Friday, June 6, 2008

LEED update

We met with two representatives from the ECA (Energy Coordinating Agency) - our LEED for Homes provider - last week to walk the project for the first time. It was a good time to really see some progress as the contractor had just removed the roof. They were excited to see the reality of what we had only been discussing on paper up to this point.

We started in the back yard with a discussion about erosion control during construction. Currently, we were not providing any physical barrier at the edge of our property that would prevent material run-off from traveling into the neighbors yard and the street. Seeing that the back yard had been filled with a lot of debris until just a couple of days ago, it would have been difficult to set up any kind of prevention system. But now that the rear yard is clear, we can accomplish this. Usually, erosion control is taken care of with what is called a 'silt fence' - a kind of fabric fencing that allows water to pass through but prevents dirt and debris from traveling through. Seeing that this is such a small application, an alternative was offered up: Straw bales. We will place bales at the perimeter of the rear yard and at end of the alley where is meets the sidewalk. This will help contain our run-off and prevent any further erosion.

Next, we discussed the insulation of the house. I explained that we will be using the BioBased spray foam insulation throughout the entire perimeter of the house (including the existing basement walls and the new crawl space) except the roof where we are placing 8" of rigid insulation on top of the roof decking. The main reason for the rigid, opposed to the spray foam, on the roof is that we want to expose the structure at the third floor ceiling. In regards to the insulation, we are essentially talking about two things: the R-value (Thermal Resistance) and the 'tightness' of the building envelope. The minimum values we are looking to achieve are roughly R-20 for the walls and R0-40 for the roof. The closed-cell spray foam at the existing brick walls will will give us about R-20 and at the new wood stud walls, about R-30. The foam also doubles as our vapor retarder. The 8" of rigid on the roof (insulation only) will give us R-40, and it only gets better as we add material (decking) and if we end up having a green roof, that will help even more. This level of insulation, along with the Kolbe windows, which are achieving a U-value (Thermal Conductivity) of .34, will provide us with a very energy efficient building envelope. Of course, it is also very important for us to detail the connections of where all of the different surfaces meet each other so as to prevent any leakage. The reps from the ECA were quite pleased with the way in which we were tackling the energy-efficiency in regards to insulation.

I then pointed out all the salvaged material (heart pine flooring and wood joists), along with the old claw foot tub, in the basement that we were storing for later use in the project. Also, at this point they were able to see that all the lumber used in the construction was either FSC Certified or reclaimed. Lastly, we discussed the layout of the mechanical system and they offered some suggestions and examples as to how we could improve the efficiency.

In the end, it was a great initial site visit and I think everyone now has a better understanding of what we have we have done so far with the project, what we are doing now, and where we are going.

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