"Melting" Drywall Keeps Rooms Cool-could reduce the need for air-conditioning

[mod mom]

"Melting" Drywall Keeps Rooms Cool
Developers think these phase-change materials could reduce the need for air-conditioning.
By Katherine Bourzac
THURSDAY, FEBRUARY 04, 2010

Building materials that absorb heat during the day and release it at night, eliminating the need for air-conditioning in some climates, will soon be on the market in the United States. The North Carolina company National Gypsum is testing drywall sheets--the plaster panels that make up the walls in most new buildings--containing capsules that absorb heat to passively cool a building. The capsules, made by chemical giant BASF, can be incorporated into a range of construction materials and are already found in some products in Europe.



The "phase-change" materials inside the BASF capsules keep a room cool in much the same way that ice cubes chill a drink: by absorbing heat as they melt. Each polymer capsule contains paraffin waxes that melt at around room temperature, enabling them to keep the temperature of a room constant throughout the day. The waxes work best in climates that cool down at night, allowing the materials inside the capsules to solidify and release the heat they've stored during the day.

In some southern European climates, for example, the materials absorb enough heat during the day to save 20 percent of the electricity needed for air-conditioning. In northern Europe, where nighttime temperatures are cooler, a building incorporating the materials may not need an air conditioner at all, says Peter Schossig, an engineer at the Fraunhofer Institute in Munich, Germany, whose research group worked with BASF to develop the capsules.

The work is part of a push in the construction industry toward greener building materials that help maintain comfortable temperatures without using electricity. According to the U.S. Energy Information Administration, buildings consume more than 70 percent of the electricity generated in America, and about 8 percent of that is used for air-conditioning in homes and offices. Widely used lightweight construction materials including wooden framing and drywall enable contractors to put up buildings rapidly, but they don't store much heat, so temperatures inside fluctuate throughout the day.

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http://www.technologyreview.com/energy/24476/

[BrklynLiberal]

1. This sounds too good to be true. Hope it does not turn out that they are fatal

to all living things in some way....

[thereismore]

2. Paraffins should not be toxic, but who knows what else is there. Other than that, great idea. nt

[kestrel91316]

3. I don't want my walls absorbing any more heat than they already do, lol.

It would just make it harder to cool the place quickly when the sun goes down.

Product FAIL.

[ArcticFox]

7. look at it as if they're absorbing cold at night instead

and releasing that cold into your house during the day so that there is less cooling down that needs to happen after the sun goes down.

[kestrel91316]

9. For months at a stretch here we don't have anything resembling cold.

Just varying degrees of hot. And coolong off at night is much less than it used to be. So the heat just builds and builds in all thermal masses.

[Sebastian Doyle]

4. I wonder how these panels deal with the humidity

It's the humidity in my current residence that made me buy an A/C. I could care less how hot it is during the day. I just can't sleep at night in a fucking sauna.

[Kolesar]

5. Resins in some species of softwood do the same thing

Designers can use the wood as "thermal mass" in a passive-solar house to store heat from a sunny day to release it after hours.

[Gregorian]

6. We discussed this in energy courses 20 years ago.

It's pretty cool, no pun intended. The latent heat of the phase change absorbs heat, or emits heat depending upon the direction of the phase change. Man, I've lost almost everything I ever knew. So correct me if I'm wrong. But it's somewhat like a refrigeration cycle. Thermodynamics is pretty much the foundation of our modern society.

[eppur_se_muova]

8. Sounds like potentially flammable drywall.

Gypsum doesn't burn; paraffins do. Poor choice.

"The fourth little pig built his house out of wax ... and the Big Bad Wolf enjoyed BBQ."

[NNadir]

10. We could always perbrominate them, or at least perhalogenate them.

That worked out great in the refrigeration and electronics industry.

Or else we just fill all of our walls with gallium.

Just kidding.

I actually don't have too much of a problem with this approach. Many walls contain flammable wood, of course, but generally that's not a problem until the walls get very hot, in which case one is already in trouble.

It's actually quite hard to get many waxes to burn. Were it not so, candles wouldn't require a wick and would spontaneously ignite on some occassions.

I would imagine too, that there are a host of organosilicates or silicones that could achieve this task.