<div dir="ltr">Martin Holladay, as if he were listening to our discussion, just published an excellent summary <a href="http://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-thermal-mass?utm_source=email&utm_medium=eletter&utm_content=gba_eletter&utm_campaign=green-building-advisor-eletter">"All About Thermal Mass" </a> at Green Building Advisor.com, with references to several studies that have been done. <div>
<br></div><div>Most of this has been covered in this discussion. One thing he makes explicit is that mass is most effective in lowering energy usage when the diurnal temperature swing is above and below the indoor temperature (ie: warm days, cool nights). He also points out that mass is most effective in reducing energy usage in cooling environments because the thermal lag will shift air conditioning usage to the cool night hours, when air conditioners are more efficient. </div>
<div><br></div><div style>It's a good read.</div><div><br></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, May 8, 2013 at 12:23 PM, Laura Bartels <span dir="ltr"><<a href="mailto:laura@greenweaver.com" target="_blank">laura@greenweaver.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">Luc, <div><br><div>I'm so grateful to see this. And it brings back some of my 9 years of French study in school. Good to take a stab at reading first without google translate. </div>
<div><br></div><div>But, since I'm still challenged by translating, including technical terms (and google translate seems to be limited here), can you translate inertie quotiedienne cote interieur and how to understand it numerically in non-metric terms? And also how the dephasage or (phase shift or thermal lag) was calculated and what the exterior and interior climate assumptions were? </div>
<div><br></div><div>Perhaps these are explained in text I am not translating correctly. </div><div><br></div><div>Thanks,</div><div>Laura</div><div><br></div><div>
<div><br><div>Begin forwarded message:</div><br><blockquote type="cite"><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><span style="font-family:'Helvetica';font-size:medium;color:rgba(0,0,0,1)"><b>From: </b></span><span style="font-family:'Helvetica';font-size:medium">Laura Bartels <<a href="mailto:laura@greenweaver.com" target="_blank">laura@greenweaver.com</a>><br>
</span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><span style="font-family:'Helvetica';font-size:medium;color:rgba(0,0,0,1)"><b>Date: </b></span><span style="font-family:'Helvetica';font-size:medium">May 8, 2013 10:02:00 AM MDT<br>
</span></div><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><span style="font-family:'Helvetica';font-size:medium;color:rgba(0,0,0,1)"><b>To: </b></span><span style="font-family:'Helvetica';font-size:medium">Global Straw Building Network <<a href="mailto:GSBN@sustainablesources.com" target="_blank">GSBN@sustainablesources.com</a>><br>
</span></div><div class="im"><div style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0px"><span style="font-family:'Helvetica';font-size:medium;color:rgba(0,0,0,1)"><b>Subject: </b></span><span style="font-family:'Helvetica';font-size:medium"><b>Re: [GSBN] Modeling or measuring mass effect of interior plaster</b><br>
</span></div><br></div><div style="word-wrap:break-word">Luc, <div>I'm so grateful to see this. And it brings back <br><div>
<span style="border-collapse:separate;font-family:'Times New Roman';font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;font-size:medium"><span style="border-collapse:separate;font-variant:normal;letter-spacing:normal;line-height:normal;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="border-collapse:separate;font-variant:normal;letter-spacing:normal;line-height:normal;text-align:-webkit-auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div>
<span style="border-collapse:separate;font-variant:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><span style="border-collapse:separate;font-variant:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div class="MsoNormal">
<font color="#4C721D" face="'Times New Roman'"><b><i><div class="MsoNormal"><font color="#4C721D" face="'Times New Roman'"><b><i><span style="border-collapse:separate;font-variant:normal;letter-spacing:normal;line-height:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div class="MsoNormal">
