Might take a while to read through it but here is some info.
And there were several sites that talked about using electrically heated marble, so there must be something good about using marble !
The "Which Rocks Absorb Heat" article mentions that two types of rocks may be best for a given application. That is precisely what I am trying to explore, but I can't find anything about good combinations, or even where such a configuration has been tried, if anywhere. That makes this search fun. The concept of two types of stone with different thermal characteristics makes good intuitive sense to me, but I struggle with interpreting the tables showing material density, heat capacity, thermal conductivity, etc. Are there any Science Teachers out there who can help?
Thank you again, Miles. I was very pleasantly surprised to see a notification from Permies that a reply had been posted!
To put it a nicer way, take all the time, money and effort that you would be spending on extra thermal mass and put it into air sealing, continuous insulation and possibly windows. Most of the science and experiments into thermal storage have played out since the 70s and 80s when people first started figuring this stuff out. Do a 4" concrete slab (or equivalent earthen floor) insulate all around it and call it a day. Most passive solar designs dont provide enough BTUs to heat more mass than that in a given day so there is no point in spending extra to try to squeeze out more performance in that area. Not with so much lower haning fruit around. 12% high shgc glass to floor area and a slab on grade. Simple. Maybe a slab on the upper level too or a real stone accent wall but the cost effectiveness is debatable.
Air sealing on the other hand is incredibly effective for what you put into it. Some homes are so airtight and super insulated that they can maintain comfortable temps from body heat, appliances and lighting with no passive solar or any other energy input.
Hope Iam not missing something here. You are planning on a mass floor right? Your not trying to actively circulate solar heat to mass storage bins are you?
Rebecca, covenants I will have to follow disallow earthen buildings but I do appreciate their thermal properties combined with low-embodied energy. Good for you and again, thank you for your comment.
Finally, sincere kudos to PERMIES for helping me make these connections!!
It is a challenge to open high performance structures to the outdoors in certain climates at certain times of the year but I think its worth it to sacrifice performance for enjoyment of home, nature and life in general. Ive been hearing about some of the work University of MD is doing but I havent found or sought out any real info on it other than some short blurbs about it in articles about their solar decathalon entry which I think is the leaf house? Would appreciate any links more specific to the technical side of what they are doing if you or anybody else has them.
I hear you on the Vanderbilts and people from that time period in general. How in the hell were people always wearing wool suits back then!? In the summertime with no AC. I just dont get it.
Bill Tucker wrote: My challenge, though, is that I ALSO want to open the house up to the lovely outdoors (e.g. Nana-type doors).
.... I agree with you that humidity is my greatest challenge to address passively. Have you seen the Leaf House desiccant waterfall out of UMD? Not totally passive but very interesting. And I keep thinking that Vanderbilt and his summer guests were somehow ok without air conditioners and dehumidifiers. There MUST be strategies which work.
Rebecca, covenants I will have to follow disallow earthen buildings but I do appreciate their thermal properties combined with low-embodied energy.
Oh well. Earth buildings are also sort of magical in their ability to modulate humidity as well as temperature.
In my experience, growing up in centrally heated, well insulated wood frame houses in the US, and then 20 years living in passive solar earthen houses in the high desert, and also visiting friends' houses in Ladakh that are heated and have stone or cement slab floors and/or cement plaster, here's my opinion. The wonderful thing about earth or wood or plasterboard surfaces in the winter is that they are not highly conductive, so if you have to lean against them or stand on them in socks, they don't suck much heat out of your body. Stone and cement surfaces may be walls and floor of a reasonably heated room, ie room temperature, not icy cold, but because they are highly conductive, they suck the heat out of your flesh very quickly and make you feel cold at any point of contact (such as standing on the floor).
The more thermal mass your house has, the better it will sail smoothly through a couple of weeks of what would be heating or cooling weather in a wood-frame insulated house. That's how those ancient Indian palaces kept their occupants reasonably comfortable through the intense hot seasons, and warm through the brief but chilly winter.
About opening your house up to the outdoors -- be careful. If you put TOO much glass on the south-facing wall, especially without sufficient thermal mass blocking and soaking up the rays, you will suffer from daytime overheating, especially in the autumn and winter. It's really not comfortable to have overheating.
Re opening up the house, I do not intend to exceed Brian's glass-to-floor ratio. And I envision a vine-covered trellis to block summer and fall sun. What I meant about opening the house up was sliding glass walls such as these: http://www.nanawall.com/ I feel that there must be a reasonable, cost-effective alternative to sealing oneself off from the outside. Air-conditioning has only been around for about 50 or so years...
I particularly appreciate your comments about cement and stone floors, the apparent materials of choice for thermal mass. And yes, I definitely prefer the thermal mass approach and see that Ladakh weather is harsher than where I intend to build, so their bulding experience is important.