- n° 290506
"France L'habitat aussi doit se préparer à affronter la canicule AFP [lundi 27 juin 2005 - 15h27] PARIS (AFP) - Penser à son habitat, le concevoir ou l'améliorer en fonction de la nouvelle donne climatique, devient une nécessité à laquelle le secteur du bâtiment se prépare grâce à de nouveaux matériaux intelligents et de nouvelles technologies. Le retour de la chaleur donne un avant-goût de ce à quoi il faut se préparer dans le futur, sachant que l'habitat n'est généralement pas adapté aux situations extrêmes, comme l'a démontré la canicule meurtrière de 2003, et que les solutions prennent du temps et de l'argent à être mises en oeuvre. Le point noir est l'isolation des murs qui se fait en France par l'intérieur et non par l'extérieur comme en Allemagne ou en Belgique. Cette isolation par doublage intérieur des murs est efficace l'hiver mais contreproductive l'été, indique un ingénieur du Centre scientifique et technique du bâtiment (CSTB), José Fontan. Une trop grande exposition au soleil, de grandes baies vitrées sans brise-soleil extérieur ont été autant de circonstances aggravantes pour les personnes âgées, premières victimes de la canicule de 2003 (15.000 morts), selon des enquêtes de l'Institut de veille sanitaire (InVS). Ces faiblesses des constructions modernes ou l'absence d'isolation sous les combles des immeubles anciens peuvent devenir dramatiques en cas de réchauffement de la planète. L'Agence de l'environnement et de la maîtrise de l'énergie (Ademe), un organisme public qui lutte notamment contre le réchauffement climatique, a lancé cette année un programme spécifique de recherche sur des matériaux plus performants et poursuit une mission d'information et de sensibilisation du public. ""Les professionnels du secteur (industriels, bureaux d'étude, architectes) ont pris en compte cette situation depuis l'an 2000"", a indiqué à l'AFP Pierre Hérant, chef du département Bâtiment et Urbanisme de l'Ademe. Un panel très large de solutions économes d'énergie est maintenant offert pour construire ou améliorer l'habitat que ""ce soit en vitrages, en produits d'isolation, en équipements thermiques ou climatiques"", explique cet ingénieur. Outre les matériaux intelligents (comme les ""smart glass"" qui protègent du soleil), les ingénieurs aident les architectes à concevoir des logements ou maisons en fonction de l'orientation du soleil grâce à des logiciels de calcul très sophistiqués, évitant ainsi ""naturellement"" la surchauffe des intérieurs. ""Un bâtiment bien conçu peut éviter les besoins de climatisation pendant l'été. Une maison de retraite vient d'être construite ainsi près de Toulon"", indique M. Hérant. Mais ces technologies ont un coût plus élevé de l'ordre de 10% à 20%, qui dissuade les maîtres d'ouvrage (promoteurs ou offices HLM) de les adopter. Les Français eux-mêmes, pas toujours conscients des enjeux écologiques, ne sont pas toujours prêts à payer les surcoûts d'une architecture et d'une technologie plus efficaces. Pour sensibiliser toutes les professions du bâtiment aux conséquences immédiates et à long terme sur l'environnement et la santé de l'acte de construire, la notion de ""Haute Qualité Environnementale"" (HQE) appliquée au bâtiment a été lancée par quelques précurseurs. C'est devenu depuis un label, en voie de certification, qui est le signe de ralliement de tous les intervenants du bâtiment s'engageant à fabriquer des bâtiments sains pour leurs habitants et l'environnement. _____ A visiter : http://www.hysafe.org/ Safety of Hydrogen as an Energy Carrier The EC funded Network of Excellence (NoE) HySafe*) contributes to the safe transition to a more sustainable development in Europe by facilitating the safe introduction of hydrogen technologies and applications. _____ Japon Fuel Cell Being Tested for World's First Application in Agriculture GS Yuasa Corp., a major Japanese manufacturer of batteries and power supply systems, has been conducting a field test of a new fuel cell in the greenhouse of a strawberry grower in Suzuka City, Mie Prefecture, since December 2004. The project, subsidized by the city and prefecture and scheduled to be completed in October 2005, is the world's first attempt to use fuel cells in agriculture. In the project, a direct methanol fuel cell that runs on methanol is installed inside a vinyl structure (about 990 square meters in floor space) owned by a local strawberry grower. The aim of the project is to develop a futuristic energy system for application in agriculture (in this case, to enhance the growth of strawberry plants). The total system is designed to use all the byproducts of electricity production: carbon dioxide emitted from