Replies

1. 
   CloudHidden | Dec 26, 2004 09:55pm | #1

   I've found that the spherical shape will help a lot with structural integrity and wind resistance, but has little effect on energy consumption. We're heating floors moreso than air, so the volume doesn't much factor in. It does help with air flow and spreading light, it seems, but just shape hasn't made it less of an energy consumer...that comes from lower air infiltration, mass, etc.

1. 
   hasbeen | Dec 26, 2004 10:22pm | #2

   Thanks for the input, Jim.  I was hoping that you'd comment about your experience.

   In conventional "flat" construction it's commonly recommended to have the ceiling insulated much more than the walls (even code reflects this).  I agree that stopping infiltration may be number one in bettering most building's efficiency.

   I'm not sure what you mean by "heating floors instead of air".  What's the air temp in your house?I'm thankful for the loyal opposition!  It's hard to learn much from those who simply agree with you.

1. 
   CloudHidden | Dec 26, 2004 10:48pm | #3

   I constantly run into that "R value of ceilings" thing, be/c we use the same amt of insulation everywhere. Have to explain it away and show that what really counts is loads, and ours run half or less of typical construction.As to heating floors...in my house, I think I'd use more btu's if I had forced air rather than rfh. Don't know or care about temp at the ceiling 25' off the floor. Only care about it around floor level, be/c it keeps my feet and body warm. With forced air, I'd be specifically heating areas I don't need to (the very high ceilings) and yet my feet would still be cold, be/c the floor would be room temp at best, and thus would draw heat from my feet. With rfh, the floor is warmer than the air, and nearly as warm as my feet, so I don't experience the cold in the same way.Look at it another way. If my ceilings went from the current 25' to 100', with forced air I think I'd use a lot more btu's, but with rfh I think it'd not be a lot more.

1. 
   hasbeen | Dec 26, 2004 11:02pm | #4

   I share your dislike of forced air heating.

   In my current house and one previous one, I approached the warm floor desire from the angle of having lots of sun warmed (passive) concrete and earth at the lowest level of the house.  Of course, our floors are never warmer than the air temp and my passive plan works as well as it does in large part due to the near-perfect solar climate I live in.

   I will always be looking at cost of heating compared to area heated while continuing to take perceived comfort into account as well.  Edited to add:  I'll be looking at cost of construction as a factor as well.  Friends who spent more than four times what we spent to build their slightly smaller passive solar save only a hundred or two $ per year over our ehat costs.  Hard to make back that kind of dough.

   I'm thankful for the loyal opposition!  It's hard to learn much from those who simply agree with you.

   Edited 12/26/2004 3:05 pm ET by Hasbeen

2. 
   MikeSmith | Dec 26, 2004 11:03pm | #5

   yes, but with forced air and returns at the top , you  can recycle that heat instead of letting it stratifyMike Smith Rhode Island : Design / Build / Repair / Restore

1. 
   CloudHidden | Dec 26, 2004 11:13pm | #6

   I won't suggest it works the same way in a frame house, be/c I don't know. But I think that the mass we have minimizes that kind of stratification. It's not something I've noticed, nor measured the one time I measured. Going further, it's something that I have specifically noticed not happening. All my comments are tempered (get it? r r r) by having a high mass building. Low mass buildings operate differently, and likely need different strategies.

2. 
   MikeSmith | Dec 26, 2004 11:49pm | #7

   well, you might be getting natural convection currents that are defeating the stratification..

    measure it again.. floor temp... 3'  above the floor... 3' below the ceiling .. and at the ceiling..be intersted in finding  outMike Smith Rhode Island : Design / Build / Repair / Restore

2. 
   jazzdogg | Dec 27, 2004 03:43am | #8

   Hasbeen,

   It sounds as though you're suggesting that, all things being equal with respect to insulation, air infiltration, the heating plant and even the heating method, the house with greater external surface area will be inherently less efficient than a house with less external surface area and the same internal volume.

   Makes sense to me, but wonder how much the added efficiency would be perceived or appreciated by the occupant. I guess it's a lot like the arguments about the relative merits of forces air versus in-floor radiant heat, espcially when the perceptions and preferences of the occupants are taken into account in addition to the cost of operation.

   Interesting topic.

   -Jazzdogg-

   Whether you think you can, or you think you can't, you're right.

1. 
   hasbeen | Dec 27, 2004 07:21am | #9

   That's what I'm sayin.

   I thought someone might know a link to something about it...I'm thankful for the loyal opposition!  It's hard to learn much from those who simply agree with you.

1. 
   Piffin | Dec 27, 2004 11:34am | #11

   What you aret alking about is referd to as the ratio betweeen exterior surface and interior volumn.

    yes, it is important in ref to energy design, but as Junk points out, a plain cube is un appealing to the buyer 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

3. 
   junkhound | Dec 27, 2004 07:36am | #10

   • You are essentially correct on basic physics/engineering (where did the bullet/dot come from on this reply?)
   • There are some secondary effects in that a sphere has higher bouyancy driven air velocity over the outer skin, so a perfect sphere is not the absolute optimum for an uninsulated shell, but close.
   • R11 or more in the wall makes the bouyancy effects negligible (like less than R-1 to R2 difference added for slightly non-spherical to reduce  bouyant air velocity over the average surface )
   • The real estate guys/gals just want to turn the house, long term efficiency means squat to them, whereas lots of neat little cubbyholes and interesting corners help sell on emotion. etc.
4. 
   GoldenWreckedAngle | Dec 27, 2004 06:42pm | #12

   I saw a report recently that M&M candy has now been scientifically proven as the most densely packable shape on the planet. NASA is adopting the shape for items they are packing into the shuttle. Appearantly the greatest volume contained within a given surface area can best be achieved with an M&M, spherical, disk type shape.

   It would make for an interesting style of building, that's for sure. Just a little food for thought.

    

1. 
   xMikeSmith | Dec 27, 2004 06:46pm | #13

   i always knew sphere was densly packed and tightly wrappedMike Smith   Rhode Island : Design / Build / Repair / Restore

1. 
   JohnT8 | Dec 27, 2004 07:32pm | #14

   i always knew sphere was densly packed and tightly wrapped

   ha ha, but he isn't on this thread!

    jt8

1. 
   VaTom | Dec 28, 2004 03:11am | #15

   ha ha, but he isn't on this thread!

   No, no, no.  He's everywhere, omnipresent.PAHS Designer/Builder- Bury it!

2. 
   hasbeen | Dec 28, 2004 03:37am | #16

   I think there is a house that shape - with an edge "cut off" - somewhere.  I remember seeing a picture.

   Plain or peanut?I'm thankful for the loyal opposition!  It's hard to learn much from those who simply agree with you.