‘A perfect symbiosis’: planting vines and other ways hot cities are creating cool spaces
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Version 1 of 2. Living – or crocheted – canopies and a 3,000-year-old Persian technique are among methods being used to cope as temperatures soar As Spain takes a breath after yet another brutal summer heatwave, with temperatures above 40C in many parts of the country, the residents of the sherry-making town of Jerez de la Frontera have come up with a novel way to keep the streets cool. Green canopies of grapevines festoon the town, reducing street-level temperatures by as much as 8C. “We’re planting vines in the old city because we hope that in two or three years we’ll be able to brag that this has put an end to stifling temperatures,” said Jesús Rodríguez, president of Los Emparrados, a group of residents who aim to beautify and green the city’s streets. For decades the local sherry producers have kept their wineries cool with emparrados (vine arbours) but now the practice has been extended to a cluster of streets in the old town. Not only are vines part of the essence of Jerez, they also have several advantages over trees. They need to be watered only in the first two years and they are deciduous, letting in the winter sun between November and March. Within three years of planting they will form a complete canopy over a narrow street. Just a single vine stem growing up the side of a house can offer a lot of shade. In the sherry houses, where this has been the practice for more than 60 years, the leaves from a single vine form a canopy of 60 sq metres. The variety chosen is Vitis riparia, cultivated to produce few grapes, avoiding streets made sticky by fallen fruit. “There’s a perfect symbiosis in that by planting vines in the street we’re doing something for the city as well as celebrating the vines of Jerez. Our philosophy is closely linked to Jerez vines,” said Begoña García González-Gordon, of Los Emparrados. Now the local authority plans to extend the canopy from the four streets in the pilot scheme to 20, linking the 14 parks and green spaces in the old city over an area of 1.5 sq miles (4 sq km). In the Andalusian town of Alhaurín de la Torre, 125 miles east of Jerez, the streets are shaded under a canopy of colourful crocheted blankets. This is another community initiative, the work of Eva Pacheco, a local crochet teacher, and her students, and provides shade over an area of 500 sq metres. La Calle de las Mandalas is a similar crochet project in the Andalusian town of La Línea de la Concepción, but instead of squares the canopy consists of 860 round mandalas joined together. The mandalas are the work of the La Línea Association of Crocheters. In many Spanish streets and squares, shade is provided by sheets of canvas stretched between poles of buildings. In Calle Santa María in Valladolid, in north-west Spain, residents have taken this a step further, creating a series of awnings planted with gypsophila and other plants that are slung on cables between buildings, providing shade and hanging gardens. Cities around the world are finding novel ways to confront the problem of rising temperatures. Paris has created an app pointing to an interlinked network of 800 “cool islands”, from parks and forests to swimming pools and museums. The islands are for the most part linked by cool walkways, and the idea is that no one is more than seven minutes from a cool oasis. The Colombian city of Medellín has succeeded in bringing temperatures down by two degrees through a series of 30 green corridors consisting of vertical gardens, plants and about 1m trees. The scheme also improves air quality and is starting to attract wildlife back to the city. Sign up to Down to Earth The planet's most important stories. Get all the week's environment news - the good, the bad and the essential after newsletter promotion However, shade is not the only way of cooling the city. The Andalusian capital, Seville, a region that is bearing the brunt of climate breakdown, has revived an ancient Persian technique, the qanat, as a form of outdoor air conditioning. The 3,000-year-old technique, used throughout the Middle East, traditionally consists of diverting cool mountain water through underground channels, which are perforated at intervals to cool the surrounding air. The Cartuja qanat project in Seville is based at an abandoned amphitheatre on the island of Cartuja in the Guadalquivir River, the site of Expo ’92, much of which has fallen into disuse. Partially funded by the EU, the €5m (£4.3m) project uses solar energy to drive water through deep underground channels. Underground, air captured at 40C cools to around 17C. Vertical vents along the canal drive the cool air around the water upwards, reducing the ground temperature. At night, some water is pumped up on to the roof where it cascades down solar panels, cooling in the night air, before returning underground. During the day, solar-powered pumps push the cooled water above ground, where it is funnelled through small pipes on to fans that spray the cool air into the ground floor of the amphitheatre, while a separate set of nozzles spray water mist into the air. Further cooling is provided by shade trees and by painting the roof of the auditorium white to reflect sunlight. These elements have combined to reduce air temperature in the area by 6-7C and there are plans to replicate the qanat scheme in other parts of the city. |