the fuel cell unit (100 ppm/h) is used by the plants for photosynthesis; water from the unit is for plant growth; heat from the unit (2,000 kilocalories/day) is for space heating; and the electricity generated is for lighting and other uses in the greenhouse. During the trial, the strawberry plants grew well even in the middle of winter. Based on the test results, GS Yuasa will continue to improve the fuel cell system and develop new applications in agriculture, with the aim of commercialization in 2007. _______ France wins fusion project http://info.nature.com/cgi-bin24/DM/y/hTwN0BgUS80C30hpM0AW Decision over siting of ITER is made at long last. The ITER fusion reactor aims to heat a mass of gas plasma to 200 million °C. An 18-month deadlocked contest between Japan and Europe over who gets to play host to a US$5.5-billion experimental fusion reactor has finally come to an end. After much political back-and-forth, rumours and anticipation, the winner is France. On Tuesday 28 June, Japan bowed aside at a meeting of the six international partners in Moscow. Cadarache, in southern France, will be the site of the nuclear reactor known as ITER. In return, Japan was promised a host of benefits, including contract work, a significant leadership role, and support for hosting the next fusion project. Today's nuclear power comes from fission, a process by which heavy, radioactive elements such as uranium break apart and convert some of their mass into energy. But researchers anticipate that a much better source of energy would be the reverse process: fusion. This occurs when very light elements combine, such as hydrogen fusing to make helium. Unlike fission plants, a fusion reactor would not be vulnerable to meltdowns and its fuel could not be turned into nuclear bombs. Perhaps the biggest attraction of fusion is that the waste from a plant would only be radioactive for about a hundred years, rather than for hundreds of thousands of years. What you get out However, it takes intense conditions to fuse elements as they do in the centre of the Sun. Despite more than 50 years of research, scientists have not yet been able to make a fusion reactor here on Earth that produces more energy than they put in. But that's the goal of the long-planned ITER project. ITER aims to heat a mass of gas plasma to 200 million °C, and hold it in mid-air with powerful magnetic fields. This doughnut-shaped mass is expected to produce 400-700 megawatts of heat within the few minutes that it stays stable, which would be more than enough to power a town. If all goes to plan, ITER will generate five to ten times more energy than is put in to it. Once that principle is proven, researchers hope to take the next step and build a prototype fusion reactor called DEMO. This would convert the heat produced by fusion into useful electricity. Stalemate Russia, the United States, Europe and Japan agreed on the importance of building ITER in the late 1980s. But it has taken decades to convince all the parties involved that it was possible and affordable. For the past year and a half the argument has been over who would get to host it. The project carries much prestige, along with billions of dollars in construction, work for physicists and other contracts. After much negotiation, it has finally been decided that France will take the site. As part of this deal, the European Union will pay half of ITER's construction costs. The other partners will pay 10% each, mostly in the form of equipment and components. Japan will be given contracts to produce 20% of the project's components. Europe also agreed to support the nomination of a Japanese director-general for the organization that will be created to run the programme. And Japan will have a larger share of scientists working on the machine that it would be entitled to on the basis of its 10% contribution. Using a large chunk of European funding, Japan will host a facility to work towards the DEMO project, and Europe has promised to support any bid by Japan to host the reactor. The deal must still be ratified by member parliaments, a process that will probably take months. If all goes smoothly, construction should begin later this year. ""Frankly, ITER has got to go forward pretty quickly, or the negotiators will die of old age,"" says David Baldwin with General Atomics, a private company in San Diego, California, that has a government contract to do fusion research. Voir aussi (en français) : http://www.cea.fr/fr/actualites/articles.asp?id=653 http://www.irsn.fr/ http://www.liberation.fr/page.php?Article=307291 _______ Etats - Unis Hydrogen cars will save lives http://info.nature.com/cgi-bin24/DM/y/hTwN0BgUS80C30hou0AB