Wednesday, August 15, 2007

Wozniak's New Goal is Efficient Housing

Interesting interview with Apple co-founder and legendary hacker Steve Wozniak where he talks about building an energy efficient home using Southern Yellow Pine which has a natural property of heating and cooling homes, eliminating the need for A/C and heating. He also takes about a company called Enertia that has kit houses made of Southern Yellow Pine, ready to assemble without using any nails. This is a really intriguing idea!
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.

In high school chemistry we had the latent heat of fusion concept. You let ice settle in water. You can measure the temperatures. The ice and water are both 32 degrees F. It seems like the tiniest amount of energy would cause the ice to melt. After all, you only have to change it maybe a hundredth or less of a degree. But it takes a huge amount of energy to accomplish melting. This represents the difference in energy between the solid and liquid states. In this way, large amounts of energy can be stored. In the case of Southern Yellow Pine, energy from the summer can even be stored in the wood until a later season in some cases.

This company Enertia prepares blocks of this Southern Yellow Pine with grooves and sells the pieces as kit homes that you build yourself. The only tool you need is a power drill. No nails are used in the construction. I suspect that's because the metal of nails helps outside temperature conduct to the inside. The homes are also designed in an envelope fashion with 2 layers of wood and a space between them for natural air circulation around the home. The Southern side is all glass to collect sunlight. The homes are designed for more sunlight getting in during the Winter, when the sun is lower in the sky, than during summer, when the sun is higher in the sky.

All of these simple principles wind up with a very attractive house that is as normal and livable as any other, but without insulation or air conditioning or heating. The typical energy bill might be as low as $30 a month, depending on where you live. The outside temperature can be 50 degrees hotter or colder than the inside temperature of 71 degrees.

Recently I bumped into the builder of my first home. We reminisced and I told him of my plans to build one of these Enertia homes. He had built many homes with the efficient ram-dirt process and for one of them he used the resin-wood (presumably Southern Yellow Pine) for the roof. With only the roof being of this resin-wood the temperature inside never varied more than 5 degrees he told me. So the combination of approaches is one thing I'm considering too.

Wozniak's New Goal is Efficient Housing

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