[Strawbale] re. Re: PEX, Concrete Slab, Fear of Death (by contractor)(Speireag Alden) (Speireag Alden)(Speireag Alden)(Speireag Alden)

[Speireag Alden]

On 2008, Jan 07, at 02:32, Shody Ryon wrote:

> Does earth-berming help insulate a house?

     No, but it provides a whopping amount of thermal mass.

     What earth-berming does depends very much on design.

     A simple earth berm, up against a wall, with no other  
detailing?  It will buffer exterior temperatures.  That is, it may be  
0°C outside, but it will take longer for that temperature  
differential to creep in to the interior wall.  Conversely, it will  
also take longer for 40°C temps to creep in to the house.  However,  
snow melt and rain off the roof will still percolate down through the  
earth adjacent to the wall, unless you draw it away with drainage.   
In this design, you would want to put insulation between the living  
space and the earth, usually on the outside of the retaining wall.

     An earth berm under a 20- to 30-foot umbrella of insulation and  
waterproofing behaves differently.  The run-off does not percolate  
through the area under the waterproofing, cooling things as it goes,  
and so the mass under the umbrella can only change temperature via  
conduction.  There is significant disagreement in building circles as  
to how this actually performs.  Some argue that you should couple the  
house to the earth when you do it this way, and not insulate  
immediately adjacent to the living space.  Others say this is  
foolish.  I agree with the first group if and only if you are  
charging the berm with totally renewable energy.  Otherwise I'm with  
the second group.

     If you insulate all around the living space, and bury the house,  
then your energy consumption will be less than an equivalently  
insulated house sitting on top of the ground.  The ground will buffer  
all extreme temperatures, reducing the temperature differential  
between inside and outside, and therefore reducing heating and  
cooling load.  There is no doubt about that.  The only controversy is  
about whether AGS and PAHS buried-umbrella systems work, and are  
worth the effort.

-Speireag.