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<div class="moz-cite-prefix">Finally 'found' the time to read all
your great mails on this 'massive' subject written in the usual
'light' GSBN manner and would like to share a few things that came
to mind. <br>
<br>
I find this a subject that is simple and complex (to calculate) at
the same time. So I too use the 'intuative observation' approach
(by lack of being able to tap my brain intto Luc's).<br>
<br>
Laura's question : what we might lose in having wood rather than
exposed plaster.<br>
<br>
My gut-response is that if you perfectly master/regulate the
amount of calories to enter and leave your building according to
the desired confort you would not need any mass. But this
regulation of calories is complicated (and that always seems to
mean expensive) so adding mass (plaster 'protected' by insulation)
allows us to store the excess heat or cold and let it flow back
when usefull. Ofcourse, plastering also has its cost (and drying
time). The question is probably which of the 2 solutions is the
cheapest way to go; but one cannot, as we say in France : "have
the butter and the money" (for selling the butter).<br>
<br>
The only SB house with an over-heating problem I visited was one
with a too big window on the west (north hemisphere ;-) and just
one layer of gypsum board over the straw (so no thick plaster to
absorb the excess incoming heat). The choice to apply so little
mass on the SB walls, to keep the costs down, was finaly 'somewhat
regretted' by the owners...<br>
<br>
An other question came up : can we have too much mass?<br>
I'd say : easily!!!!! I'ts exactly what happens in a swimming
pool for instance. The the skinny 4 year olds like it 'not to
cold' when taking their first swimming lessons. The floating
grandma's like it a bit warmer. And so do the babys that come next
with the happy new parents... No problémo... We just put on the
mega heaters and heat up that water during the day. But then come
the waterpolo guys and girls going in for some serious
excersise... and (speaking from experience) I can tell you, water
has a lot of mass and opening all the doors and windows does not
change a thing. It will take a loooooong while 'til that water
cools down... Same goes for a building with a lot of mass. They
take a long time to adapt (to changing needs).<br>
<br>
A third question we could ask : "what would be optimum mass?" was
asked to Earth-shiped Mickeal Reynolds during a conference in
Santa Fé. I understood he answered that an equivalent volume of
mass (earth) connected to the space to be 'conditioned' (+ an
insulation preventing the mass to be to exposed to the rest of the
Universe) is what worked best for them. <br>
But, not everybody likes the idea of pushing a hill against the
shaded side of the house... and, like the point I try to make with
the pool scénario, "constant temperature" does not nescecarily
equal "comfort".<br>
<br>
I don't remember where I read that heat at 'a normal temperature'
will not penetrate more then 7cm/3" of earth (as if I would use
any other plaster ;-) during a day.<br>
Applying the golden 80:20 rule I believe that 5cm/2" is a
practical (not to complicated/expensive) and very effective
tempering diurnal swing.<br>
Having lived 10 years in an earth plastered SB house, with a
masonry heater, in a mild climate close to Bordeaux I also 'feel'
this is true, in all 4 seasons.<br>
If someone would want to use less mass, I'd like them to show me
how they intend to master the flow of calories entering and
leaving the building better than I did; wich, I admit, is very
much possible.<br>
<br>
André - swimming in thoughts- de Bouter<br>
France<br>
<a class="moz-txt-link-abbreviated" href="http://www.lamaisonenpaille.com">www.lamaisonenpaille.com</a><br>
<br>
<br>
<br>
<br>
<br>
<blockquote cite="mid:51881F01.4040105@livingsol.com" type="cite">
<br>
<b>My reference for calculations has been from Dan Chiras's
book, The Solar House. Around pages 100 to 106</b>, Dan offers
information around relationships of types of thermal mass, with
good ratios to use for number crunching. I've been referring to
these ratios for years, and every home that we've designed and
built since then, has worked quite well for our region-specific
designs. And I think you are correct to consider the direct vs.
