[Bldg-sim] Insulated Concrete Forms (ICF)

[Jon Evans]

Bldg-Sim Group,

Does anyone have energy performance data on Insulated Concrete Forms (ICF), not SIPS, related to commercial buildings, especially in Northern US climates?

Including the effect of reduced infiltration for ICF over standard construction (0.5 ACH vs. 0.25 ACH), I am seeing ~$1,000/yr savings for going to an ~R-27 ICF from an ~R-20 2x6 cavity wall with 1" of rigid.  The building is an ~35,000 SF assisted living facility with a geothermal HVAC system.

Modeling in EQUEST shows minimal annual energy savings and peak load reduction; it seems mainly related to increase R-value and not increased thermal mass.  Off hand, I was under the impression that EQUEST uses ASHRAE transfer functions that account for the thermal mass of the wall if you select "layers input". Could someone confirm/deny this?

Some of my thoughts:
-          I think the daily temperature swings are generally less in a northern climate many days out of the year and the building operates 24/7, therefore the deltaT from inside to outside is low.
-          Likewise, putting insulation between the space and the mass in the wall will slow heat transfer and lower the deltaT as opposed to using passive solar mass/Thomb Walls which the mass is in the space.

Thanks in advance for any comments,


Jon Evans, PE, LEED AP



Sustainable Engineering Group LLC

431 Charmany Drive Suite 102

Madison, WI 53719



Tel: (608) 231 9664 x 13

Fax: (608) 231 9665

E-mail: jevans at sustaineng.com

Web: www.sustaineng.com

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