writer on the study and Rice’s Benjamin M. and Mary Greenwood Anderson Professor of Engineering and professor and department chair of materials science and nanoengineering. “Our work addresses a critical challenge in sustainable architecture, offering a practical and scalable solution for enhancing energy efficiency in buildings.”

The thermochromic behavior of the fabric was studied in collaboration with Professor Yi Long and her doctoral student, Shancheng Wang, from the Department of Electronic Engineering on the Chinese University of Hong Kong, Sha Tin.