indirect gain on these wall surface areas. I've used Dan's
ratios, and fudged them a bit, for lit and unlit areas. <br>
Dan refers to ratios of glass-to-mass areas, and specifies using
the ratios of 1:5.5 for sunlit floor areas, and 1:40 for unlit
floor areas. <br>
He specifies 1:8.3 for unlit wall areas, and I've used 1:6 for
sunlit wall areas. That ratio of 1:6 is from my own
imagination, so don't blame Dan for that. Blame my "intuitive
approach" to engineering. After observing the various
passive-solar homes that we've built over the years, the numbers
seem to work. <br>
<br>
</blockquote>
<br>
<div style="">Sometimes single-level homes with a collector slab
will, at night, tend to stratify. The efficiency of heat
transfer can be improved by just a slight level change to drive
the convection loop. Even one step between the bedrooms and
living area is enough to make a significant increase in air
circulation during the night.<br>
<br>
In cooling conditions moisture in the wall will change from gas
to water, releasing considerable heat per unit of water (more
than five times that needed to heat the same quantity of water
from 0 to 100°C), whereas in warming conditions the reverse
occurs. In other words, a breathable earthen wall will have more
temperature moderating effect than one which was sealed against
passage of moisture. The magnitude of this effect would be a
function of several variables, but I can imagine conditions in
which it could be significant. Note that this apart from the
moderating effect on room humidity, which would also have an
effect on perceived temperature.<br>
<br>
Earth ship<br>
</div>
<br>
<br>
<br>
André : <br>
5-7 cm<br>
1st strategy ; regulate the incoming heat (and outgoing heat).<br>
If that is perfect (corresponds with the need/comfort needed, no
mass would be just fine.<br>
If that 'regulation' is 'imperfect' mass allows us to absorb the <br>
<br>
<br>
Stone wall<br>
<br>
Le 13/05/2013 22:53, Derek Stearns Roff a écrit :<br>
</div>
<blockquote cite="mid:2F439374-2438-41E7-8C40-3D8CAE64337E@unm.edu"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
Robert Riversong provided me with the chart below, which combines
all the relevant factors, to come up with a Thermal Mass Index.
Soapstone is the winner by a large margin, so plaster your bales
with soapstone. Saturated sand is next in line, which would make
a great plaster. Marble is good. Clay isn't great on this list,
but it has so many other virtues that it is my first choice.
<div><br>
</div>
<div>Derek</div>
<div><br>
</div>
<div><br>
</div>
<div><img apple-width="yes" apple-height="yes"
id="9bf36b6f-3dcb-4c8b-af36-3787c686ec05"
src="cid:part1.09070304.01050705@lamaisonenpaille.com"
height="504" width="936"><br>
<div><br>
</div>
<div><br>
<div>
<div>On May 13, 2013, at 9:17 AM, Van Krieken wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">Thermal mass, like insulation, its a
general expression, but in fact "thermal mass depends on
the type of material we use.
