[Greenbuilding] [BULK] passive solar homes - floors

[Lawrence Lile]

Mazria's books are the Bibles.  The physics of solar energy hasn't
really changed in the last 20 years, just the materials.  This book has
great guidelines for things like ratio of South Glass to floor area,
other rules of thumb.  He cautions you to check the rules of thumb with
accurate modeling, but start out with the rules of thumb as a rough
estimating guide.  


Concrete floors are definitely hard on the feet.  I have one, and my
feet hurt when I walk barefoot on it, both from hardness and coldness.
I have measured the temperature of the floor many times with a surface
thermocouple.  The floor is always the same temperature as the air in
the room, but is FEELS cold because it is a better conductor of heat.
I'm happy with it, cuz I wear houseshoes around the house, but your
client may not be. 

Concrete floors will almost always feel cold, even in an intense
sunbeam, in my experience.  If a concrete floor is 80F, it still feels
cool to the touch.  A wood floor feels warm, because it is a poor
conductor of heat. 
  

Tile over wood framing is an idea for mass.  You can also use masonry
finishes in the room, such as a big brick object, brick on the walls,
concrete block walls, stucco.   A solar contractor I know expands the
mantelpiece (which is usually designed around a wood stove rather than a
fireplace) into long shelves, room dividers, and so on to add mass.  You
can double sheetrock for mass.  There are many ways of getting enough
mass without resorting to concrete floors.  If they love wood floors,
then give them wood floors!  


Biggest common mistakes in solar:  

Not enough south glass
Too much south glass compared to the amount of mass
Using heat reflecting or Low-E glass on the South
West windows without shading
Underinsulated slabs
Using boxes of rocks, hollow concrete blocks, or anything else that
can't be cleaned, to store heat.  
Paying too much attention to passive heating, and none to passive
cooling. 

--Lawrence Lile, LEED AP, PE

 
-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Kat
Sent: Sunday, June 10, 2007 11:18 PM
To: Greenbuilding
Subject: [BULK] [Greenbuilding] passive solar homes - floors
Importance: Low

Hi all,

I've got a client of my very own (my first!) and I'm trying to convince 
them to go with the simplest passive solar system - that of direct 
gain.  I've got a few questions:

1) I'm reading _The Passive Solar Energy Book_, by Edward Mazria, 
copyright 1979.  Is this generally a good source?  Is there another 
source I should follow up with, to fill in holes, or find correct 
information?

2) Does anyone on the list live in a well-functioning direct-gain 
passive solar home that uses the floor as part of the system?  If so, do

you happen to live in a temperate climate like Portland, Oregon?  And if

so, what do the floors feel like in the winter?  Are they warm, tepid, 
or cool on the feet?

3) Any suggestions for how to convince the client that they will like a 
thermal-storage floor, when they are a die-hard fan of wood floors, and 
think that concrete is going to be too hard?  Or is this going to be an 
impossible task because concrete *is* too hard?  Is it nasty to live 
on?  These floors would be joisted - the concrete (or dirt, or whatever 
I could convince them to use as thermal storage) would go on top of the 
joists.

Thanks!

-Kathleen

_______________________________________________
Greenbuilding email list
List info:
http://listserv.repp.org/mailman/listinfo/greenbuilding_listserv.repp.or
g
List email: Greenbuilding at listserv.repp.org
Managed by BuildingGreen, Inc. http://www.buildinggreen.com
      publisher of Environmental Building News and GreenSpec(r)
Hosted and archived by REPP / CREST http://www.crest.org