International. The global air conditioning market has been growing strongly since the 2000s. Air conditioning sales increased fivefold between 2000 and 2017 in China, for example. A JARN study published earlier this year indicates that growth is expected to continue, with a forecast to increase by 3% in 2019.
The increase in the number of devices has a double impact:
Significant energy consumption (9% of New York City's annual consumption in 2017).
An increase in greenhouse gas emissions.
Current research is moving in two directions: the development of energy-efficient appliances, or the study of alternatives to generate freshness without using any device. Therefore, evaporative cooling techniques are studied, especially in cities, to avoid heat islands.
An innovative bitumen has been tested for three years on some streets in Paris, France. It is lighter than traditional coatings, which increases the effect of the albedo: it better reflects the sun's rays and therefore absorbs less heat. In addition, this coating has good water retention capabilities. When watering it (with non-potable water), the actual temperature drop was estimated at 2 ° C and the decrease in the perceived temperature at 3 ° C.
A study examining the role of trees in urban climate regulation is currently underway in the UK. It is funded by the Department of Environment, Food and Rural Affairs. It has already shown that areas with a large number of trees can be 4°C colder than areas without vegetation.
The most efficient trees for freshness have a large leaf area, dense crowns and high transpiration rates. Plant transpiration is the process caused by the evaporation of water from leaves that cools the ambient air. Bananas, sessile oaks and cherry trees are species specially adapted for the city of London.
By choosing these trees and planting them near office buildings, £22 million could be saved each year. Energy consumption could fall by 13% in London thanks to the phenomenon of evapotranspiration.
Source: IIR.
