Green Building Elements

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A South African company called Moladi is promoting their system for quickly building homes. Using their system, the exterior walls for a single-family dwelling can be built in a matter of just a day or two, and it can be done using unskilled labor. But, while their goals are admirable, it’s a question whether or not this is a really green method of building.

The system uses lightweight formwork panels, much like those used for poured concrete walls. Once erected, the forms are filled with mortar (concrete without stone) which can be hand-mixed and hand-placed, or which can be mechanically mixed and pumped into place. Typically, the formwork can be removed the day after the mortar is poured. The result is a smooth finish material, little more than a roof is needed to complete the building.

On the downside, this material uses 250 kilograms of portland cement per cubic meter (about 420 pounds per cubic yard), making it fundamentally the same as a concrete building with an enormous carbon footprint stemming from the extensive use of cement in these buildings.
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There is a new material touting itself as a structural element in the construction industry: bamboo.  It has been used for years in Asian countries, and is now making its way to the western world.  In fact, it has been certified by the ICC Evaluation Service to be a legitimate structural element.

Bamboo can be used in wall, roof, and floor trusses, or as individual studs.  The poles generally range in size from 2 ¾” to 3 ¼” in diameter and 10 to 14 feet long, so they will easily fit into standard western construction.  According to the ICC report, they can be used in Type V non-fire-resistance rated residential and commercial construction.  In commercial construction use is limited to one story and a maximum floor area of 2000 square feet.

Bamboo makes an excellent substitute for traditional wood framing because of its rapid growth cycle.  The largest species, timber bamboo, grows to a whopping 120 feet with a 13 inch diameter in just three years.  The stalks can be cut, then left to grow again without replanting.  Growing bamboo is good for the soil as well, as it deposits minerals into the ground, and serves to prevent erosion.

The down side of this new product is the cost of transportation.  Currently the only bamboo certified for structural use comes from Vietnam and must be treated with borate.  Bamboo can be grown in almost any climate, so costs could be reduced as more is grown in the U.S.  Locally grown bamboo would also help sales of other bamboo products such as wood flooring and veneer.

To see a building in Mexico City build from structural bamboo, visit http://en.wikipedia.org/wiki/Nomadic_Museum.

More on bamboo products: www.bambooliving.com

More information on structural bamboo: http://www.toolbase.org/Construction-Methods/Wood-Framing/structural-bamboo

To see the ICC Evaluation Service report, visit http://www.icc-es.org/

Editor’s note: this piece has been contributed by guest blogger Kevin Hughes. Kevin was generous enough to share his own experience with installing a solar hot water system on his home. Thank you, Kevin!

I live in Los Angeles and I prefer the ugly one! Please don’t get me wrong, my wife is very beautiful, but when it comes to solar power, I prefer the ugly one.

Let me explain, for the past few years there has been huge interest in Solar Electricity (photovoltaic’s, PV, or solar panels), there are lots of incentives at both a state and federal level, there are often photo opportunities for politicians, gazing towards the future over a vast array or solar panels. But there are problems with this vision: solar electricity is expensive to purchase and install; it has a long pay back period; it converts sunlight to usable energy fairly inefficiently, and because of that, you need quite a lot of roof space or land to put up enough panels to power your home.

The ugly one that I prefer is solar thermal, specifically solar hot water, a much older technology. It is also much cheaper to install, much more efficient, and has a much faster pay back. It can even be a do-it-yourself project if you are reasonably handy. As for the payback, that’s easy: you don’t have to pay for 70-100% of your hot water heating costs, and with a clever tweak, you can save 10-15,000 gallons of water annually, and reduce your water and electricity costs.

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If you can’t tell, we’re pretty hooked on the latest and greatest in green prefab design. One big problem, though, is that there’s a huge amount of noise and not all that much action - plenty of fabulous prefab designs and museum / conference exhibits, but very few actual installations (and even fewer mid-market installs, which is where prefab has to go in order to make a true difference in our housing stock).

Finally, the log jam seems to be breaking. Several firms have begun to produce green prefab homes for real people in small but growing numbers. This past month, Marmol Radziner, a prefab company here in Southern California, made a splash with some pretty showy installation videos on local media outlets. These homes are either a) high end or b) for the firm’s founders, so they’re still a ways away from mass-market. But, the videos do a good job of showing what elements make prefab homes unique (factory construction, rapid installation, modular components) and at least to me suggest that they’re not all that far away from being able to replicate these installations on a larger and thus less expensive scale.

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Let me first preface this post with the following: I’m not a construction professional. I’m just a curious homeowner seeking out the best building materials for my home. With that said, I was familiar with three options in residential construction - concrete block, wood frame or the super green alternative, rammed earth.

Turns out there are new options that combine the wonderful qualities of Portland cement with recycled post-consumer plastics (Rastra) or recycled wood fibers (Durisol).

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