June 6 , 2004
Design and Construction of an Eco-house
As you may recall, students and faculty from Carleton College came to visit our cordwood home at the end of April. (See the May 2nd Journal.) The students were conducting an energy study on various forms of green construction methods: straw bale, cordwood and rammed earth and were anxious to see our house-in-the-making. It was quite a coincidence that they were in the process of building a double-cordwood wall while we are building our own double-cordwood house. As far as I know, our house is the only double-cordwood structure here in the U.S. and they were able to view the walls prior to completion.
During their visit, the instructors: Richard Strong and Gary Wagenbach invited me to their final class presentation to be held on June 1st of this year. I was most eager to attend the presentation since this is the only R-value test ever done on a double-cordwood wall.
I arrived at Carleton College a little bit ahead of schedule and walked about their campus. Carleton College is a private liberal arts college located in Northfield, Minnesota with about 1,800 students. I found their campus to be quite beautiful with plenty of old trees and interesting sculptures. I was quite impressed by their campus, instructors and students.
Their presentation was broken down into four sections: conventional, straw bale, cordwood and rammed earth wall construction. Faculty and students each gave their presentations that not only included R-value information, but also their embodied energy. Embodied energy is something that is quite often overlooked when studying different styles of construction. No matter what the form of construction, there is a certain amount of energy required to produce the wall. This is not a trivial matter. Depending upon the materials used in the construction, the embodied energy can be rather low or rather high based on how much energy it takes to make the building materials, transportation of the materials and finally any machinery/manual labor that it takes to actually construct the wall. Cordwood has a lot of embodied energy. This is especially true if the walls are made with mortar without any additives such as sawdust or recycled paper.
I certainly enjoyed the conversations that I had with the students as they came to some of the same conclusions that I have while constructing our house. There are many trade-offs that have to be made during the construction process. Trade-offs that involve weighing green building materials vs. somewhat green building materials. Do you build a wall that is totally organic in nature or do you add materials that make the wall more efficient but not as green? Does the reduction of energy consumed over a 60-year period to heat a house offset a less green building material? These are questions that aren't always easy to answer, but I certainly applaud the students and faculty at Carleton College for attempting to come up with the answers.
Their presentations were quite thorough although I got the impression that they were really pressed for time during the construction phase of the walls. It also appeared that they really didn't have enough time to test and retest their results. For that reason, I will not divulge the test results at this point. The faculty at the college plans to retest their results next winter. This should give ample time for the walls to completely cure. There is certainly quite a bit of moisture in all of the green building materials that they tested and until the walls are completely dry, I wouldn't want to speculate.
One thing is for sure, it would be nice to see more colleges taking an active role in green building, renewable energy and other earth-saving matters. As one student put it, there are over 6 billion people on this planet and we are consuming 3.5 earths-worth of natural resources in order to sustain the world's population. Obviously, this cannot continue and it's comforting to know that Carleton College is doing something about it.
On Wednesday afternoon, the state's electrical inspector came out for the inspection and okayed the system. He was still a bit reluctant to pass inspection of the the system since this was the first one of its kind that he ever inspected. He conferred with his management regarding the system and at 8:30 on Thursday morning, the system officially passed inspection.
I then made an appointment with our local electric utility to fill out their application, state-wide contract and provide them with a check for $200 to cover the cost of paperwork and for the installation of a bidirectional, digital meter.
During this whole process with our local utility I neglected to fill out the official application. (My fault.) It states in paragraph 1.2 that the application for interconnection should be filed not less than 30, nor more than 90 days prior to the proposed date of an interconnection. I am not quite sure what impact this will have upon the final approval of the system, but the ball is now in the hands of the local utility. Since they have had the system diagram for quite some time and have visited the premises, I can only hope that they may approve the system shortly.
In the mean time, I have been busy writing the application that will extract data from the inverters and post hourly statistics right here on the web site. As soon as the system is approved and generating power, you'll be able to view our solar electric system in action.
A White-Throated Sparrow poses for a picture.