ASHRAE Journal - April 2010 - 57

insulated basement. Figure 6 is the ground temperature profile for a heated and insulated basement. The ground clearly gets colder with the addition of basement insulation. But the key point to remember is that the gradient does not change when the basement is insulated. The heat flow is greatly reduced, but the direction is still the same. But what if I do not want to heat the basement? Easy, reduce the heat loss of the ground to the atmosphere. Add a skirt of insulation around the perimeter (Figure 7). How wide should the skirt be? What should its thermal resistance be? Questions, questions, questions. The answer is, no surprise, based on experience. The skirt width should be equal to the average frost depth, and the R-value should be based on the freezing degree days. These are typically specified in codes governing shallow frost protected foundations. When in doubt, pick R-10 or greater. But what if I don’t want to excavate all of that dirt around the perimeter to install a wide insulation skirt? Are there other options? Of course there are. If you do not have frost susceptible soils, and if you do not have saturated soil, you do not have a problem. Get rid of the frost susceptible soils or get rid of the water, or even better, get rid of both (Figure 8). So, why in cases where we have unheated foundations and frost susceptible soils we still don’t have many problems? Well, mostly luck and some unexpected and underappreci-

21.4°C 16.3°C 11.1°C 6.0°C 0.8°C –4.3°C –9.4°C –14.6°C –19.7°C

Figure 3 (left): Infrared THERM Simulation of an Uninsulated Basement Wall. Insulation or no insulation, the thermal gradient is away from the foundation wall. Figure 4 (right): Infrared THERM Simulation of an Insulated Basement Wall. Insulation or no insulation, the thermal gradient is away from the foundation wall.

ated drainage. With many rubble foundations, we dodge the adfreezing bullet and lateral frost heave forces because the rubble foundation wall is a pretty good drainage medium (Figure 9).

Snow Cover

Uninsulated and Heated

Snow Cover

Insulated and Heated

Snow Cover

Insulated and Heated; Frost Heave Protected

Figure 5 (left): Isotherms in the Ground Adjacent Foundations. The ground temperature profile for a heated and uninsulated basement (adapted from Penner, E., K.N. Burn. 1970. “Adfreezing and frost heaving of foundations.” Canadian Building Digest). Figure 6 (right): Isotherms in the Ground Adjacent Foundations: The ground temperature profile for a heated and insulated basement. The ground clearly gets colder with the addition of basement insulation. But the key point to remember is that the gradient does not change when the basement is heated. The heat flow is greatly reduced, but the direction is still the same.

Figure 7: Insulation “Skirt.” The skirt width should be equal to the average frost depth and the R-value should be based on the freezing degree days. These are typically specified in codes governing shallow frost protected foundations. When in doubt, pick R-10 or greater. Or go to the source:, Robinsky, I., K.E. Bespflug. 1973. “Design of insulated foundations.” Journal of the Soil Mechanics and Foundations Division 99(9):649 – 667. ASHRAE	Journal	 57

