Beyond the Prius: Wozniak looks to green building

[zenMachine]

“You build a home out of a type of wood that keeps the temperature constant without air conditioning or heaters. The miracle wood in this category is Southern Yellow Pine. As for renewable resources, more Southern Yellow Pine trees are planted each year than are used. I’m told this is the only tree with this benefit. The Southern Yellow Pine has a resin inside that melts and freezes at 71 degrees F., a very comfortable temperature for humans. The chemical actions of melting and freezing work to balance the temperature. If it’s a hot day, some small amount of the resin melts (it takes a huge amount of energy to melt a tiny amount) and the melting process pulls heat from the surroundings, from the home. When it gets colder at night, the resin-wood emits heat as it freezes.”

http://www.ecorazzi.com/?p=3724

[SSimon]

All that resin - fire hazard, no? Does the wood have to be treated with a fire retardant and if so, what are the environmental drawbacks here? If none, this is quite a find.

[TSaxman28]

<div class='quotetop'>QUOTE(zenMachine @ Aug 24 2007, 05:12 PM) [snapback]501726[/snapback]</div>

“You build a home out of a type of wood that keeps the temperature constant without air conditioning or heaters. The miracle wood in this category is Southern Yellow Pine. As for renewable resources, more Southern Yellow Pine trees are planted each year than are used. I’m told this is the only tree with this benefit. The Southern Yellow Pine has a resin inside that melts and freezes at 71 degrees F., a very comfortable temperature for humans. The chemical actions of melting and freezing work to balance the temperature. If it’s a hot day, some small amount of the resin melts (it takes a huge amount of energy to melt a tiny amount) and the melting process pulls heat from the surroundings, from the home. When it gets colder at night, the resin-wood emits heat as it freezes.”

http://www.ecorazzi.com/?p=3724
[/b]

Take a look at this site as well: Enertia Homes

[madler]

<div class='quotetop'>QUOTE(SSimon @ Aug 24 2007, 02:40 PM) [snapback]501736[/snapback]</div>

All that resin - fire hazard, no? Does the wood have to be treated with a fire retardant and if so, what are the environmental drawbacks here? If none, this is quite a find.[/b]

According to wikipedia ( Longleaf Pine ), the trees and leaves are highly fire resistant. In fact the forest service sets fires in order to restore this species, since the fires kill everything except this tree!

On the other hand, the dead stumps and roots of this tree are highly flammable due to a very high concentration of the resin.

I found no reference for the flammability of the lumber itself, but of course all wood construction has that issue.

According to someone trying to sell the stuff (so take it with a grain of salt), "Southern Yellow Pine is grown in sustainable forests and is environmentally responsible."

[fshagan]

Southern yellow pine (SYP) is farm grown, and harvested before you get to the darker "heart wood". Its still a great wood for boat building, and has some natural decay resistance for things like fence posts, all due to that resin content.

But ... I don't think that lasts forever. There's a huge difference in cutting through "green" SYP and kiln dried SYP. The green SYP still has a lot of water and sap in it. The kiln dried lumber, which is usually what you would use to build a house, has a low moisture content and much less sap. I've cut into some 100+ year old SYP, and it is dry as a bone.

Its possible that the SYP still has sap in it that my unscientific experience can't detect, but we've known about the R-value and thermal mass properties of SYP for a long time. So I take some of this stuff as "puffery" and not hard, scientific fact.