ASHRAE Journal - February 2011 - 63

We present results with the lower soil diffusivity value for this discussion, which is based on the assumption that our slab is significantly above groundwater level and that the warmer slab will move moisture out of the underlying ground. A detailed soil energy transport investigation by Deru and Kirkpatrick1,2 indicates that this property range produces average slab heat fluxes in the 2 to 5 W/m2 range (0.64 to 1.59 Btu/h·ft2). The foundation wall surrounding Equinox House is constructed with insulated concrete forms for an R22 perimeter insulation value. The ICF is made of two 3 in. (76 mm) thick layers of Styrofoam held together with plastic cross pieces. photo 3:	Concrete	poured	in	ICF	founda- photo 4:	Floor	slab	and	exterior	grade	 The plastic cross pieces hold rebar in tion	wall.	The	exterior	ground	is	graded	 are	8	in.	(200	mm)	below	the	top	of	the	 place for the concrete poured between the to	8	in.	(200	mm)	below	the	top	of	the	 ICF	 foundation	 wall	 to	 provide	 barrier	 Styrofoam walls. Photos 1 and 2 (Page 62) ICF	foundation	wall. free	entrances	into	Equinox. show the installation of the ICF foundation block, while Photo 3 shows an exterior view of the ICF after outside Inside concrete was poured. Photo 4 shows the poured concrete floor SIP slab. The slab floor and finished exterior grading are level, resultTreated	 Drywall Sill	Plate ing in barrier free entrances. Figure 1 shows the ICF foundation Concrete	 wall, footer, and concrete slab floor. Frost depth in our region, 8	in. 8	in. Floor on average, is 0.51 m (20 in.), with local building codes requir4	in. ing a footer depth that is below 0.81 m (32 in.). The footer is uninsulated and is treated as having the same properties as the Frost	Depth	 surrounding ground because the thermal diffusivity of concrete 32	in. 40	in. is similar enough to ground (approximately 7 × 10–7 m2/s [75 × 10 –7 ft2/s]). We assumed a depth of 1 m (39 in.) for the depth of the foundation wall below grade, similar to the 1.02 m (40 in.) 10	in. depth of the foundation wall below grade. Most would agree that having a well insulated foundation wall that extends below the frost line is a must in a climate zone such 24	in. as Illinois. Our ground model results support this. Table 1 shows ground model results for a variety of situations. Case 3 is an ICF Figure 1:	ICF	foundation	wall	details	for	Equinox	House.
Case 1 2 3 4 5 6 7 House Description Constant Ambient Temperature ICF, No Slab Insulation Constant Ambient Temperature Perfect Ground Insulation Variable Ambient Temperature ICF, No Slab Insulation Variable Ambient Temperature Perfect Ground Insulation Variable Ambient Temperature 6 in. EPS Variable Ambient Temperature 12 in. EPS Variable Ambient Temperature No ICF or Underslab Ground Energy
(kWh)

Electric
(kWh)

Solar Cost
($)

Solar Array
(ft2)

Floor Insulation Cost ($) 0 – 0 – 5,000 10,000 0

4,200 0 4,050 0 2,140 1,490 4,930

7,310 6,470 6,720 5,840 6,660 6,590 7,090

23,925 21,175 22,000 19,250 21,725 21,450 23,100

468 414 430 376 425 420 452

table 1:	Comparison	of	Equinox	House	annual	energy	predictions,	solar	array	cost,	and	solar	array	size	due	to	foundation	heat	 loss.	Constant	ambient	temperature	assumes	interior	ambient	temperature	is	22°C	(71.6°F)	all	year.	Variable	ambient	temperature	 assumes	monthly	varying	interior	ambient	temperatures	with	NDJFMA=21°C;	M=22°C;	J=24°C;	J,	A=25°C;	S=24°C;	O=22°C.
February 2011 ASHRAE Journal 63