April	2010	



ASHRAE Journal - April 2010

Table of Contents for the Digital Edition of ASHRAE Journal - April 2010

ASHRAE Journal - April 2010
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
The Science of Evaporation is Key to Defense in Murder Trial
Selecting DOAS Equipment with Reserve Capacity
Technology Award Case Studies: Greening Hospitals
Technology Award Case Studies: Sustainable Remedy for Hospital
Building Sciences
Emerging Technologies
Technical Topics: Selecting Efficient Fans
Technical Topics: Dual-Capacity Heat Pumps
IAQ Applications
International Column
Classified Advertising
Advertisers Index
ASHRAE Journal - April 2010 - Intro
ASHRAE Journal - April 2010 - ASHRAE Journal - April 2010
ASHRAE Journal - April 2010 - Cover2
ASHRAE Journal - April 2010 - 1
ASHRAE Journal - April 2010 - 2
ASHRAE Journal - April 2010 - Contents
ASHRAE Journal - April 2010 - Commentary
ASHRAE Journal - April 2010 - 5
ASHRAE Journal - April 2010 - Industry News
ASHRAE Journal - April 2010 - 7
ASHRAE Journal - April 2010 - 8
ASHRAE Journal - April 2010 - 9
ASHRAE Journal - April 2010 - 10
ASHRAE Journal - April 2010 - 11
ASHRAE Journal - April 2010 - 12
ASHRAE Journal - April 2010 - 13
ASHRAE Journal - April 2010 - 14
ASHRAE Journal - April 2010 - 15
ASHRAE Journal - April 2010 - 16
ASHRAE Journal - April 2010 - 17
ASHRAE Journal - April 2010 - Letters
ASHRAE Journal - April 2010 - 19
ASHRAE Journal - April 2010 - Meetings and Shows
ASHRAE Journal - April 2010 - 21
ASHRAE Journal - April 2010 - The Science of Evaporation is Key to Defense in Murder Trial
ASHRAE Journal - April 2010 - 23
ASHRAE Journal - April 2010 - 24
ASHRAE Journal - April 2010 - 25
ASHRAE Journal - April 2010 - 26
ASHRAE Journal - April 2010 - 27
ASHRAE Journal - April 2010 - 28
ASHRAE Journal - April 2010 - 29
ASHRAE Journal - April 2010 - Selecting DOAS Equipment with Reserve Capacity
ASHRAE Journal - April 2010 - 31
ASHRAE Journal - April 2010 - 32
ASHRAE Journal - April 2010 - BRC1
ASHRAE Journal - April 2010 - BRC2
ASHRAE Journal - April 2010 - 33
ASHRAE Journal - April 2010 - 34
ASHRAE Journal - April 2010 - 35
ASHRAE Journal - April 2010 - 36
ASHRAE Journal - April 2010 - 37
ASHRAE Journal - April 2010 - 38
ASHRAE Journal - April 2010 - 39
ASHRAE Journal - April 2010 - 40
ASHRAE Journal - April 2010 - 41
ASHRAE Journal - April 2010 - Technology Award Case Studies: Greening Hospitals
ASHRAE Journal - April 2010 - 43
ASHRAE Journal - April 2010 - 44
ASHRAE Journal - April 2010 - 45
ASHRAE Journal - April 2010 - 46
ASHRAE Journal - April 2010 - 47
ASHRAE Journal - April 2010 - 48
ASHRAE Journal - April 2010 - 49
ASHRAE Journal - April 2010 - Technology Award Case Studies: Sustainable Remedy for Hospital
ASHRAE Journal - April 2010 - 51
ASHRAE Journal - April 2010 - 52
ASHRAE Journal - April 2010 - 53
ASHRAE Journal - April 2010 - Building Sciences
ASHRAE Journal - April 2010 - 55
ASHRAE Journal - April 2010 - 56
ASHRAE Journal - April 2010 - AP1
ASHRAE Journal - April 2010 - AP2
ASHRAE Journal - April 2010 - AP3
ASHRAE Journal - April 2010 - AP4
ASHRAE Journal - April 2010 - 57
ASHRAE Journal - April 2010 - 58
ASHRAE Journal - April 2010 - 59
ASHRAE Journal - April 2010 - Emerging Technologies
ASHRAE Journal - April 2010 - 61
ASHRAE Journal - April 2010 - 62
ASHRAE Journal - April 2010 - 63
ASHRAE Journal - April 2010 - Technical Topics: Selecting Efficient Fans
ASHRAE Journal - April 2010 - 65
ASHRAE Journal - April 2010 - Technical Topics: Dual-Capacity Heat Pumps
ASHRAE Journal - April 2010 - 67
ASHRAE Journal - April 2010 - 68
ASHRAE Journal - April 2010 - 69
ASHRAE Journal - April 2010 - IAQ Applications
ASHRAE Journal - April 2010 - 71
ASHRAE Journal - April 2010 - 72
ASHRAE Journal - April 2010 - 73
ASHRAE Journal - April 2010 - International Column
ASHRAE Journal - April 2010 - 75
ASHRAE Journal - April 2010 - 76
ASHRAE Journal - April 2010 - 77
ASHRAE Journal - April 2010 - 78
ASHRAE Journal - April 2010 - 79
ASHRAE Journal - April 2010 - 80
ASHRAE Journal - April 2010 - 81
ASHRAE Journal - April 2010 - 82
ASHRAE Journal - April 2010 - 83
ASHRAE Journal - April 2010 - 84
ASHRAE Journal - April 2010 - 85
ASHRAE Journal - April 2010 - Classified Advertising
ASHRAE Journal - April 2010 - 87
ASHRAE Journal - April 2010 - Advertisers Index
ASHRAE Journal - April 2010 - Cover3
ASHRAE Journal - April 2010 - Cover4
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