I heard of this at a green building conference today. First time I’d ever heard of it, and it’s apparently not available in the U.S. yet. Supposedly it will be soon- they’re already using it in Europe.
What I heard today- 1/2″ of phase change wallboard, used just like normal drywall, provides the thermal characteristics of 3 1/2″ of concrete wall. When the wax melts, at around 73º F, the phase change absorbs heat energy, to slow down the rise in ambient temperature. When the wax solidifies, at the same temperature going down, it gives off energy to keep temperatures from falling quickly. Sounds interesting, and it makes sense as far as the physics of it go.
The composition is of tiny encapsulated wax globules suspended in the gypsum board. The wax can change from liquid to solid without affecting the properties of the wallboard.
Website: BASF-MICRONAL
Anyone else heard the good, bad, and ugly about this stuff? I wonder how all that wax affects the vapor permeability of the drywall.
zak
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone.” –John Ruskin
“so it goes”
Replies
So you have a gooey wall at anything over 73 degrees...
And wouldn't you eventually have a gooey floor at anything over 73 degrees ? That melted wax is pretty much gonna want to ooze on down to the floor, right ?
You can never get ahead by getting even.
Well, apparently the wax is encapsulated in such small particles that the phase change from solid to liquid doesn't affect the structure of the board. Most of the board is still gypsum, after all.zak
"When we build, let us think that we build forever. Let it not be for present delight nor for present use alone." --John Ruskin
"so it goes"
I know little about this, but the first thing that jumps out at me is the phase change only helps when you cross the threshold. what happens when you are consistently above or below the temperature change "pivot point"?
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
More material makes the change. Of course there is a limit.But lots of energy, relatively speaking, is need to make the change and that will keep the temp down as the change occures.
Edited 9/29/2006 10:37 am by BillHartmann
Hi Bill,I guess what I'm saying is, say it's january here in maine; we haven't seen 73 degrees in two months at that point, and we won't see it again for another two. It can't be very helpful in that case, could it? Maybe I"m missing something. Or maybe this is intended for more mild climates..?-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Yes, if you look at the examples they are talking about DAILY tempature cycles.http://www.micronal.de/portal/basf/ien/dt.jsp?setCursor=1_290814But even in a cold climate it could be used for a pasive solar system. Or maybe some other type of more bulk phase change material.
You're right, that it doesn't help you if you're below the threshold temperature. It's not a perfect replacement for mass. But how does a large mass of concrete at 55º help you if you want the house at 72º? I can see that it slows down further cooling, but it also slows down heating. That's the nice thing about this product- it won't slow down heating until you're at an average room temperature.
Not a silver bullet, and I haven't used it of course, but I think there could be very good applications for it if and when it is available here.zak
"When we build, let us think that we build forever. Let it not be for present delight nor for present use alone." --John Ruskin
"so it goes"
First thought is "how much a square ft will that cost?"
"... just as easy to work with as conventional wallboard..." Hmmm.
I just can't imagine something melting and cooling not moving around and causing pops or cracks.
I'm all for technological advance though.
And how green is a polymer sphere produced by BASF Chemical Co.
"microencapsulated phase-change material" don't sound to organic to me, a long way from hay bale walls. : ^ )
Mike
Trust in God, but row away from the rocks.
Number I heard tossed around was 3x normal drywall for the board. Installation should be the same. somewhere around 20-25/sheet for 4x8.
As I'm sure you're aware, numbers like that are pretty small compared to the cost of building a nice "green" house or apartment unit in california- the example that this talk was about was in Santa Barbara.
They were doing a few major upgrades from a standard house- SIPs (10 1/4" walls, 12 1/4" roof), triple glazed low-e windows, and the phase-change drywall.
For the 1200 SF top unit, the changes added up to about $16,000 increase in price. The savings in boiler size, etc. weren't factored in. Those changes should make the unit need no heating or cooling inputs. The $16,000 increase is about 1% of the projected unit appraisal value, so it was a pretty good deal for them.zak
"When we build, let us think that we build forever. Let it not be for present delight nor for present use alone." --John Ruskin
"so it goes"
Some years ago I remember reading about someone who invented a coffee cup which utilized the phase change wax to keep coffee at a comfortable temperature longer. Kept waiting to see it on the market but have not yet seen it. Just did a quick web search and found the patent, but no cups for sale... According to the stats at the bottom of the page, the patent was issued in 1988:
http://www.freepatentsonline.com/4765393.html