Three New Materials that will Change Building Envelopes

Sunday, January 24, 2010

This time we’re presenting three materials that are going to have a big impact on the design of envelopes for sustainable buildings. The first is a Green Cement that is made as a precipitate of processed CO2. Another is Nansulate®, a coating that has excellent thermal resistance properties and also provides mold protection. The third is EcoRock, a new sheetrock, 80 per cent of which is recycled material, that requires no heat to produce it.

power plant 1. Green Cement, a new, environmentally friendly cement that would use and sequester CO2 instead of producing it is, literally, in the hopper. The Portland cement we all know is the third largest source of greenhouse gas pollution in the U.S., according to the U.S. Environmental Protection Agency. One ton of cement produces about a ton of CO2. The US produced 94 million metric tons of cement in 2008, and the rest of the word produced a lot more than that. If coal is ever to come clean as a source of electricity, a reasonably cheap method for sequestering the CO2 emitted while it burns is a ticket to a much greener future. Using the CO2 to produce something useful instead of burying it in the ground would create an environmental home run.

Now a company called Calera, Inc., proposes to do just that. Locating production directly at power plants, Calera passes the flue gases through briny water and then dries the slurry that results with spray dryers that utilize the waste heat of the flue gas. Brent Constanz, founder of Calera, quoted in Scientific American (August 2008), said, “We are turning CO2 into carbonic acid and then making carbonate. All we need is water and pollution.” (Carbonic acid, H2CO3, is H2O and CO2, combined.)  The product is a chalk-white cement that can be mixed – just like Portland cement— with rock material to make concrete.

Currently, Calera is trying out its process at the Dynergy Corporation’s Moss Landing power plant on the Pacific coast. There, it’s taking a part of the flue output from one of the plant’s smokestacks and putting it through seawater to produce a new cement.  But sea water is not a de facto requirement. Inland, it might be able to use the water that is a waste byproduct of oil and gas drilling by hydrofracturing, water that is totally or virtually unreclaimable in part because of its high salt content.

Constanz expect that Calera’s cement will also have a big cost advantage over Portland producers. “Our costs of goods are lower than Portland cement because we don’t have to burn coal or build a quarry and quarry limestone,” he explains, “so our capital costs are quite a bit lower.” The combination of lower cost and the ability to not only sequester CO2 but to lock it up in a useful product with waste heat is almost too good to be true, but it looks like the future. We’ll know later this year, when Calera’s prototype system is operative. After that will come the difficult job of convincing the old dog of the whole construction industry to learn and accept new tricks.

nansulate 2. Nansulate® is a coating that, like paint, can be sprayed, brushed or rolled onto a surface, but which also has significant insulating properties. This product was around for several years as an industrial coating, used to insulate industrial boilers and other industrial equipment. Industrial Nanotech, which produces Nansulate, only recently decided that it would make it available as a building material after it found that its staff was using it – successfully – in their homes.  It was then that the company realized that could be used to reduce heat transfer in commercial and residential buildings.

Nansulate is produced as a nanocomposite coating with an extremely low thermal conductivity that inhibits heat transfer in a thin layer. To achieve effective thermal insulation normally requires the application of three coats to achieve an average thickness of 7 mm. At $80 per gallon for 450 sq ft (or 150 sq ft triple-coated), while pricey when compared to using conventional insulation for new construction, it becomes downright cheap when considering the cost and labor involved in adding insulation to existing structures. It is applied exactly like paint, with a brush or roller, and comes in clear or white.

Since the nanoparticles used in the coatings are water-repellent, they also have anti-corrosive properties when applied to metal surfaces and are extremely mold-resistant, as documented in several independent laboratory tests where identical surfaces were compared, some painted with Nansulate, some with conventional paint, and exposed to moisture. The other surfaces developed large areas of mold; the Nansulate surfaces had virtually no mold at all.

The company offers a list of commercial and industrial building customers around the world, including airports, museums and other major commercial structures. Because the Federal Trade Commission forbids coatings from declaring an R value, Nansulate can only provide results from case studies. In a residential case study, the reduction in energy use in kilowatt hours was 42 per cent, compared with the energy use over three years before the Nansulate application.

The company states it can also contribute to LEED points both in terms of insulation and low VOC content. With a product acceptable for LEED certification, architects and engineers who have to deal with building envelope problems that might be solved by thin-film insulation should give this product a closer look.

3. EcoRock is a new form of sheetrock made almost entirely from recyclable materials and requires no heat to form the material or the sheets, which solidify in a chemical reaction. Kiln dust, fillers, slag, fly ash and other industrial castoffs constitute 80% of its contents; the rest are proprietary, but Serious Materials, the company that makes it, declares that none of them are toxic or volatile.

Conventional sheetrock is made from gypsum, which must be heated to 500o F in special kilns before it is mixed with water and starch and formed into sheets papered on both sides, and is heated again to dry and harden. Including the process of mining gypsum, its principal material, the production of conventional dry wall produces massive amounts of greenhouse gases, an estimated 20 billion tons a year. Serious Materials’ CEO, Kevin Surace, said, “We want to change that. We wanted to reduce that by 80 per cent, and EcoRock achieves that. This will have a huge impact.”

Because it contains starch and paper, and absorbs water, conventional drywall is also subject to mold and is attractive to termites. To counter this problem, the industry is producing drywall with additives to make the material mold- and bacteria-resistant.  As a sustainable bonus, EcoRock is extremely water-resistant and does not require any treatment to be mold- or water-resistant. It scored a 10 (out of 10) ASTME rating, when test showed it had zero mold growth under appropriately wet conditions over a six-week period. The 5/8th-in sheets are fire-rated at 1 hr, per ASTME E119. The half-inch sheets are not fire-rated.

Serious Materials is starting to produce EcoRock at plants in Boulder, Colorado, and Syracuse, New York. Currently, the price for a 4-by-8-ft, 5/8th-in sheet is expected to be about $17, but Surace says the company expects this to come down as production ramps up. The company states that the use of EcoRock can contribute LEED points for “recycled content, regional materials, low-emitting materials, and innovation in design.”

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One Response to “Three New Materials that will Change Building Envelopes”

  1. Abbey Taylor

    This is a very useful information for my husband who is going to re-paint our home this weekend. In doing so, he bought gallons of insulating and heat reflective paints from add4green because he is convinced that using such paints to re-paint our home’s roof, interiors and exteriors will help us save energy and reduce our heating and cooling cost. As a housewife who deals with budgeting my husband’s monthly income, I think any kind of saving is worth the trouble.


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