Make the building an “air conditioner”. How did this “God Design” that keep you cool for the summer?

Shanghai issued its first high temperature yellow warning, and the maximum temperature will reach 35 degrees Celsius.

The highest temperature in Canada is approaching 50°C, and the death toll has surged.

The highest temperature in Antarctica broke the record again.

The world today is "hot". In addition to the noise and excitement of the Internet world, there are also hot waves in the real world. It is discussed that overheating is prone to extremes, and overheating is prone to heatstroke, and high temperatures may even cause dizziness and death in humans.

In order to cool down, cities and people also need to make some changes.

Portable air-conditioning and air-conditioned cities belong to only a small number of people

Every summer, people thank Willis Carrier.

As an inventor, he is not as famous as Edison, but the air conditioner he invented has made countless people feel stable and happy in the summer.

▲ Willis Carrier, inventor of the air conditioner

When you want to cool the city, air conditioning is also the first choice, but not all cities can afford it.

Dubai, the United Arab Emirates, wanted to build an air-conditioned city in 2014, so that city residents would stay “indoor” all year round because there are air-conditioning everywhere in the city.

▲ The air-conditioned city view of Dubai

The UAE’s plan is to build Dubai into the first temperature-controlled city, where tourists can come and experience a constant temperature life throughout the year.

At that time, the city of Dubai will be connected by a closed corridor of more than 6.5 kilometers, and different buildings will be connected to each other. Residents no longer need to feel the summer heat wave, because the city is basically covered by air-conditioning, and there are very few outdoor areas without air-conditioning.

In winter, the canopy of the promenade can be opened, and residents can continue to enjoy the fresh air. With suitable temperature and good facilities in the city, after setting a temperature-controlled city plan, Dubai is expected to receive 180 million tourists a year.

▲ All buildings are connected to each other, and air conditioning is everywhere

It's just that this plan doesn't sound very environmentally friendly. Coupled with multiple factors such as the drop in oil prices, the grand urban renewal plan has also been chopped off again and again. The number of development projects has been significantly reduced, the mega shopping mall has been divided into three, and the air conditioning system has to be re-evaluated. The Dubai holding company COO Morgan Parker in charge of this project told Bloomberg in 2016:

Installing air conditioners throughout the project is not only economically unfeasible, but also environmentally responsible.

The final solution is very traditional, that is, to make the buildings denser, to provide residents with more shaded sidewalks, and to increase the choice of paths through the building. All in all, the city-wide air-conditioning plan is completely unworkable.

▲ If the plan goes well, this is the future city of Dubai

If the urban air-conditioning plan is big, then the portable air-conditioning plan is very small.

Sony's portable air conditioner Reon Pocket has been out to the second generation. Its existence makes people walking on the street blow moist hot wind on their faces, while the portable air conditioner on the back is hidden in the suit to create a delightful air-conditioning. But the price of 1600 is not acceptable to everyone, and the Reon Pocket, which is placed on the cervical spine, is also a bit worrying about frozen shoulder.

Looking at more and more solutions, people have not found a cooling solution that can benefit more people in addition to energy saving, emission reduction and carbon emission reduction.

▲ Reon Pocket is like a portable air conditioner attached to the cervical spine

Recently, however, researchers from Purdue University have given a new solution-paint the city white.

Paint the city white and everything will be fine?

Applying a layer of light-colored paint to the surface of the building can reflect and block the radiation of the sun, thereby cooling the city. This is a commonly used method in urban architectural design. So most of the modern buildings we see are light-colored, not only for aesthetics, but also for practicality.

The principle of using light-colored paint to cool buildings is to reflect light, so the lighter the building paint, the better. What is more effective than white paint?

▲ The effect of white paint is the best

Researchers at Purdue University previously introduced the whitest paint in the world, made of calcium carbonate, with an albedo of 95%. Recently, a further upgraded white paint was relaunched. It is made of high-concentration barium sulfate, not only the color is whiter, but also the reflection effect is better.

