re: a strawbale doghouse SOLAR.KnowledgePublications.com

re: a strawbale doghouse
5 mar 1999
linda h. and the route 66 pack (lehunger@aol.com) continue:

>so.....two to three dogs, ranging from 110-160# each, housed together,

let's say 2 110 pounders, worst-case, with an average heat gain of
2.5x6.6x110^0.75 = 560 btu/h per dog, or a total of 1120 btu/h,
according to wood et al on page 9.12 of the 1993 ashrae hof.

>...and want to keep doghouse about 55-60*f inside, with average temps
>?15-20* at night...

let's say it's 15 f outdoors and we want 60 indoors, worst case.

>...can be how big??

the 1'x2' door has a thermal conductance of about 2 btu/h-f,
and r50 strawbales have 0.02 btu/h-f per square foot. with
60-15 = 1121/u, u = 25 btu/h-f, max. so... the door has 2,
leaving 23 for the walls. with s ft^2 of exterior surface,
at most, 0.02s = 23, so s = 1150 ft^2. an l foot square 8'
tall has l^2+4x8l = 1150 ft^2, not counting the floor, so
l = (-32+sqrt(1024+4x1x1150))/2 = 21.5 feet, maximum. wow. 

(this latter equation might well come from the squaw on the
hippopotamous being equal to the sons of the squaws on the
other two hides, were that not politically incorrect...) 

with this thermal budget, we might have an 8' cube with an
a ft^2 r2 window, where 23 = a/2, roughly, so a = 46 ft^2.
the window might be 8' wide and 4' tall, say 2 horizontal
strips of polycarbonate plastic along the lower south side,
with some strawbale beds so the dogs can sleep above the
cool pool of window air at night. 

>and btw.....doggies love to shred green plastic stuff,
>'speshully ifn it's full of stinky old leaves!!!!!

i guess that lets out the arched double shell plastic film 
version, unless there's something like burlap inside the
inner film. i'd start with dry leaves, and poke a few holes
in the bags to let the heat of the dogs keep them dry. 

a half-cylindrical greenhouse 8' long and 8' tall in the middle
with an 8x16' footprint and a 1' gap between the shells filled
with leaves with an r-value of 2 per inch has a conductance of
200ft^2/r24 = 8.4 btu/h-f for the curved walls and another 8.4
for the endwalls, leaving 23-16.8 = 6.2 for a 7.4 ft^2 double 
poly film window or skylight, ie a void in the leaf bag fill.

nick