[Bldg-sim] Internal Mass Issues with Solar Distribution Model

[Jeff Haberl]

Hello Holly:

FYI...the classic reference on the use of "empirical parameters" is the paper by Janet Manke and Doug Hittle in 1996 about their efforts to calibrate the BLAST program to a building at the Gunnison Airport in Gunnison, Colorado.  In it they show that, when you are calibrating to measured data, the "best fit" values of some of the parameters may have physically unrealistic values...such as the surface area and amount of internal mass in a building...strange stuff...

Jeff

Manke J, Hittle D, Hancock C. Calibrating building energy analysis models
using short term test data. In: Proceedings of the 1996 ASME international
solar engineering conference. San Antonio, TX; 1996. p. 369–78.

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Jeff S. Haberl, Ph.D.,P.E.inactive,FASHRAE,FIBPSA,......jhaberl at tamu.edu
Professor........................................................................Office Ph: 979-845-6507
Department of Architecture............................................Lab Ph:979-845-6065
Energy Systems Laboratory...........................................FAX: 979-862-2457
Texas A&M University...................................................77843-3581
College Station, Texas, USA, 77843.............................http://esl.tamu.edu
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________________________________________
From: Bldg-sim [bldg-sim-bounces at lists.onebuilding.org] on behalf of Samuelson, Holly Wasilowski [hsamuelson at gsd.harvard.edu]
Sent: Friday, January 16, 2015 4:13 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Internal Mass Issues with Solar Distribution Model

Dear Bldg Sim,
I am trying to understand how the internal thermal mass (aka "InternalMass") is being handled in my EnergyPlus models. On page 222 of the EnergyPlus Input-Output Reference it states, "simplifying calculations using internal mass must be used with caution when the "FullInteriorAndExterior" Solar Distribution model is chosen.

Could anyone kindly help me understand what that means?  Does that mean that my internal thermal mass does not "see" the solar radiation potentially hitting it (which might realistically be the case for certain interior elements if they are always in shade)?  However, would you assume that this internal mass is still exposed to the indoor air, and thus could still be absorbing or emitting heat in that way?

Many thanks for any guidance.
Best,
Holly

Holly W. Samuelson, DDes, LEED, AIA
Assistant Professor Harvard Graduate School of Design
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