- $100 DIY Shelter Could Help Homeless Haitians
- New Close-Ups of Saturn’s Moons Mimas and Calypso
- Fog Decline Threatens California’s Towering Redwoods
Posted: 15 Feb 2010 09:00 PM PST
With just $100 worth of plywood and screws, almost anyone can build a shelter known as a Hexayurt that can last three years and possibly even withstand a hurricane. The simple DIY structure could be a critical temporary solution for some of the estimated 1 million or more people left homeless in quake-torn Haiti.
Aid agencies have distributed around 10,000 tents to Haiti so far, according to to the International Organization for Migration (IOM), one of the dozens of charity groups in Haiti focused on emergency shelter. But 200,000 are needed, and even then, the tents won't stand up to the weather.
"Tents are a three to five month option in the midst of the dry season," said Vincent Houver, IOM Chief of Mission in Haiti, in a recent press release. "But emergency and transitional shelter solutions sufficiently durable to last at least two years need to be found before the heavy rains arrive in a few months."
Tents do have the benefit of a supply chain already in place that makes it easy to ramp up production when disaster strikes, and they can be transported to remote sites and set up relatively quickly. But they run around $300 to $400 and only last about a year, in good weather.
"Once those tents are shredded, people are homeless again," said Vinay Gupta, a self-taught risk management consultant and inventor of the Hexayurt.
In addition to being longer lived, the Hexayurt is both easy to assemble and cheap. I built my own for Burning Man in 2008 from fire-safe insulation board and industrial tape. It took a couple of hours to make the pieces at home and an hour or two with some friends to assemble it on site. My cozy abode withstood fierce dust storms that lasted for hours and maintained a comfortable temperature that allowed me to sleep until noon, long after the blazing sun had driven my campmates from their tents.
At 70 square feet, my six-foot "stretch" Hexayurt was big enough for one and required only seven sheets of insulation board. A Haitian family of five would need a bigger structure made of plywood. Eighteen sheets will build a 276 square foot structure with four foot tall exterior walls or a 166 square foot structure with eight foot exterior walls.
"I have no doubt whatsoever that this concept could work in Haiti," said Linton Wells of National Defense University in Washington, DC, founder of Transformative Innovation for Development and Emergency Support.
Wells field-tested Hexayurts made of foil-backed insulation board in the mountains of West Virginia. They survived 60 to 70 mile-per-hour winds, and only gave away when they were attacked by bears.
Materials for an entire Hexayurt village can be delivered on one flatbed truck. The hexagonal design makes it easy to add rooms by "honeycombing" more Hexayurts to the original structure. Families can build their own home or use local labor, which has the added benefit of developing skills needed to maintain the local economy.
And at five dollars per plywood sheet, $100 will cover the cost of the basic building materials. Painted, a plywood Hexayurt should last up to three years, and Gupta says it's sturdy enough to survive the Haitian rainy season, and much worse. Science for Humanity is organizing structural analysis to see how the Hexayurt will respond to the hurricane conditions arriving soon in Haiti.
Plywood is plentiful and used worldwide, so supply chain issues are minimal. "And you can never have enough plywood in a disaster. You can use it fix damn near anything," Gupta said. Atlanta-based Courageous Church is currently shipping plywood to Haiti and mobilizing 50-100 volunteers to build Hexayurts on site during spring break.
Emergency shelters must be able to adapt to the local conditions on site, said Bruce LeBel, executive director of World Shelters, a non-profit organization that designs, builds and delivers emergency structures.
World Shelters has designed different types of structures including The Buckminster Fuller-inspired U-Dome and the frameless, hard-shell TranShel, but these are meant to be longer-term transitional structures that cost $2,000 and last 10 years.
What's needed in Haiti are flexible designs that can be built on site with local labor, not ready-made structures, LeBel said. "It's really important that emergency shelters adapt to the context."
Right now, he says aid agencies in Haiti are looking for ways to use 200,000 sheets of lightweight plastic that were scheduled to arrive this week. Currently, Haitians are using the sheets any way they can, sometimes attaching them to the sides of wrecked buildings or other structures. World Shelters has offered their design called JAS (Just Add Sticks) which is a framing system for the plastic that uses materials such as bamboo as corner connectors.
The need for temporary housing following a disaster has inspired many other designs as well. One already in use in Haiti is ShelterBox, invented by Rotary International, a worldwide service club organization. The sturdy plastic boxes are packed with a tent, basic tools, and survival equipment specific to local conditions such as water purifiers, and insulated ground sheets.
On average, a ShelterBox costs $780, including packaging, delivery and distribution. But they still use tents, with numerous small parts that can break or become lost. Nonetheless, seven thousand have so far been deployed in Haiti. The photo taken Feb. 2 shows a camp with 400 ShelterBox tents that house thousands of Haitians.
The crazy-looking reCover Shelter was designed for a class project by four Syracuse University students. Like a giant accordian, the structure is collapsible and customizable. It consists of 12 4-by-8-foot sheets of pre-cut and pre-folded polypropylene that simply need to be joined at the corners with zip ties and tethered to the ground on site. It's larger than a relief tent and can be set up in minutes.
Designer Matt Malone estimated the shelters would last a few weeks and could be recycled into new sheets of polypropylene after use. So far, Malone and his co-designers have built one full-scale prototype, which cost less than $200 at retail prices. To mass-produce the customized sheets would require adding two simple steps to the manufacturing process, he said.
