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O.K. so now it is my turn to shed some light on how I spend my time here at LJUrban. I am responsible for ensuring that we build the highest quality sustainable construction we can afford to produce. There are other things too but I thought I would concentrate on the “Green Building” aspect for this post and hopefully follow up with other new innovative ways that people are building sustainably as I come across them. We have not yet been able to define precisely what feature will be included in our homes. Each project will have its own eco-friendly features and hopefully each will progress with a greater shade of green until we are able to create truly ecologically balanced communities.

So, as I had mentioned in a previous post, I recently finished a course at UC Davis on Sustainability and the Built Environment. I was tasked with researching and writing a paper and giving a presentation on something in that field of study. I chose to research “Sustainable Structures” that are primarily dependant upon concrete for strength and durability, and compared four systems for various factors related to energy-efficiency, sustainability (recyled or reused content) and durability.

Green Sandwich Technologies 2006

The results you ask. . . well, in my opinion, one of the coolest products out there right now is called the “Green Sandwich Panel.” It consists of a core (made of either foam or biomass) surrounded with a steel wire cage encased with concrete plaster. The panels are erected by hand, tied together and then a spray-applied concrete plaster system or shotcrete is applied.

SCIP’s maximize the thermal mass effect, which translates to greater energy-efficiency. The presence of concrete surfaces on the interior and exterior of the structure separated by an insulating core allows a thermal flywheel behavior to take place. When the interior of the house is heated or cooled the wall system absorbs that heat or cool. When the temperature in the house changes, the walls will begin emitting the retained heat or absorbing it as the case may be. The exterior skin behaves in the same manner by preventing the heat or cool to radiate inward. Their energy efficiency is maximized in warmer climates, especially those with large temperature differences between day and night, like the deserts of the southwest, where homes built with thermal mass walls (including traditional adobe structures) have been most popular. Structures built using these technologies can be designed to require a significantly smaller heating and cooling system or possibly no cooling system at all.

The Green Sandwich SCIP panel utilizes very sustainable materials. Green Sandwich panels are made from 40% recycled material content by weight, and 60% by volume. All waste is 100% recyclable. They use BASF’s environmentally-friendly Styropor EPS foam in the panels. “The wire mesh is 40% recycled steel (Mostly from the auto industry), and the shotcrete skins are a minimum of 40% fly ash (A byproduct of coal burning). Green Sandwich Panels can be fabricated with a core of 100% locally harvested biomass. The source of this bio-mass can include “rapidly renewable” content, such as orchard trimmings, road-side weed growth, straw and stalk mowings.”

From the standpoint of durability these systems rival that of a precast concrete system. The insulation materials are isolated within the concrete envelope and therefore are not as susceptible to moisture, termites, or physical damage.

The SCIP structural system appears to be the most holistically sustainable option for construction of residential housing. The Green Sandwich panel exceeds the renewable and recycled material content of all of the systems analyzed. Either system if used broadly would reduce lumber consumption, energy consumption, carbon production, and building waste.

Micah