Buenos Aires promotes "roof gardens" to save energy

Buenos Aires, Agency
Authorities in the Argentine capital are using tax breaks to encourage people to establish gardens on the terraces and roofs of buildings with the goal of improving the urban environment and saving energy, as is already being done in Tokyo in Berlin, among other cities.

The "green roofs" provide numerous environmental benefits in the cities where they have been set up, including improving the air quality and reducing the average urban temperature, architect Jorge Leder, who is in charge of building the first of the gardens in Buenos Aires, told Efe on Monday.

Buenos Aires, a city of 200 sq. kilometers (77 sq. miles) and 3 million residents, has about 2 sq. meters (21 sq. feet) of green space per inhabitant, much below the 10 sq. meters (106 sq. feet) per person minimum set by the World Health Organization.

Seeking to "set an example," the first of the gardens will be established on the municipal Management and Participation Community Center No. 2, whose roof over the next two months will be transformed into a green space with bins and pots filled with Sedum plants occupying some 30 sq. meters (318 sq. feet).

"The most difficult thing was to find the proper plant, because it had to withstand all types of weather and require very little watering," said Leder, who collaborated on the project along with Lilia Vence, a researcher with the Agronomy Department at the University of Buenos Aires.

Apart from the benefits the roof or terrace gardens will provide to the city, they will also offer many advantages for the buildings where they are located, he said.

For example, the plants on the roof of the community center will retain rainwater and ameliorate the temperature, making it less cold or hot in the offices located in the building below and thus allowing those offices to consume less energy to provide a comfortable environment for workers, Leder said.

The gardens will also have a solar collector that will heat the water in the pipes of the building and also a channeling system that will collect the dripping water from the air conditioning units to reuse it in irrigating the plants and cleaning the patios, said Facundo Carrillo, the center's director.

The new garden facilities will also allow authorities to increase the useful life of the impermeable metal sheets on the terraces because the plants and the solar panels "will intercept the UV (ultraviolet) rays that had aged and degraded them," Vence said.

The construction of the community center garden was completed several months ago after the study performed by the Leder-Denegri architectural firm won the competition held by the Buenos Aires Environmental Protection Agency, or APRA.

The project - which so far has cost 40,000 pesos (about $10,000), half of which was financed by APRA - was begun in 2008 at the Agronomy Department, where researchers investigated which plants would be "appropriate" for the type of weather conditions and sun exposure on roofs in the capital, Leder said.

"The conquest of the urban desert" will allow commercial buildings, single-family homes and multi-family apartment buildings that build such roof gardens to pay lower municipal taxes, and they will continue to be installed "by way of example" on most municipal government buildings.

Tokyo, Berlin, Sao Paulo, Mexico City, Chicago, Toronto and Moscow are among the cities that also have "ecological roofs" on some of their buildings to help combat the "heat island" created by the buildings and to cooperate in the struggle against climate change.