[Bldg-sim] ASHRAE 90.1 "HC" heat capacity

Andy Hoover andyhoover at thebestconsultant.com
Wed Mar 24 18:34:19 PDT 2010


Hey Seth:

 

Check with the title 24 folk in CA.  I believe they  have/had tables and
http://www.buildex.com/smartwall/tables/tpocmw.html buildex has some tables
showing differing constructions HC.

 

Andy Hoover

Principal

The BEST Consultant, Inc.

Cell: 678-793-1159

Office: 678-200-7648

Fax: 678-827-0574

Email: andyhoover at thebestconsultant.com

Web: www.thebestconsultant.com

 

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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Seth P.
Spangler
Sent: Wednesday, March 24, 2010 9:44 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] ASHRAE 90.1 "HC" heat capacity

 

Hello,

 

ASHRAE defines a mass wall as a wall having a heat capacity (HC) of greater
than 7 BTU/ft2 * F but I have been unable to find this property listed in
tables of building materials. I am trying to calculate the heat capacity of
a CMU wall and would like to confirm that my calculation methodology is
correct.

 

Per ASHRAE 1997 Fundamentals:

.         8" concrete block - two cores filled with concrete (normal weight)
- ~130 lb/ft3

.         Thickness .67 ft

.         Specific Heat ~ 0.22 BTU/lb * F

 

Therefore NC =(130 lb/ft3 )*(.67 ft)*(0.22 BTU/lb * F)

 

NC=19.16

 

Using this methodology even a 4" brick wall has a HC greater than 7 (7.5 to
be exact).

 

Thanks in advance.

 

Seth Spangler, LEEDR AP 

Project Engineer

 

RMF Engineering, Inc 

Ph: (843) 971-9639 ext:1497

Fax: (843) 971-9641 

sspangle at rmf.com

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