[BLDG-SIM] Increased R value Credit for Concrete and Themal Massing

[Curtis Pedersen <cpederse@xxxxxxxx>]

Dave:

This concept falls into the "cheater" category.  What happens is that the proponents of heavy construction elements show that the steady periodic behavior of a heavy structure, at some well-selected frequency, is better than the behavior at steady state.  The electrical analogy would be to replace resistance with capacitive impedance.  Of course it depends on the frequency, and it is not resistance, so the steady state (zero frequency) result will be different. 

A reasonable building simulation tool properly accounts for both the capacitance and the resistance of a building element.  The "effective R" is bogus.  

Curtis Pedersen
Professor Emeritus of Mechanical Engineering
University of Illinois



On Tuesday, December 2, 2003, at 11:26 AM, David Stewart wrote:

> Dear Folks
>  
> Has anyone explored the increased R value credits for thermal massing for example Dow T-Mass etc. and can one simply increase the R value to the 'effective R value while changing the mass in DOE.  I would like some more background on this credit with 3rd party validation
>  
> Thanks
>  
> Dave Stewart
>  
> David C. Stewart & Associates Inc.
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