The weather is getting hotter and hotter. How to achieve cooling effect in future urban design?

Major cities are trying to solve this problem. Melbourne is drawing a "tree cover map" for city streets, and it is actively planting trees. Melbourne will increase the number of trees by 1 times by 2040. Milan will plant 3 million trees. Planting trees has many advantages: trees cover streets, and water evaporates from leaves, which can cool down neighboring blocks. Dallas, USA is pushing forward a new project, which maps the overheated areas in the city due to lack of trees, and then begins to plant trees in key areas where pedestrians walk. In 20 16, Madrid made a plan to plant all kinds of trees where it can be planted. Sometimes, trees are simply planted on roofs and exterior walls.

In new york City, in the past 10 years, roofs over 10 square feet were coated with white reflective coatings. Coating can reduce the temperature inside the building, make people more comfortable and reduce the use time of air conditioning; Just like cars, air conditioning is also a big source of heat emission, making cities hotter. Green roofs can also cool buildings and nearby neighborhoods. Sweet said: "From the perspective of the city, it is not helpful to build a roof garden just on top of the building. Only large-scale implementation can have a huge impact. " Tokyo has also taken action to lay cool sidewalks on the streets. In some cities, new sidewalks can be planted with grass and grow freely. Los Angeles has a three-pronged approach: building cool roofs, planting trees and building cool sidewalks. Peterson said: "We see a difference of 20 degrees Fahrenheit (6.6 degrees Celsius) between built and unfinished, which means that the conventional black sidewalk is 6.6 degrees higher than the road with cooling coating." Peterson also said that Los Angeles encourages manufacturers to develop new street coatings. At present, Peterson's organization is testing a variety of new coating materials.

If you want to cool the interior of the building, you can design a green and cool roof and exterior wall. In addition, there are other ways to reduce the use of air conditioners. When the sunlight hits the window directly, it can be blocked by the automatic window. The automatic window will open at night, at which time the sensor will automatically detect the temperature drop and command the window to close when the temperature rises.

In order to cool the building, material selection is also very important. Due to the thermal mass effect of concrete, the building can be cooled down in advance before the heat wave comes. Sweet said: "If everyone turns on the air conditioner at the same time, it will put pressure on the power grid and lead to power failure." Extreme weather can be predicted in advance, so thermal buildings can cool down and stay cool before the heat wave comes, so as not to bring down the power grid. When designing buildings, Arup will use special tools to predict the relationship between buildings and future climate.