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

[Derek Stearns Roff]

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<http://Advisor.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.



Derek Roff
derek at unm.edu<mailto:derek at unm.edu>


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