<font color="#4C721D" face="'Times New Roman'"><b><i><font><font color="#4C721D" face="'Times New Roman'"><b><i><div class="im"><div style="font-style:normal;font-size:12px;font-family:Helvetica;font-weight:normal">
<div class="MsoNormal"><span style="color:rgb(76,114,29);font-family:'Times New Roman';font-size:16px;font-style:italic;font-weight:bold">Laura Bartels</span></div><div class="MsoNormal"><font color="#4C721D" face="'Times New Roman'" size="4"><span style="font-size:16px"><b><i>GreenWeaver Inc.</i></b></span></font></div>
<span style="font-size:12pt;font-family:'Times New Roman';color:rgb(76,114,29)"><b><i>520 S. Third St., Suite 5 </i></b></span></div></div><div style="font-style:normal;font-size:12px;font-family:Helvetica;font-weight:normal">
<span style="font-size:12pt;font-family:'Times New Roman';color:rgb(76,114,29)"><b><i>Carbondale, CO 81623<br><a href="tel:970-379-6779" value="+19703796779" target="_blank">970-379-6779</a><br><a href="http://www.greenweaverinc.com" target="_blank">www.greenweaverinc.com</a></i></b></span></div>
<div><span style="font-size:16px"><br></span></div></i></b></font></font></i></b></font></div></span></i></b></font></div></i></b></font></div></span></span></div></span><br><img height="99" width="201" src="cid:BEE497CD-A097-4C96-B8DC-20DC694F15B3@gateway.2wire.net">
</span></span></div>
<br><div><div class="im"><div>On May 8, 2013, at 5:43 AM, Luc Floissac wrote:</div><br></div><blockquote type="cite">
<div text="#000000" bgcolor="#FFFFFF"><div class="im">
<div>Hi,<br>
I've studied several kinds of wall in my book "La construction en
paille" (in french...)<br>
<a href="http://www.amazon.com/construction-paille-fondamentaux-Techniques-r%C3%A9alisations/dp/2360980815" target="_blank">http://www.amazon.com/construction-paille-fondamentaux-Techniques-r%C3%A9alisations/dp/2360980815</a><br>
<br>
You can find here attached an extract of the book<br>
I've and measured the mass effect on the internal side ("inertie
quotidienne du côté intérieur" in french) in respect with ISO
13786 document (see p. 36).<br>
The nature and thickness of the outside coverage of a SB wall have
a very little influence to the inside <font face="Arial"><span style="font-size:9pt">thermal performance.</span></font><br>
<br>
I've also realized some mass effect statistics on the 40 SB
building studied (see p. 37). You can see that many SB buidings
have strong or middle internal mass.<br>
<br>
Regards.<br>
Luc<br>
<pre cols="72">--
Luc Floissac - Conseiller environnemental
Eco-Etudes à "En Pommel" 31570 LANTA
tél. 09 77 36 92 04
<a href="http://www.eco-etudes.com/" target="_blank">www.eco-etudes.com</a>
<a href="mailto:luc.floissac@wanadoo.fr" target="_blank">luc.floissac@wanadoo.fr</a></pre>
<br>
<br>
<br>
Le 08/05/2013 12:29, martin hammer a écrit :<br>
</div>
</div><blockquote type="cite">
<font face="Arial"><span style="font-size:9pt">Great discussion on
this subject. <div><div class="h5"><br>
<br>
I often characterize plastered straw bale walls as “a perfect
balance of mass and insulation”. A generalization, to be
sure, but not far off, for almost any climatic condition. I
also often refer to them as “natural SIPs”. Structural
Insulated Panels, are usually thought of as having an
insulating polymer foam core between layers of plywood or OSB,
but can also include a similar core between layers of cement
plaster (applied in situ). These are sometimes called
“composite panel building systems” or “structural insulated
reinforced concrete panels”. Structurally, plastered SB walls
(can) function like any of the SIPs, but thermally they
perform only like SIPs with the cement plaster skins. (Though
I suppose gypsum board is sometimes applied to the interior
and cement plaster to the exterior of OSB SIPs, which
thermally gets them closer to SB walls.) <br>
<br>
The systems with cement plaster skins usually use a welded
steel wire space frame that ties the skins together through
the insulating foam core. If you squint hard and ignore
petro-chemical insulations and the Portland cement based
plaster (I know that’s impossible), then in terms of
structural and thermal performance its a great system. This
might be like saying “except for the fact that it’s terrible,
it’s great!”, but there’s a valid point in there somewhere.
