If the weather is too hot, just put this on them and the problem will be solved!

When we sense the outside world's temperature, we will maintain our body temperature by adding or removing clothing. Did you know that not only humans can do this, but also intelligent building materials can achieve "taking off a layer" and "putting on a layer" to maintain a constant temperature in buildings under low energy consumption conditions? Let's take a look at how it is achieved!

Building complex. Copyright image. Reprinting and using may cause copyright disputes.

01

New "chameleon" building materials emerge

Using knowledge of electrochemistry and optics, researchers have cleverly designed an intelligent building material that can undergo chemical reactions according to changes in external temperature to change its color to release or absorb energy, just like a "chameleon."

The material contains layers that can transform between solid and liquid phases. They are solid copper that can retain infrared energy to increase the temperature, and an electrolyte aqueous solution that can emit infrared rays to lower the temperature.

When the temperature around the material changes, applying a small amount of electricity to the material can cause chemical changes in the metal particles, thereby regulating the deposition morphology of nanoparticles inside the material, and ultimately changing the material's emissivity to infrared thermal radiation to achieve temperature regulation.

Schematic diagram of material color change. Image source: Reference [1]

In the hot summer, this building material can release more than 90% of infrared heat to reduce the temperature inside the building ; in the cold winter, it will only emit no more than 10% of infrared heat to maintain the temperature inside the building . The amount of electricity required during this change is extremely low, which can save about 8% of heating energy consumption. With this material, we can reduce the inconvenience caused by sudden weather changes to a certain extent.

At present, the research team has only developed material fragments no more than 10 cm wide. The assembly, commercialization and better methods of manufacturing materials are still under continuous exploration. It is believed that the advent of the era of smart materials will make greater contributions to a sustainable future.

Material fragments. Image source: Reference 1

02

What other energy-saving and environmentally friendly building materials are there?

In addition to the "chameleon" materials mentioned above, many energy-saving and environmentally friendly building materials are used in today's construction, including both artificial and natural materials. Let's take a look at what they are.

1. Energy-saving glass

Glass occupies a large area in buildings, and the energy lost through glass can reach 50% of the energy consumption of the entire building . In summer, strong solar radiation generated by the scorching sun will pass through the glass to increase the indoor temperature, and in winter, the indoor heat can be released to the outside through the glass. It can be seen that the use of energy-saving temperature-control glass is very important.

A variety of intelligent temperature-control glass has entered the market. Photochromic glass made by adding special materials to the glass will change color when exposed to sunlight, thereby affecting the light transmittance to achieve indoor temperature control.

The hollow glass made by bonding multiple pieces of glass to an aluminum alloy frame using a high-strength adhesive has a good heat-insulating effect and the indoor temperature can be well maintained in winter.

In addition, coating the glass with films with different functions can also realize intelligent control of light transmission and reflection, which can effectively increase indoor heat energy. Glass with multiple functions such as low radiation and heat reflection is emerging in an endless stream, which greatly helps energy conservation and emission reduction.

Energy-saving glass. Copyrighted images from the gallery. Reproduction and use may lead to copyright disputes.

2. High-performance concrete

Concrete is the most commonly used building material. The use of high-performance concrete saves a lot of cement and steel, and further reduces the emission of harmful substances such as carbon dioxide.

A variety of functional substances have also been added to concrete, such as titanium dioxide, which can absorb harmful substances in the air. In addition, researchers have developed cement mixtures containing phosphorescent materials to replace traditional concrete. This material absorbs sunlight during the day and can illuminate at night, thereby achieving energy saving.

Phosphorescent concrete absorbs light during the day and glows at night. Image credit: ArchDaily

3. Bamboo

Bamboo is a natural organic polymer, mainly composed of thin-walled cells and vascular bundles. Bamboo has strong impact resistance and earthquake resistance, and its internal cavity structure makes its heat conduction efficiency much lower than that of concrete. The bamboo structure is usually filled with thermal insulation cotton, so its thermal insulation performance is much better than traditional concrete, and the energy consumption of the house will be greatly reduced .

Bamboo. Copyright image from the gallery. Reproduction may lead to copyright disputes.

03

Conclusion

In 2021, energy consumption related to the construction industry exceeded 30% of global energy consumption, and carbon dioxide emissions reached 10 billion tons equivalent, accounting for 10% of total greenhouse gases.

In such an environment, the use of low-carbon, environmentally friendly, energy-saving and green building materials is crucial to the sustainable development of all mankind. With the advancement of science and technology, more intelligent building materials will also be used by humans. Our lives are inseparable from building materials, so let's start by choosing green and environmentally friendly building materials and jointly maintain our beautiful home!

References:

[1] Chenxi Sui, Jiankun Pu, Ting-Hsuan Chen, et al. Dynamic electrochromism for all-season radiative thermoregulation. Nat Sustain (2023). https://doi.org/10.1038/s41893-022-01023-2.

[2] Cai Qiting, Wu Yanting. Promoting the application of green building materials to build a new pattern of low-carbon development of industry-city integration[J]. Market Supervision and Management, 2022(18):1.

[3] Wu Zhenbing. Application of green building materials in construction engineering[J]. Engineering and Construction, 2022(003):036.

[4] Zhang Ting. Research on low-carbon building management system based on the concept of ecological city[J]. Urban Architecture, 2017(8):1.

Produced by: Science Popularization China

Author: Shi Wuyao Popular Science Creator

Producer: China Science Expo

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