Tuesday, June 16, 2009

A lofty project

To the left, I've added a link to a research paper I recently wrote on how this tiny house addresses issues / concerns of volatile organic compounds, carbon foot print and sustainability. It references U.S. Census data, Department of Energy data, and other academic sources, so it might be a bit dense. But, it has some terrific information for folks that want to talk up tiny houses.

As for the rest of this post, I just wanted to post a few pics of the loft area that Arlene has been working on over the last week or two.

In the pic above you can see the framing for the loft floor for the storage area. You can also see the porch post, which is about the only work I contributed over the last two weeks.

We have double blocks between the rafters/joists so that we have something to attach siding too on both the inside and out. The tongue and groove will go all the way the edge.

The next step is the sheathing. We'll put a post up on that in a day or so.


  1. How does your simplified R-value calculation differ from a UA calculation?

  2. This is a great question. The short answer is, apparently not much at all. Before reading your comment I hadn't heard of a UA calculation, though I do know that U-value is a heat transfer coefficient for some given substance, and is also the reciprocal of the R-value. So I did a very bit of poking around and – correct me if I'm wrong – UA is just the weighted sum of component U-values in a system. If that is correct, then my simple overall R-value calculation is the reciprocal of a UA calculation.

    What is somewhat boggling to me is that when I looked around on the net, I came across Coloradoenergy.org, which I list as a source of information, which has the following formula posted: Assembly R-value = 1 / (Assembly U-value) = 1 / (U-studs x % + U-cavity x %). Which is either new since I was last on the page (probably not), or else I didn't see it when I came up with my own system. Most of the reading I did on the topic came from the Department of Energy. When I started digging in to heat transfer calculations, particularly around corners and places where materials of differing substances come in contact, I decided that for this project, that level of detail wasn't important, so I just used a standard weighting method.

    Actually, if I had time, I think the calculations for heat transfer around corners would be pretty fun.

    Anyway. I altered my document and re-posted it so as to not take credit for creating something that is so similar to an existing system.

    If you have links to specific info on UA calcs, please post it here or send them to me.

    Thank you,


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