And one could presumably use lime plaster or soil-cement (or
even clay plaster?) with one of these foam-wire-core systems
(anyone done that?) that would significantly reduce the
environmental downside but maintain the thermal performance
and structural capacity (with careful consideration of the
weaker plasters for the particular application). <br>
<br>
Of course instead of messing with any of that one could just
build SB walls. I’m just making a comparison to “similar”
industrialized systems, that to be fair, have certain
advantages. One advantage is SIPs (with wood panel or
reinforced cement plaster skins) can be used structurally for
floor and roof elements and plastered SB cannot
(notwithstanding SB vaults).<br>
<br>
One observation on the very good article Bohdan shared, is
that the mid-mass building gets you far in terms of thermal
performance (compared to the low-mass building), whereas the
high-mass building then demonstrates a more modest
improvement. Like anything else, the first steps in the right
direction have the largest payoff, with still-valuable but
diminishing return after that.<br>
<br>
One other thought is that the mass on the interior of a
plastered SB wall is more important than the mass on the
exterior in terms of thermal performance. I wonder if anyone
has therefore used a thicker interior plaster than exterior.<br>
<br>
Martin<br>
<br>
<br>
On 5/7/13 5:23 PM, "Derek Roff" <<a>derek@unm.edu</a>> wrote:<br>
<br>
</div></div></span></font><div><div class="h5">
<blockquote><font face="Arial"><span style="font-size:9pt">Thanks
for posting the article on thermal mass, Bohdan. I found it
very interesting. Based on the data it contains, I have a
few comments relevant to Laura's situation. <br>
<br>
As John mentioned, the article emphasizes that it is
addressing thermal mass with direct solar exposure/gain.
However, I didn't see anything quantifying what amount of
time the sun needs to shine on each bit of thermal mass
floor and wall each day, in order to attain the listed
results. As the sun moves across the sky, some parts of the
floor and walls will receive direct sunlight for only a few
minutes, while other locations will be in the sun for
several hours per day. The amount of furniture, area rugs,
and wall decorations will also affect how much sun shines on
thermal mass. I'm thinking that as the amount of time in
the sun decreases, the needed surface area of the thermal
mass needs to increase, to get the same thermal mass effect.
The total mass of the thermal mass might need to increase a
bit, too. <br>
<br>
At 6000 sq ft/560m3, Laŭra's project will likely have a
higher floor area to wall area ratio than smaller houses.
By itself, this might decrease the importance of the
thermal mass in the walls. However, depending on the number
of stories and the floor plan, a large project might have a
smaller percentage of floor and wall area accessible to
direct sun. That would increase the importance of
maximizing the surface area of the thermal mass. <br>
<br>
Laura didn't say where this project will be built, but I'm
guessing it might have a climate closer to the "cold
European climate" listed in the article, rather than to the
alternative Melbourne figures. The article quotes Vale and
Vale as suggesting 1,200kg of thermal mass for each square
meter of floor area. It's worth noting that all this
thermal mass could not be in the floor. If it were, the
thermal mass floor would need to be about .5m/20" thick.