The two coatings that continue to refresh the "whitest" record are all improved on the basis of an inorganic substance such as titanium dioxide. As a common raw material in commercial white coatings, titanium dioxide has a good UV shielding effect and is a "sunscreen" for textile fibers and cosmetics.

▲Do you want pure white buildings? Picture from: Simon_M

In the case of white paint made of titanium dioxide with an albedo of 90%-92%, the latest white paint has analbedo of around 98% , which has made considerable progress in terms of the functionality of the paint. The higher the albedo of the coating, the more beneficial it is for building temperature control.

In addition to the high albedo, this new type of coating can better reflect solar radiation back to space at a specific infrared wavelength of 0.008-0.013 mm, instead of staying in the earth’s atmosphere and aggravating global warming.

The paper shows that when the sun shines on this particular white paint, nearly 10% of the radiation will be reflected by these wavelengths.

▲ The author discusses that the new coating has a higher cooling efficiency

In the actual test, the room temperature of the building using this kind of coating is 4.5℃ lower than the outdoor temperature, which is currently one of the best urban cooling solutions. In addition, the difficulty of "painting white" buildings is not high, and the process of coating work does not require electricity, and it will not cause more harm to the environment. Builders can completely apply this kind of coating.

It can be said that this kind of paint is like a non-resource-consuming "building air conditioner", or the kind that can be used continuously.

Imperfect solution, continuous high temperature struggle

Although the use process does not consume resources, the paint is still not perfect in the production process.

Two-thirds of the raw materials of this coating are derived from ore, which means that to be widely used, mining is required-one of the human behaviors that has a greater impact on the environment. In other words, the paint you paint for the sake of environmental protection will cause a certain amount of environmental pollution . This kind of solution that is difficult to achieve both ends is what we must face in today's environmental protection work.

▲ White building. Picture from: Simon_M

It is not practical to use this kind of paint in all buildings. Apart from economic cost considerations, the exterior design of buildings is also a problem. No one wants to walk out the door to see a vast expanse of whiteness. Although this is not a snowy field, it may not cause snow blindness, but light reflection can also cause new problems. In the process of use, the aging of the coating and the decline of work efficiency are also factors that need to be considered.

This kind of brainstorming attempts to cool down urban buildings are actually not many. Applying light-colored paint to buildings is one of them. Although it is not as effective as the new white paint, it is also helpful. Planting various green plants on the outer wall of the roof can also help the building absorb heat and block sunlight, but such a design may also have a certain impact on the service life of the building.

▲ There is also a greening rate outside the building

The new cooling plan is not limited to buildings. Some people also want to renovate the urban road surface to make "the road up to the sky, cooling down the heat."

The old way is to paint white, but to paint the road white, you have to consider the safety of the road surface and the durability of the paint. Charleston County, South Carolina, USA, tried this method. They made the road maintenance agent white to reduce the ground temperature by reflecting more light, but this maintenance agent will also reduce the road's anti-skid to a certain extent. Performance has an impact on driving safety.

▲ Whitening the ground may also be an effective way to cool down

For a long time, many scholars want to use synthetic mineral materials to make urban roads have a more efficient cooling mechanism, and even imagine a solution that can store rainwater under the road and help reduce the temperature of the road surface. But these solutions also have their own problems. Either the cost is too high to replace low-cost solutions, or there are many side effects.

From air-conditioning to paint, there is no one-hundred-percent perfect solution for cooling the city. It is best not to harm the environment too much when the program is cooling down, and there will be no more pollution, which makes everything more difficult.

It's just that between the full score and the zero score solution, the most terrifying thing is to do nothing.

Not too interesting, not too optimistic.

#Welcome to follow Aifaner's official WeChat account: Aifaner (WeChat ID: ifanr), more exciting content will be provided to you as soon as possible.

Ai Faner | Original link · View comments · Sina Weibo