Cleaner vehicles would be better for people, as well as the planet. Hydrogen-powered vehicles will save thousands of lives a year in the United States alone, researchers say. If all the nation's vehicles were powered by hydrogen fuel cells rather than fossil fuels, the drop in pollutants that cause asthma, respiratory problems and other potentially life-threatening conditions could reduce deaths by over 6,000 a year. So says a study in Science conducted by Mark Jacobson and colleagues at Stanford University, California1. ""That's a tremendous health benefit,"" says Jacobson. The work challenges a common objection to working towards a 'hydrogen economy', in which hydrogen replaces oil as the main fuel source. Many people argue that because hydrogen will probably be generated by burning fossil fuels, a hydrogen system is no better for our planet than oil. Both produce the greenhouse gas carbon dioxide, although at different points in the cycle of fuel production and use. There's a health benefit regardless of how the hydrogen is generated. Mark Jacobson Stanford University However, the problem with the internal combustion engine is not just its carbon dioxide emissions. It also produces poisonous carbon monoxide, smog-inducing nitrogen oxides, and ozone, an eye and respiratory irritant. Worst of all, it creates microscopic soot particles that cause a host of health risks and affect climate. Moreover, fossil-fuel vehicles tend to concentrate these pollutants in areas of high population density. Healthy approach Focusing on the health issues of hydrogen vehicles might convey their benefits to policy-makers in a better way than more general talk about emissions and pollution, says Ralph Cicerone, president-elect of the US National Academy of Sciences and an atmospheric chemist at the University of California, Irvine. ""It's an interesting angle,"" Cicerone says. Jacobson and his colleagues considered the effects of replacing all fossil-fuel vehicles in the United States with ones powered by hydrogen fuel cells, which burn hydrogen in air to produce electricity and water. Such vehicles exist already, although not in large numbers. The team then considered different ways in which the United States might obtain this hydrogen, including extraction from natural gas or coal, or electrolysis of water (which requires electricity, perhaps generated from fossil fuels). They ran computer simulations to determine the state of the atmosphere for each scenario. They also calculated what it would be like if all vehicles were converted to fossil-fuel/electric hybrids, of which there are various models on the market. Regardless of the hydrogen or electricity source, air quality improved in all cases. There was less carbon monoxide, ozone, nitrogen oxides and the eye irritant peroxyacetyl nitrate, as well as fewer sooty carbon particles. Fewer headaches This would bring substantial health benefits. The incidence of minor ailments such as headaches, sore throats and eye irritation drops by tens of millions a year in all the scenarios. The number of mortalities caused by air-quality problems falls by up to 6,400 a year with hydrogen cars. Hybrids would save fewer lives than that, but would be better for health than today's fossil-fuel burning cars. Unsurprisingly, Jacobson and colleagues find that the best-case scenario is that in which hydrogen is produced from water using electricity generated by wind turbines. The problem, however, is determining whether these scenarios are feasible. Producing hydrogen from water through wind power is expensive. And there are problems with storing, transporting and distributing hydrogen fuels. Still, Jacobson says he hopes that focusing on the health effects will help to make the case for hydrogen and renewable energy. ""It's not that nobody cares about these things,"" he says, ""it's just that nobody knows about them."" References 1 Jacobson M. Z., et al. Science, 308. 1901 - 1905 (2005). "
"France L'habitat aussi doit se préparer à affronter la canicule AFP [lundi 27 juin 2005 - 15h27] PARIS (AFP) - Penser à son habitat, le concevoir ou l'améliorer en fonction de la nouvelle donne climatique, devient une nécessité à laquelle le secteur du bâtiment se prépare grâce à de nouveaux matériaux intelligents et de nouvelles technologies. Le retour de la chaleur donne un avant-goût de ce à quoi il faut se préparer dans le futur, sachant ...
Architecture bioclimatique ; Bâtiment ; Canicule / Sécheresse ; Confort thermique ; Coût d'investissement ; Logement ; Haute Qualité Environnementale / HQE ; Matériau de construction
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