Not only is that absurd from a construction perspective,
but much of the mass in a slab that thick would not respond
to daily temperature variation. My reading is that walls
have to be involved in the thermal mass equation, to get the
results described. <br>
<br>
At the top right of page 7, the article says that
temperature modeling for the three reference building
variations (low-mass, medium-mass, and high-mass) are
predicted to have similar maximum temperatures. However,
the numbers in the chart paint a different picture, as I see
it. Table 3 shows the maximum temperature at the hottest
part of the summer as 32 degrees C/90 degrees F for the low
mass house, contrasted with 25 C/77 F for the high-mass
house. To me, that's the difference between the average
American demanding air conditioning (or feeling that they
are suffering), versus a temperature that many would find
acceptable. 23 C/77 F is pretty comfortable, when the
radiant surfaces (ceiling, walls and floors) are at a
similar temperature or lower, as they would be in a
well-insulated home. That temperature can feel
uncomfortable, if the radiant surfaces have heated up to 30
C/86 F or more. <br>
<br>
Table 3 also shows surprising figures for the morning lows
in the hottest month. The low-mass building is predicted to
be at 16 C/61 F on a summer morning. Some residents would
be turning on the heat in the morning, and the air
conditioning in the afternoon. The high-mass building will
get down to a comfortable 20 C/68 F on the same summer
morning. To the extent that covering the walls with barn
wood will diminish the effective thermal mass, as Laura
describes, it could have a significant impact on comfort in
the summer. The winter figures indicate substantially
greater differences between high-mass and low-mass
temperature variations. I also conclude that Hobart has a
pretty pleasant temperature range. <br>
<br>
I agree with David, that uninsulated thermal mass can easily
be a liability. I'm not sure the same is true for
well-insulated thermal mass. A large amount of thermal mass
combined with a well-insulated building envelope will result
in small daily temperature variations. At some point,
adding more thermal mass will have little effect, because of
the low temperature swing and the resulting low delta T
across the thermal mass. After this point, adding more
thermal mass wouldn't help much, but I'm not seeing how it
would have a negative effect, either. Unless the residents
found consistent temperatures monotonous. <br>
<br>
Derek<br>
<br>
On May 6, 2013, at 7:05 PM, Bohdan Dorniak wrote:<br>
<br>
</span></font>
<blockquote><font size="5"><font face="Calibri, Verdana,
Helvetica, Arial"><span style="font-size:11pt">Hi All<br>
This is a note that has been published by the Australian
Institute of Architects regarding Thermal Mass.<br>
I thought that you may find this interesting? Any
comments John?? Laura??<br>
Regards<br>
Bohdan Dorniak<br>
<br>
</span></font></font><font size="4"><font face="Tahoma,
Verdana, Helvetica, Arial"><span style="font-size:10pt"><b>From:</b>
<font color="#0000FF"><a>GSBN-bounces@sustainablesources.com</a></font>
[<a href="mailto:GSBN-bounces@sustainablesources.com" target="_blank">mailto:GSBN-bounces@sustainablesources.com</a>]
<b>On Behalf Of </b>John Swearingen<br>
<b>Sent:</b> Tuesday, 7 May 2013 9:38 AM<br>
<b>To:</b> Global Straw Building Network<br>
<b>Subject:</b> Re: [GSBN] Modeling or measuring mass
effect of interior plaster<br>
</span></font></font><font size="5"><font face="Times New
Roman"><span style="font-size:12pt"> <br>
Laura,<br>
<br>
Modeling thermal mass is generally difficult because of
the large variable conditions of heat transfer related
to air circulation. We've done this in Energy-10 with
some success, and usually our projections have come out
on the conservative side--the temperature swings have
been less than we calculated. <br>
<br>
The other very large variable is climate--temperatures
and sunshine at different times of the year. Everyone I
know who does this successfully had dialed it in from
years of experience in one particular climate, with
which they are familiar.<br>
<br>
As to whether the walls make a difference, the short
answer is, I think it makes a big difference, and that
many of the lauded characteristics of thermal comfort in
straw bale buildings may have as much to do with the
thermal mass on the walls as with the insulation.
