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Re: Plastic Dome Doghouse -- Leaky - Page 2

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Posted by gary on February 16, 2008, 6:44 pm
 
On Feb 16, 3:31 am, nicksans...@ece.villanova.edu wrote:

Hi Nick,
Helpful calcs on the dog house -- thanks.
Where does the ASHRAE dog data come from? The fundamentals volume? or?

I've been working on a solar dog house -- some results to date:

Control Igloo House:
My control for the new doghouse is an igloo style, uninsulated dog
house with an improvised heavy cloth door.  It has a 40 watt bulb
inside to simulate dog heat.  It is worthless.  The only time the
temperature in the igloo goes above ambient is for an hour or two a
day when the sun is shining directly on the door, otherwise it tracks
with a couple degrees of ambient even when the 40 watt dog is on.  I
suppose it provides some wind protection, but thats about it.

New Solar Dog House Prototype Description:
The prototype solar dog house is wood construction.
Insulated to an average of about R12 on all sides, ceiling and floor
-- mostly 2 inch polyiso.
Floor is single layer brick for thermal mass (insulation below this).

Entrance is a tunnel arrangement with commercial heavy poly dog
flapper doors that seal fairly well -- one on each end of the tunnel.
First entrance is part way below 2nd for some, but not enough for full
thermal trap.

Inside space is just large enough for dog to stand in, turn around,
and lay down to minimize heat loss.  Roof is flat to minimize volume
and provide a place to dog to lay around on roof.

"South" wall is about 80% glazed (a high fraction of floor area).  The
glazing is homemade double Acrylic that seals well.  The house is on
ball casters so that the "south" window can be turned to the north in
the summer to prevent overheating.

I'm planning on adding solar chimney in summer.

Performance:
As mentioned, the Igloo is near to worthless, and just tracks ambient.

The protoype solar behaves better, but well short of perfect.
On a sunny day, temp inside the dog house can go up to as high as 110F
even when ambient is 20F.  Too much glazing for the mass.  This day
overtemp may not be a serious problem in that dogs spend day mostly
outside.

At night, the prototype maintains about 15 to 20F over ambient.  The
effect of the dog simulating 40 watt bulb can clearly be seen on the
temperature plots -- there is a distinct reduction in temperature drop
rate when the light goes on -- so insulation and sealing are good
enough to make a small heat source useful in heating the space.
I would call the current night performance marginal in a cold climate,
but much better than the Igloo.

Yesterday, I tried adding 10 gallons of water in black painted pails
to the house.  Positioned so they got sun through the window.  This
resulted in a big change for the good.  Peak day temp was down to 90F
where it would have been easily been over 110F.  Night time
temperature drop rate was less than half the previous rate.  Morning
temp was nearly 30F over ambient and a comfortable 55F.  I guess (not
surprisingly) that mass helps.

Problems/Questions:
Brick floor is undesirable, but putting a pad over the brick means the
brick mass does not get direct sun.  How to get good solar transfer to
the mass and still have a good sleeping surface?

How to add more thermal mass without taking up too much space?

Would I be better off with less (maybe much less) glazing, and just
rely on dog heat + good insulation + thermal mass to even out the
temperature and keep it enough above ambient for dog comfort?  This
seems like it might have some benefit on strings of cold, cloudy days
as well?

I'd like to hear more about the "condensing double wall thermal
chimney"

Not sure if when I add dog produced moisture if I can stand the
ventilation rate that will be required to control condensation?

Any ideas anyone has on making the design better?


Gary



































Posted by hallerb@aol.com on February 16, 2008, 7:28 pm
 
On Feb 16, 1:44pm, g...@builditsolar.com wrote:

dogs should live indoors with their family. not outdoors espically in
too hot cold wet or snowey weather. we have 3 furry friends they have
dog doors, and a fenced in yard for their protection.

dogs forced to live outdoors, thats just plain cruel!!!!!!!!!

Posted by Davej on February 16, 2008, 7:30 pm
 On Feb 16, 12:44 pm, g...@builditsolar.com wrote:

I don't know much about solar heat. I think your excessive daytime
temp demands a redesign. Rather than making the house a solar
collector you could perhaps build the house over a plastic tank of
water and then circulate the water through a solar collector during
the day (south wall of doghouse?). Maybe convection flow would be
possible.

Another natural organic approach -- I've heard that greenhouses were
once heated using a thick floor covering of composting manure. Maybe a
doghouse could be heated using that method?

Posted by gary on February 17, 2008, 6:30 pm
 
That seems a bit complex for a dog house?
Dogs are pretty sensible about just moving to a more comfortable
location when things get to warm or to cold.
I'm more concerned about trying to keep the night temp reasonable,
since the dog may have no other place to go at night.

Gary


Posted by Jeff on February 16, 2008, 9:56 pm
 gary@builditsolar.com wrote:

I don't think the brick is doing much. The specific heat of brick is
fairly low. Add another 5 gallons of water.

   Jeff




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