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Hot water for Chile's slums, courtesy of the sun

A public housing project aims to improve the quality of life of Chile's poor, while also lowering emissions.

The basic unit has two stories, two bedrooms, and a floor space of just over 500 square feet. But it can be enlarged to three stories, up to four bedrooms and more than 750 square feet. Interior walls can be moved or removed, and floors added or subtracted.

Outer walls feature aerated concrete blocks with central cells, like cinder blocks, and millions of minute air bubbles in their walls for extra thermal insulation. The ceilings and bathroom walls are insulated with sheets of polystyrene foam covered by drywall.

To top off these cozy improvements, thermal-siphon solar water heaters crown the roofs.

The water heaters include a a flat solar collector and a holding tank for sanitary hot water, plus a kit to connect the water, pre-heated by the sun, to an auxiliary water heater. Fueled by conventional gas, the second heater can maintain or increase water temperature in the winter. The cost of each solar package with the auxiliary heater is $2,250.

The construction of an additional 297 houses nearby is planned to begin this year nearby. The per-house investment is close to $21,500.

For a family of four, using 10.5 gallons of water per day at a temperature of 115 degrees Fahrenheit, consumption of gas for heating water should drop by 62 percent. The new insulation standards should reduce energy demands for heat in winter by 45 percent and cooling demands in summer by 35 percent, said Minister of Energy Marcelo Tokman, while touring the site with then-President Michelle Bachelet.

Chile is a particularly poor country regarding fossil fuels. Almost three-quarters of its energy consumption during 2007 was based on fossil fuels: crude oil, natural gas and coal. The same year, the country had to import almost 100 percent of the crude oil and coal used, and most of its natural gas.

Petroleum products in Chile are as high as $4.35 per gallon of gasoline. Of course, with Chile’s minimum wage set at about $2 an hour, most laborers use public transport to get to work and, increasingly, bicycles to save on fare costs.

Solar water heaters are already popular in China, Israel and Spain. California recently approved rebates for switching from gas or electric water heaters to solar units, and beginning this year Hawaii will make solar water heaters mandatory on all new homes.

The first housing project in Chile with these energy savers will be christened "We Woman Can." Jacquelin Marin said she regrets that Bachelet won't be president when ribbons on her new neighborhood are cut, but she intends to invite Bachelet to the opening anyway. Maybe even to try her new hot shower.