Flooring

One of the biggest questions I've had about building a green house has been about flooring. As we plan to use a ground source heating unit and a passive solar design, there are certain issues for flooring. With radiant heating (from ground source) we need to consider the r-value of our flooring choices. If a floor covering is too insulating, the heat won't be able to transfer from the system to the room (or, for cooling, from the room to the system.) As far as I know, they recommend an r-value under 4.0 for radiant heat systems. For passive solar, you want flooring that can soak up the heat from sunlight coming through southern windows, then release the heat as the sun goes down.

For both of these systems, tile, stone or concrete work well. But, it's also my goal to make the house have a "historic feel" and "have a lot of character." In my aesthetic, these ideal materials fall short. Also, I really like having carpet in some rooms, both for its coziness but also because it keeps dirt from swirling about the house and causing an outbreak of dust bunnies.

So, I've been doing some research. Turns out, I may not need to sacrifice my style for the environment. A low pile, synethic carpet (r=.7) with a thin, slab rubber pad (r=.32) doesn't have a bad R-Value (total just over 1.) Linoleum (which I like for kitchens) has a typical r value of .4. Specifically, Marmoleum has a 2.45 value for the kind you install with adhesive and a 1.7 for the floating floor type. Hardwood floors tend to be around r=.7. Engineered wood flooring around .4.

At the same time, I'm shopping around for ceramic tile. Ceramic tile has a typical r-value of .25 (so, non-insulating) and is good as a passive solar mass. My hope is to find a tile that I really like and use that in the room(s) with the most southern exposure, while using flooring that I prefer for aesthetic or functional reasons in other rooms.

Just to keep myself organized, I'm pasting an e-mail from Marmoleum here:
"It will be fine to install either the Marmoleum sheet goods or the Click(our "floating" floor) over radiant heat. We do recommend having theheat shut off or turned down for at least 48 hours before installation,during and 72 hours after installation. It should then be raisedgradually, so adhesive and material can cure/adapt together. Thesubstrate temperature should never exceed 85 degrees. The R-Value of theMarmoleum sheet goods is 2.45, and the Click with a vapor barrier (whichwill be needed when installing over radiant heat) is 1.70.Please let me know if you have any additional questions. Jennifer Malloy Technical Services"