[GSBN] Fwd: Modeling or measuring mass effect of interior plaster

Mon May 13 16:49:52 UTC 2013

Another undocumented phenomenon would be the "Hypothalamus Effect", the
tendency for people to put on a sweater in response to slow cooling, rather
than rushing to turn on the heat in the face of a more abrupt drop in
temperature. They they go to bed without having called for heat, saving
some Btu's along the way..

On Mon, May 13, 2013 at 6:56 AM, Derek Stearns Roff <derek at unm.edu> wrote:

>  I think the effect is better documented than the cause.  There are a
> number of papers quantifying the positive effect of thermal mass inside the
> insulated building envelope.  Some of them have very sincere-looking
> numbers, especially the ORNL article.  Other articles say that in order to
> be effective, the thermal mass must receive direct insolation, and/or must
> have a diurnal temperature swing above and below the desired indoor
> temperature, leading to thermal lag and the flywheel effect.  I've never
> seen numerical documentation for those assertions.  The ORNL article, which
> is so widely quoted, does not contain the words "sun" or "solar", and makes
> no statement about the range and mid-point of daily temperature swings.
>
>  Some articles state that the thermal mass effect will save energy/money
> based on heating and cooling with fossil fuel or electricity.  This seems
> to be independent of the solar gain question, and leaves open the question
> of daily swingers like John.  Some articles have mentioned that furnaces
> and air conditioners work better when they run on longer cycles, but that
> seems unlikely to explain all of the dynamic thermal performance listed by
> ORNL, nor its variation between the chosen cities.  Bohdan's article also
> documents the dynamic thermal mass effect, without insisting on the cause.
>
>  I'd love to understand this better, and find an article with more
> convincing information on why and how the thermal mass effect functions.
>  So far, it seems like important details concerning the cause are not
> known.
>
>  Derek "just 'cause" Roff
>
>  derek at unm.edu
>
>  On May 12, 2013, at 9:21 PM, John Swearingen wrote:
>
>  Glad there is someone intelligent checking these things, Derek.  The GBA
> article, and I think the research, as well, are centered around looking at
> buildings with heavy mass in exterior walls, particularly in direct contact
> with the sun, so the expected performance of the mass is contingent upon
> the thermal lag of the wall system and the solar glazing.  Our plastered
> straw bale presents a different case.
>
>  I would consider the plaster on bales to be essentially interior walls,
> because they're backed by so much insulation. So then the question becomes,
> what is the effect of high interior mass, the flywheel effect, on energy
> usage. The flywheel is more effective in buildings that experience a
> greater diurnal temperature swing, whether because of direct solar gain or
> conduction through walls and windows.  Few climates don't have temperature
> swings, though, and so, if I understand correctly, that would account for
> the dynamic insulation effect of mass in a variety of climates.
>
>  John "Daily Swing" Swearingen
>
>
>
>
>
> On Sun, May 12, 2013 at 6:58 PM, Derek Stearns Roff <derek at unm.edu> wrote:
>
>> Certainly worth reading, but the primary information source for the Green
>> Building Advisor (GBA) article doesn't fully support the conclusions that
>> the article presents.  GBA references an earlier paper written by
>> researchers at Oak Ridge National Laboratory (ORNL), and most of the other
>> references also use the ORNL data.
>> http://www.ornl.gov/sci/roofs+walls/research/detailed_papers/dyn_perf/index.html
>>   The ORNL data says that even the worst case location, Minneapolis,
>> showed a dynamic insulation effect of almost 1.5 times, such that
>> insulation of R-14 plus internal mass would function like insulation like
>> R-21 in a building lacking significant internal thermal mass.  The best
>> case was location was Phoenix, which, in one of the examples, attained a
>> dynamic thermal performance of 2.58 times.
>>
>>  Both of these locations are the least likely, of the six analyzed
>> locations, to have the diurnal temperature swing above and below the
>> desired indoor temperature, for most of the year.  Denver, which I judge
>> most likely to have those daily temperature swings, was only the third
>> best, and closer in performance to Minneapolis than to Phoenix, with top
>> ratings of 1.88.  In order from best to worst, the six cities analyzed were
>> Phoenix, Atlanta, Denver, Miami, Washington, and Minneapolis.
>>
>>  Unfortunately, the ORNL article doesn't break anything down by season
>> or daily temperature variations, so no data is available to say whether the
>> advantages of interior mass are more pronounced in the summer, winter, or
>> spring/fall.  Several of the articles referenced in this GBA article make
>> statements similar to the one the John quoted for us, but none of them
>> offer any data to support the idea.
>>
>>  Derek
>>
>>
>>  On May 11, 2013, at 9:25 PM, John Swearingen wrote:
>>
>> Martin Holladay, as if he were listening to our discussion, just
>> published an excellent summary "All About Thermal Mass" <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> at
>> Green BuildingAdvisor.com, with references to several studies that have
>> been done.
>>
>>  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.
>>
>>  It's a good read.
>>
>>
>>
>
>
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-- 
John Swearingen
Skillful Means Design & Construction
2550 9th Street   Suite 209A
Berkeley, CA   94710
510.849.1800 phone
510.849.1900 fax

Web Site:  http://www.skillful-means.com
Blog:         https://skillfulmeansdesign.wordpress.com
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