<div><br>
<div>It is important to know what are the properties and
thermal performances of the materials we want to use,
because each of them have their own thermal
characteristics. Due to their structure and their
mass they manage the heat in different ways:</div>
<div><br>
</div>
<div>a) Statics: conductivity or thermal capacity. How
does the material reacts to a thermal flow,
independently of the reaction time?</div>
<div>b) Dynamics: diffusivity and effusivity. At what
speed the material manages the thermal flow?</div>
<div><br>
</div>
<div>Because the exterior conditions are going to
determine the interior changes, its essential to know
how the materials react. Iron and clay, both thermal
mass, react in a very, very different way.</div>
<div><br>
</div>
<div>1. The thermal conductivity (lambda) gives us the
information concerning the amount of insulation a
material can achieve (air passage of calories).</div>
<div><br>
</div>
<div>2. The thermal capacity, measures its aptitude to
stock the heat. This is the key element to stock the
heat in winter, as well as to absorb the heat in
summer. They are not only heavy materials (like clay
or stone, or cement). Straw, a much more light
material, has also a thermal capacity, and therefore
thermal mass.</div>
<div><br>
</div>
<div>3. The thermal diffusivity <span
style="background-color: rgb(255, 255, 255);
font-family: sans-serif; font-size: 13px;
line-height: 19.1875px; ">is the measure of thermal
inertia and it </span>increases with the
conductivity and decreases with the thermal capacity. <span
style="background-color: rgb(255, 255, 255);
font-family: sans-serif; font-size: 13px;
line-height: 19.1875px; ">In a substance with high
thermal diffusivity, heat moves rapidly through it
(m2/hour). </span></div>
<div><span style="background-color: rgb(255, 255, 255);
font-family: sans-serif; font-size: 13px;
line-height: 19.1875px; "><br>
</span></div>
<div><span style="background-color: rgb(255, 255, 255);
font-family: sans-serif; font-size: 13px;
line-height: 19.1875px; ">4. The thermal effusivity
measures its capacity to exchange its thermal energy
with the environment. The more the effusivity is
high, the more the material absorbs energy without </span><font
face="sans-serif"><span style="line-height:
19.1875px; ">warming up significantly. In
contrary, the more the effusivity is low, the
faster the material warms up.</span></font></div>
<div><font face="sans-serif"><span style="line-height:
19.1875px; "><br>
</span></font></div>
<div><font face="sans-serif"><span style="line-height:
19.1875px; ">Obviously, the thermal mass
importance of a material depends on these
characteristics, but we can help the final result
with some technology. If in a hot climate I do not
have a significant difference of temperature at
night, then I can get 11 or 12º C of fresh air
from the soil (foundations), colling the thermal
mass; or I also can run 19ºC water in radiant
walls made of clay. The same we can do on winter,
stocking the heat on the clay walls.</span></font></div>
<div><br>
</div>
<div><span style="line-height: 19.1875px; font-family:
sans-serif; ">What is the best material for thermal
mass? I do not have a scientific knowledge to tell
it, but I like to think that "clay" -- this
thermally lazy natural and beatifull material -- is
the answer. </span></div>
<div><span style="line-height: 19.1875px; font-family:
sans-serif; "><br>
</span></div>
<div><span style="line-height: 19.1875px; font-family:
sans-serif; ">The simple issue -- my karma its to
arrive allways to a easy conclusion... -- it's how
to use it to keep the heat in cold seasons, and
what to do, to cool it in hot seasons. That's it.</span></div>
<div><font face="sans-serif"><span style="line-height:
19.1875px; "><br>
</span></font></div>
<div><font face="sans-serif"><span style="line-height:
19.1875px; ">All the best</span></font></div>
<div><font face="sans-serif"><span style="line-height:
19.1875px; "><br>
</span></font></div>
<div><font face="sans-serif"><span style="line-height:
19.1875px; ">Jorge Van Krieken</span></font></div>
<div><font face="sans-serif"><span style="line-height:
19.1875px; ">Portugal</span></font></div>
<br class="Apple-interchange-newline">
</div>
</blockquote>
</div>
<br>
<div><span class="Apple-style-span" style="border-collapse:
separate; color: rgb(0, 0, 0); font-family: Helvetica;
font-style: normal; font-variant: normal; font-weight:
normal; letter-spacing: normal; line-height: normal;
orphans: 2; text-align: -webkit-auto; text-indent: 0px;
text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-border-horizontal-spacing: 0px;
-webkit-border-vertical-spacing: 0px;
-webkit-text-decorations-in-effect: none;
-webkit-text-size-adjust: auto; -webkit-text-stroke-width:
0px; font-size: medium; ">Derek Roff<br>
<a moz-do-not-send="true" href="mailto:derek@unm.edu">derek@unm.edu</a><br>
<br>
</span></div>
<br>
</div>
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