Telhados verdes podem dispensar o uso de ar condicionado

Recurso, cuja origem está no paisagismo, transforma capacidade natural das plantas em ferramenta de equilíbrio térmico

Instalado em 2000, telhado verde da prefeitura de Chicago é um dos mais famosos dos Estados Unidos. (Fotografia: Wikimedia Commons)

Horizonte desenhado por grandes edificações, solo forrado com concreto e escassez de áreas verdes – o cenário mais conhecido das metrópoles pode estar em vias de mudar com a popularização dos telhados verdes. O recurso inovador, originado de técnicas de paisagismo, transforma a capacidade natural das plantas de absorver gás carbônico e reter calor em ferramenta que trabalha para diminuir a temperatura do ambiente, além de contribuir para a diminuição da poluição do ar nos arredores da construção.

Estudos conduzidos pela EPA (Enviromental Protection Agency), órgão do governo americano para o meio ambiente, apontaram que a temperatura média no verão em um telhado verde pode ser registrada entre 33 e 48 graus, enquanto que, num telhado convencional, chega a atingir a marca de 76 graus.

A disseminação dos tetos verdes pode tornar o uso do ar condicionado obsoleto, pois a estrutura de vegetação que protege uma laje assume o papel de escudo contra o calor do verão tropical e reduz até 30% a temperatura dentro de uma casa, por exemplo. Durante o inverno, a estrutura funciona como isolante térmico ao impedir que o calor armazenado internamente seja liberado.

Mas antes de correr escada acima, é melhor ter em mente que construir um telhado verde envolve muito mais que o mero posicionamento de vasos num espaço vazio. De acordo com Paula Magaldi, paisagista paulistana e especialista na técnica, é preciso saber se o local é adequado para suportar o peso que será colocado por cima.

A impermeabilização é um ponto chave que, associado à maneira como será feita a drenagem e o escoamento da água, formam a lista de requisitos que uma edificação tem de preencher para receber os estratos e substratos de vegetação que vão formar a área verde.

Também não basta escolher as primeiras plantas da entrada do supermercado. Apesar de ainda vivermos num mundo onde a flora é vasta e variada, existem espécies que suportam mais incidência de luz que outras ou que precisam de mais manutenção.

O preço final da instalação e manutenção do teto verde, entretanto, depende de variáveis que vão desde o tamanho da área a ser coberta até o tipo de planta que será usada. Mas é possível estimar que os benefícios ecológicos que oferecem podem ser encarados também pelo viés financeiro. “O telhado verde é capaz de valorizar em até 20% o preço de um imóvel”, pontua a paisagista. Além disso, no médio prazo, será possível contar com uma conta de luz mensal mais amigável para o bolso.

Autor: Gabriela Ruic
Fonte: Exame
Original: http://bit.ly/snrVWr

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Paper towels least green way of drying hands, study finds

Warm air hand dryers and paper towels were found to generate 70% more carbon emissions than the newest technology

The Airblade, a high-speed hand dryer for public toilets from Dyson, was found to have the least environmental toll. (Photography: Sarah Lee / The Guardian)

Scientists at Massachusetts Institute of Technology have completed what is believed to be the first major study to assess the greenest way of drying your hands.

The research paper compared the seven most common drying methods in public toilets and concludes that paper towels and warm air hand dryers have the highest environmental toll – generating 70% more carbon emissions than the newest technology on the market, the cold air-driven hand dryer from UK manufacturer Dyson, which also commissioned the paper.

The study could also help conumers in comparing the environmental impact of products by distinguishing greenwash and making it easier to interpret the growing number of environmental claims. Last year Dyson and US paper towel corporation Kimberly Clark were involved in a row over research, which suggested “significant hygiene risks associated with jet air dryers and warm air dryers”, which Dyson dismissed as false claims.

MIT’s new research looked at the entire life cycle of various competing products from cradle to grave – materials, manufacturer, use and end of life – including use of transport, dispenser, waste bins and bin liners. Previous scientific studies into hand drying have tended to focus on the spread (and usually increase) of bacteria, amid growing concern about infection control and the impact of superbugs on public health.

Consumers typically perceive recycled paper towels to be better for the environment. But the report’s researchers found that the environmental impact of recycled towels equals that of virgin paper towels in a number of environmental measures, including CO2 emissions and and water consumption. In the US, 2% of total landfill consists of paper towels. Recycled and virgin towels were both found to generate over three times more carbon emissions than the Dyson Airblade hand dryers, creating waste, consuming more energy and also using more water.

By contrast, the environmental impact of warm air hand dryers occurs during use. Energy-heating elements and inefficient motors tip the sustainability scales, making warm air dryers up to 80% less energy-efficient than the Dyson Airblade hand dryer.

Sir James Dyson, the billionaire founder of Dyson and inventor of the bagless vaccuum cleaner, claimed the findings were an independent endorsement for his product, which is now available in 34 countries worldwide, with sales growing by nearly 70% last year. He commented: “Paper towels and warm hand dryers – like vacuum bags – are from a byegone era. Technology has moved on. People want to dry their hands quickly, competely and without damaging the environment .”