In order to move beyond tent cities, Haiti will need transitional housing that is sturdy and scalable. It should utilize local resources whenever possible, and it must be cheap. Otherwise, said Gupta, "There is not enough money on the table to take care of Haiti. We're sticking a band-aid on a gunshot wound."
Images: 1) Hexayurt/Vinay Gupta. 2) Hexayurt at 2008 Burning Man/Renee Davidson. 3) World Shelters JAS design/Kurt Therkelsen. 4) ShelterBox camp in Haiti/ShelterBox. 5) reCover Shelter/Matt Malone.
Posted: 15 Feb 2010 04:37 PM PST
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NASA's Cassini spacecraft took a swing by Saturn's moons Mimas and Calypso over the weekend and sent back some fantastic shots released today.
Mimas is the 20th in size of Saturn's 62 moons with a diameter of about 246 miles, and it may be the smallest body in the solar system that has been rounded by gravitational forces. It isn't completely round, however, as can be seen in the image above, taken from around 15,000 miles away. Tidal forces have made its longest axis 10 percent greater than its shortest.
Calypso, seen in the second image of this gallery, is a tiny, odd-shaped moon that was only discovered 30 years ago. It has one of the most reflective surfaces in the solar system, having been sandblasted by particles in Saturn's E-ring, emitted by the plumes of the moon Enceladus.
Image: NASA/JPL/CICLOPS/Josh Riley
Posted: 12 Feb 2010 10:00 AM PST
The California coast has seen fewer foggy days in the last century, threatening the health of the region's majestic redwood trees.
Over the last century,new research suggests the average daily fog has decreased more thanthree hours, causing the coast redwoods to lose more water in the dry summer season, leaving them more susceptible to drought.
"Redwoods are an iconic species and we all love them, but I think it's important to note that lots and lots of species depend on fog," said climate scientist Phil Duffy of Climate Central in Palo Alto, California, who was not involved in the study. "So if you really do increase or decrease the fog, then that will have effects on whole entire ecosystems in these coastal hills."
The habitat of the Sequoia sempervirens is confined to a misty, 30 mile-wide strip along the California coast, stretching from Big Sur in Central California to just north of the Oregon border. The giant trees can reach 380 feet tall and livemore than 2,000years.
Fog isone reason the trees are able to grow so tall. They have developed the ability to absorb as much as 40 percent of their water directly from the fog. Without this adaptation, the trees would not be able to move water from their roots all the way to their tops.
Fog often rolls ashore along the California coast from June through September.The hot, dry inland air rises and creates a vacuum that sucks in the cold, vaporous air from over the ocean, said biologist Todd Dawson of the University of California, Berkeley, co-author of the study Monday Proceedings of the National Academy of Sciences. The fog keeps the colossal trees cool and moist, even when the areas just 50 miles inland are hot and dry.
The behavior of fog has been difficult tocapture with computer climate models, but arecent modeling study suggested global warming would lead to a foggier coastline. So Dawson's team wanted to see what the historical record actually showed.
To determine how summer fog had changed over time, the team analyzed hourly sightings of fog that were recorded from 1951 to 2008 at one airport in Arcata, near the northern edge of the trees' range, and one in Monterey, near the southern end. Any low hanging cloud cover at or below 1,300 feet was considered fog.
Overthe past 58 years, the coastal fog hasdecreased byabout 1.3 hours a day, said climate scientist James Johnstone of the University of Washington, lead author of the study.
They also mined temperature, humidity, and wind data from across California, Oregon, and Washington from the same period to see if there there were any trends between coastal fog and inland weather. They found the difference between the coastal temperature and the temperature about 50 miles inland was key. The temperature differential creates a vacuum that "pulls the fog on land, so the greater the difference between inland and coastal, the more power it has in drawing the fog on shore," Dawson said.
Using that relationship, they went back and looked at temperature information dating back to the early 1900s and extrapolated fog conditions over that period.
The temperature difference between inland and coast went down, mainly because the coast was heating up even faster than inland.That reduced the force to pull fog ashore. Warmer sea water has also caused less fog to form in the first place, Dawson said. As a result of these factors, the fog decreased by about 3.5 hours a day over the last century from 13.5 hours to about 10 hours
Next, the team examined how warmer, drier days affect the tallest trees in the world, the coast redwoods. They analyzed months of data on water exchange and water flow in the trunk of one redwood tree from the Grove of the Old Trees, a preserve in Occidental, CA.
On foggy days, the leaves lost less water to the air. Sap flow, another measure of water use, also dropped. The fog helped the trees lock in moisture during the drier summer months.
The sunnier, clearer summers will make the trees more vulnerable to drought. In other experiments where redwoods experience water shortages, "We see die back at the very tops of the biggest trees," Dawson said. "At the other end of the spectrum, you can also imagine that if the soil gets dryer and dryer because there's less and less fog, then the newest trees — the little seedlings that are germinating — they may not survive through the dry summer months."
The teamcan't say for sure whether human-caused climate change is a culprit in the disappearing fog, but "it seems likely that it may be the case," Dawson said. To link the drier coastal air to global climate change, the group would have to do an "analysis of fog everywhere around the world, and how it's changed everywhere around the world, to say okay, there's this general global pattern."
Some emerging evidence does suggest the vanishing fog may be more than a California phenomenon. Early studies show some of the formerly foggy coasts off of Chile and South Africa have become less so in recent years, Dawson said.
Citation: "Climatic context and ecological implications of summer fog decline in the coast redwood region," James A. Johnstone, and Todd E. Dawson. 2010 PNAS.
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