ASHRAE Journal - February 2011

Table of Contents for the Digital Edition of ASHRAE Journal - February 2011

ASHRAE Journal - February 2011
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Thermal Coupling of Cooling and Heating Systems
10 Common Problems in Energy Audits
Hall of Fame Feature: History of the Changing Concepts in Ventilation Requirements
A Guide to Wireless Technologies
Building Sciences
Solar NZEB Project
Emerging Technologies
People
Special Section
InfoCenter
Commissioning
Products
Washington Report
Classified Advertising
Advertisers Index
ASHRAE Journal - February 2011 - ASHRAE Journal - February 2011
ASHRAE Journal - February 2011 - Cover2
ASHRAE Journal - February 2011 - 1
ASHRAE Journal - February 2011 - 2
ASHRAE Journal - February 2011 - Contents
ASHRAE Journal - February 2011 - Commentary
ASHRAE Journal - February 2011 - 5
ASHRAE Journal - February 2011 - Industry News
ASHRAE Journal - February 2011 - 7
ASHRAE Journal - February 2011 - Letters
ASHRAE Journal - February 2011 - 9
ASHRAE Journal - February 2011 - 10
ASHRAE Journal - February 2011 - 11
ASHRAE Journal - February 2011 - 12
ASHRAE Journal - February 2011 - 13
ASHRAE Journal - February 2011 - 14
ASHRAE Journal - February 2011 - 15
ASHRAE Journal - February 2011 - Meetings and Shows
ASHRAE Journal - February 2011 - 17
ASHRAE Journal - February 2011 - Thermal Coupling of Cooling and Heating Systems
ASHRAE Journal - February 2011 - 19
ASHRAE Journal - February 2011 - 20
ASHRAE Journal - February 2011 - 21
ASHRAE Journal - February 2011 - 22
ASHRAE Journal - February 2011 - 23
ASHRAE Journal - February 2011 - 24
ASHRAE Journal - February 2011 - 25
ASHRAE Journal - February 2011 - 10 Common Problems in Energy Audits
ASHRAE Journal - February 2011 - 27
ASHRAE Journal - February 2011 - 28
ASHRAE Journal - February 2011 - 29
ASHRAE Journal - February 2011 - 30
ASHRAE Journal - February 2011 - 31
ASHRAE Journal - February 2011 - 32
ASHRAE Journal - February 2011 - 33
ASHRAE Journal - February 2011 - Hall of Fame Feature: History of the Changing Concepts in Ventilation Requirements
ASHRAE Journal - February 2011 - 35
ASHRAE Journal - February 2011 - 36
ASHRAE Journal - February 2011 - 37
ASHRAE Journal - February 2011 - 38
ASHRAE Journal - February 2011 - 39
ASHRAE Journal - February 2011 - 40
ASHRAE Journal - February 2011 - 41
ASHRAE Journal - February 2011 - 42
ASHRAE Journal - February 2011 - 43
ASHRAE Journal - February 2011 - A Guide to Wireless Technologies
ASHRAE Journal - February 2011 - 45
ASHRAE Journal - February 2011 - 46
ASHRAE Journal - February 2011 - 47
ASHRAE Journal - February 2011 - 48
ASHRAE Journal - February 2011 - 49
ASHRAE Journal - February 2011 - Building Sciences
ASHRAE Journal - February 2011 - 51
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ASHRAE Journal - February 2011 - 53
ASHRAE Journal - February 2011 - 54
ASHRAE Journal - February 2011 - 55
ASHRAE Journal - February 2011 - 56
ASHRAE Journal - February 2011 - 57
ASHRAE Journal - February 2011 - 58
ASHRAE Journal - February 2011 - 59
ASHRAE Journal - February 2011 - 60
ASHRAE Journal - February 2011 - 61
ASHRAE Journal - February 2011 - Solar NZEB Project
ASHRAE Journal - February 2011 - 63
ASHRAE Journal - February 2011 - 64
ASHRAE Journal - February 2011 - 65
ASHRAE Journal - February 2011 - 66
ASHRAE Journal - February 2011 - 67
ASHRAE Journal - February 2011 - 68
ASHRAE Journal - February 2011 - 69
ASHRAE Journal - February 2011 - Emerging Technologies
ASHRAE Journal - February 2011 - 71
ASHRAE Journal - February 2011 - 72
ASHRAE Journal - February 2011 - 73
ASHRAE Journal - February 2011 - 74
ASHRAE Journal - February 2011 - 75
ASHRAE Journal - February 2011 - People
ASHRAE Journal - February 2011 - 77
ASHRAE Journal - February 2011 - InfoCenter
ASHRAE Journal - February 2011 - 79
ASHRAE Journal - February 2011 - 80
ASHRAE Journal - February 2011 - 81
ASHRAE Journal - February 2011 - 82
ASHRAE Journal - February 2011 - 83
ASHRAE Journal - February 2011 - 84
ASHRAE Journal - February 2011 - 85
ASHRAE Journal - February 2011 - Commissioning
ASHRAE Journal - February 2011 - 87
ASHRAE Journal - February 2011 - 88
ASHRAE Journal - February 2011 - 89
ASHRAE Journal - February 2011 - 90
ASHRAE Journal - February 2011 - Products
ASHRAE Journal - February 2011 - Washington Report
ASHRAE Journal - February 2011 - Classified Advertising
ASHRAE Journal - February 2011 - 94
ASHRAE Journal - February 2011 - 95
ASHRAE Journal - February 2011 - Advertisers Index
ASHRAE Journal - February 2011 - Cover3
ASHRAE Journal - February 2011 - Cover4
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