With global warming and sea level rise, displacing millions of people in dry areas, there needs to be more cooling in buildings. Species extinction, widespread disease, uninhabitable heat, collapse of ecosystems, cities threatened by rising seas – these and other adverse effects on climate are accelerating and will accelerate in the coming decades, according to the UN World Advisory Council. which promises great analysis in 2022. New passive cooling for buildings.
The proliferation of air conditioners has problems with cost, materials, maintenance, housing and the generation of more heat than cold. Passive cooling means that it does not require electricity. It is widely used in the form of translucent multilayer polymers with sky views and convective chimneys in traditional African buildings. However, they have their limits. Two new passive options using readily available non-toxic substances – metamaterials and an unprecedented white that reflect maximum sunlight off the building – should be welcomed.
Beautiful, cool, 3D printed buildings
Cheap homes that are built quickly are needed by people everywhere, including the millions displaced by climate change and developing countries. One of the fastest and cheapest methods is 3D printing, as described in detail in the IDTechEx report “Rediscovered Concrete and Cement: Market growth, decarbonization 2022-2042”. They are usually ugly and if they still need painting, why not use a paint that will cool off?
The whitest color in the world
The whitest color in the world is made in an American laboratory. It is now in the Guinness Book of Records as the whitest ever made. Scientists claim that it is so white that it can reduce or even eliminate the need for air conditioning. However, IDTechEx analysts warn that it should be considered part of the toolkit because it is not customizable.
“When we started this project about seven years ago, we were thinking about saving energy and fighting climate change,” said Xulin Rouen, professor of mechanical engineering at Purdue University.
Make it totally reflective make it totally white. The color reflects 98.1% of solar radiation and emits infrared heat in the process. It absorbs less heat from the sun than it emits, so the surface cools below ambient temperature without consuming any energy.
A roof area of about 100 square feet can add 10 kilowatts of cooling capacity, more powerful than the air conditioners used by most homes, but locally. Ordinary white becomes warmer than colder. Colors on the market that are supposed to reflect heat only reflect 80 to 90% of the sun’s rays and cannot make a surface any cooler than its surroundings.
Two properties make this color so white: a very high concentration of a common, harmless chemical called barium sulfate — which is also used in photo paper and cosmetics — and the different particle sizes of barium sulfate in paint, Purdue scientists say. Purdue researchers have teamed up with a company to bring this ultra-white color to market.
Metamaterials are composite materials containing repeating patterns that are capable of manipulating electromagnetic and other emissions in ways that were previously impossible. For information on the upcoming commercialization of electromagnetic releases, see the IDTechEx report “Electromagnetic Markets for Metamaterials and Metasurfaces 2022-2042”.
Many of them are transparent, and one has been researched that can help with the problem of silicon and some other photovoltaic systems that need to be cooled to maintain efficiency. The combination of high fog, low visible light absorption and high heat emission make this nanocellulose metamaterial attractive for use as a solar cell coating, where its combined properties can increase the light absorption of the device, generate more electricity while increasing the lifetime and efficiency of passive radiation. cooling. Different colors are possible and buildings have better prospects for solar cladding and possibly passive cooling from windows covered with metamaterial.
In fact, passive radiative cooling removes heat from the surface and emits it as infrared radiation into space, where the atmosphere is transparent. However, the inequalities in energy density between solar radiation and the small flux of infrared radiation from surfaces near ambient temperatures require materials that emit heat energy strongly and barely absorb sunlight. The researchers randomly implanted resonant polar dielectric microspheres in a polymer matrix, resulting in a metamaterial that is completely transparent to the solar spectrum while also having an infrared emissivity greater than 0.93 through the atmospheric window.
The metamaterial consists of a transparent polymer encapsulating randomly distributed silicon dioxide SiO2 microspheres. Those interested in the upcoming $40 billion transparent electronics marketplace will find IDTechEx’s report “Transparent Electronics Materials, Applications, Markets 2021-2041”.
Coated with a silver coating, this metamaterial has a midday radiant cooling capacity of 93 watts per square meter when exposed to direct sunlight. In addition, the developers demonstrated high-performance and economical roll-to-roll production – essential for promoting radiation cooling as the energy technology of the future.