Modulated temperature swings can influence occupant
behavior positively, reducing reliance on mechanical
systems, over and above straight Btu calculations.<br>
<br>
The ultimate efficiency of thermal mass is tied to the
heat-transfer mechanism for exchanging heat between the
mass and the rest of the building (air). A floor slab
is thick and of limited surface area; bale walls are
thin with a much larger surface area. So floor slabs are
longer term storage, and walls function very
effectively to modulate temperature swings on a short
term (diurnal) cycle which can reduce loads on
mechanical systems and increase comfort in passive
buildings. I don't think there is too much danger of
over-massing, and haven't seen it in our buildings,
because the relatively thin mass of the walls, backed by
insulation and actively transferring heat, stays close
to room temperature and so isn't felt as too cold or
hot.<br>
<br>
Temperature modulation can result in significant changes
in how mechanical heating and cooling are used by the
occupants: if the building is slow to cool off at night,
for instance, the occupants don't call for heat early in
the evening. The key here is responsiveness, which is
related to surface area. Mass walls also help to
distribute Btu's somewhat between warmer and cooler
areas of the building: cooler walls will absorb heat
more readily than warm walls, so they are somewhat of a
magnet for warm air when located in cooler areas of the
building. <br>
<br>
Well, hope this helps!<br>
<br>
John.<br>
<br>
<br>
<br>
</span></font><span style="font-size:12pt"><font face="Helvetica, Verdana, Arial"><br>
</font><font face="Times New Roman">On Mon, May 6, 2013 at
12:39 PM, Laura Bartels <<font color="#0000FF"><a>laura@greenweaver.com</a></font>>
wrote:<br>
Hello All,<br>
<br>
I'm writing to ask if anyone has had experience with
modeling or measuring the mass effect of interior
plaster of bale walls versus other interior finishes.
This has come up on a straw bale project in design phase
I've involved in which has a net zero energy goal. The
project is large, about 6000 sf. The owners are
interested in barnwood interior wall surfaces (over
plaster) on all or some walls. With the net zero goal,
the question is what we might lose in having wood rather
than exposed plaster. There will be adobe floors which
will already provide direct and indirect gain mass. <br>
<br>
Anyone tackled this topic or have a guess about how to
look at this? Our team has talked about estimating
direct vs. indirect gain wall surfaces through sun
studies in ArchiCAD as a starting point. <br>
<br>
Looking forward to hearing any thoughts on this.<br>
<br>
Laura<br>
<br>
<br>
<b><i>Laura Bartels<br>
GreenWeaver Inc.<br>
520 S. Third St., Suite 5 <br>
Carbondale, CO 81623<br>
<font color="#0000FF"><a href="tel:970-379-6779" value="+19703796779" target="_blank">970-379-6779</a>
<tel:<a href="tel:970-379-6779" value="+19703796779" target="_blank">970-379-6779</a>> <br>
<a href="http://www.greenweaverinc.com/" target="_blank">www.greenweaverinc.com</a> <<a href="http://www.greenweaverinc.com/" target="_blank">http://www.greenweaverinc.com</a>>
<br>
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</span></font></i></b><font size="6"><span style="font-size:13pt"><br>
<image001.jpg><br>
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</blockquote>
<br>
<fieldset></fieldset>
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</div></div></blockquote>
<br>
<br>
<pre cols="72"></pre>
</div>
<span><p 035-038 - Inertie Extrait de La construction en paille - Luc Floissac - Editions Terre vivante.pdf></span>_______________________________________________<div class="im"><br>GSBN mailing list<br><a href="mailto:GSBN@sustainablesources.com" target="_blank">GSBN@sustainablesources.com</a><br>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><font face="'trebuchet ms', sans-serif"><span style="font-size:x-small"><font color="#666666">John Swearingen<br>Skillful Means Design & Construction<br>
2550 9th Street Suite 209A<br>Berkeley, CA 94710<br>510.849.1800 phone<br>510.849.1900 fax<br><br>Web Site: <a href="http://www.skillful-means.com" target="_blank">http://www.skillful-means.com</a><br>Blog: <a href="https://skillfulmeansdesign.wordpress.com" target="_blank">https://skillfulmeansdesign.wordpress.com</a></font></span></font>
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