Posted by Zombie Wolf on August 2, 2006, 2:16 pm
You know, im not even going to bother to argue the thermal mass issue. It's
been well known for many years that thermal mass in such a structure will
collect heat during the day, and give it off at night, thereby stabilizing
the average temperature. The thermal mass will also give the heat off during
the day, as well. Barrels of water, masonry, etc, are commonly used for this
Your "thin tin" and "wall" theories dont work in the real world. Such a
structure will cool off rapidly, even if the sun isn't out for an hour.
Read just a few of the thousands and thousands of tomes written on the
subject, all over the web. The masonry in the structure will not make the
structure any "cooler" than the ambient air temperature in the structure.
No insulation in the top of the structure will mean that you will start off
a good bit colder in the morning, and have to make it up before you get any
real heat, since most of the heat built up during the day will be lost out
the top of the structure during the night. Heat rises, in case you havent
noticed. Also, this greenhouse glazing roof you keep talking about is also
going to let in the summer sun, which will make the shop intolerably hot in
the summertime. A good slope roof that shuts off the summer sun is highly
recommended if you dont want to fry in the summer.
Posted by nicksanspam on August 2, 2006, 5:13 pm
Sure... 54 F :-)
Posted by Zombie Wolf on August 2, 2006, 5:51 pm
Your 54 F figures are out to lunch, if he puts enough thermal mass into the
structure. That is all there is to it.
You know, all I need to prove my point is my old cat. At the bottom of the
house steps, there is a big old rock, the sun hits it all day. its not even
black. Now, if i look out there ar night, even as late as 2 or 3 AM, you
will find the old cat lying on the rock at the bottom of the steps. The
reason ? The rock is still warm from the sun on it all day long.
Today, i went down to the local wal-mart. Now, I could have probably fried
an egg on the pavement in the lot. Ever lived in the ciry, where everything
is concrete and pavement ? It doesnt cool off at night, like it does out in
the country. Gee, I wonder why that is ? Yep, some people just like to
disagree for the sake of disagreeing.... so thermal mass doesnt work. Next
time you go down to wal-mart on a 90-degree day, kick off your shoes before
you go across that "cool" pavement... You will get a real quick lesson in
thermal mass, my friend..go down again about 9 PM , and see how much that
pavement has "cooled off"....
take a trip down to your nearest large city on the same day, and take a
temperature reading right in the middle of the day. Compare that with the
temps out in the country. You will find that the city temps are a good 10 to
15 degrees hotter. Why ? because the thermal mass of all that pavement and
concrete is re-radiating that heat right at you. Take a stroll down those
sidewalks at night, and begin to realize that they have failed to cool off,
even late at night....
If your theories about thermal mass "making it cold" had any credence, those
sidewalks would be COLD...... And we could get free cooling from thermal
mass. And people wouldnt be dropping dead from the heat in the city every
time the power grids fail... yep, the sun rises in the west, night is day,
and up is down... as you like it.........
Posted by Jeff on August 2, 2006, 7:17 pm
Zombie Wolf wrote:
I assume you mean this:
<quote zombie wolf>
The alternative here would be to build somethng similar to a greenhouse all
along the south side of the shop and then incorporate enough thermal mass
(like masonry) in it to heat the shop, keeping in mind that on heavily
clouded days, you will get nearly no heat output from it. this of course
wpould have a concrete floor about three inches thick to begin with. The
house system would be seperate from this, and would use collectors.
The thermal store is losing heat back through that "greenhouse" wall all
night (all day too, but night losses will be much higher). That's a lot
of loss through that large R2 glass wall. Considering all that loss, you
should get nearly Nicks 54 F. That R60 ceiling will be cold comfort
next to that R2 wall.
Gary's shop heater seems nearly ideal for this app. You eliminate
that big lossy R2 surface. Seems like a mix of windows for the daylight
you need, thermal syphon air collector for shop heat, and solar water
collector for the house and other needs. Storing and moving heat by
water is a lot easier than any other way.
Last time I was up north in the winter the concete driveway had no
problem collecting snow, even though it had been in the sun all day and
Average, average, average...
Posted by Solar Flare on August 2, 2006, 9:31 pm
Thermal mass does work, in most cases, but you have to control the
input. When you burn your feet on the hot pavement you prove it works
because you put the surface out to absorb as much heat as you can. The
idea is to work toward the result you want and not the opposite. This
is basic engineering practices. Think about it.