The Dyson Airblade was launched in the UK in October 2006, when it was heralded as more hygienic, more energy-efficient and more than twice as fast as any conventional electric hand dryer on the market. In the UK, it has gained a Carbon Trust rating, reflecting its green credentials.

MIT’s paper has been peer reviewed and the work will soon be submitted for publication in a leading academic journal.

Author: Rebecca Smithers
Source: The Guardian
Original: http://bit.ly/vldJRB

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Aston Martin prepara seu primeiro carro elétrico

(Fotografia: Divulgação)

A fabricante inglesa de carros esportivos de luxo Aston Martin – famosa pela ficção dos espião britânico James Bond – anunciou nesta semana o desenvolvimento do seu primeiro carro elétrico. O modelo mais ecológico da marca será uma adaptação do caçula urbano Cygnet, um Toyota iQ com a estética da Aston desenvolvido em parceria e lançado em 2009.

De dimensões compactas, o esportivo verde está previsto para chegar aos mercados em 2013, um ano depois do lançamento da versão elétrica da fabricante japonesa, e deve atender às cada vez mais rigorosas leis de emissões da Europa. A informação é do site inglês Car, segundo o qual o novo carro elétrico, apesar de ser o primeiro da categoria na história da Aston, não deverá inspirar estratégias futuras da marca. Isso porque, diz o site, durante a confirmação do novo carro, o presidente-executivo Ulrich Bez se mostrou cético quanto ao uso de propulsões alternativas aos sedãs e cupês de luxo da Aston. A empresa não liberou maiores detalhes sobre o carro.

Autor: Vanessa Barbosa
Fonte: Exame
Original: http://bit.ly/lWUnPj

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Recycling sewer water for drinking

Quiet conservationists

“YOU can’t create water, just like people can’t create gold or coal or oil. That’s nature’s business,” said John DeLaney, a pecan farmer in Comanche, Texas. “You might be able to conserve it.” But when I asked the logical follow-up question—whether he himself is a conservationist—Mr DeLaney demurred. “I don’t know what you mean by conservationist.” “Do you try to conserve water when you’re irrigating?” I asked. “Well certainly! Anybody with any sense does that,” he said, and explained that, if you had a three-month supply of food in your icebox and knew it had to last you three months, you would naturally ration your snacking.

One of the interesting aspects of researching Texas’s looming water issues—more on which in the coming print edition—is that on this issue some of the usual political divides are not so much bridged as simply moot. As Mr DeLaney says, anybody with any sense can see that the state is parched. Most of Texas has been blanketed in a severe drought all year. Crops are dying, cattle are being sold off, cracks have opened up in the ground, and one town has actually started recycling its sewer water for drinking. But even if it started pouring tomorrow, the issue is to some extent structural: the Texas Water Development Board (TWDB) projects that, because the state’s population is growing and its available supplies are dwindling, the state will need an additional 8.3m acre-feet of water by 2060—a nearly 30% increase in demand.

Under such conditions, there is little room for ignoring the issue, even if the cost of accessing more water will be considerable and even if the water experts have a tendency to talk about climate change more than is otherwise considered acceptable to some Texans. The TWDB’s draft water plan for 2012 puts the cost of recommended improvements at more than $53 billion, and is candid about the impacts of climate variability: “If temperatures rise and precipitation decreases, as projected by climate models, Texas would begin seeing droughts in the middle of the 21st century that are as bad or worse as those in the beginning or middle of the 20th century.”

Acceptance, of course, is not as good as action, and whether Texas will realise its goals with regard to water remains to be seen. The state doesn’t have $53 billion laying around. But perhaps the markets can be invoked to realise some gains. A statewide election today includes a couple of ballot initiatives designed to address the long-term water outlook; one of them, Proposition 8, would offer landowners a property tax break for implementing certain conservationist measures—an attempt to use incentives to override inertia.

And if the markets are not enough, then maybe some muscle can be used. Troy Fraser, a Republican state senator from Horseshoe Bay and chair of the Senate Committee on Natural Resources, says that he’s been telling oil and gas guys they need to clean up the water they use so it can be used again—fracking a gas well requires about a million gallons of freshwater a pop—and that if they won’t do it voluntarily, they could face some new legislation in the next session. He took a stern view of their complaints about the burdens of doing so: “It’s not a matter of not being cost-competitive. It’s just they wouldn’t make as much money.” Manufacturers, he allowed, have a more serious complaint; if water becomes more expensive in Texas, it might be cheaper for factories to move to soggier states. Still, Mr Fraser has a response for them. “The response is, there’s a finite amount of water available,” he says. Firm but fair, and an increasingly common view. Out west, as they say, whisky is for drinking and water is for fighting over. It may also be that water is worth fighting for.

Author: E.G. | AUSTIN
Source: The Economist
Original: http://econ.st/tPLLtl

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