CONCLUSIONS - SR97_070015

Figure 15. Temperatures above and below horizontal ground insulation

Figure 19. Temperatures 199091 vs. 1992-93

SR97_07
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Figure 17. Yearly temperatures at toe of footing.

Figure 18. Yearly temperatures under horizontal ground

creases. All the measurements were taken 2 ft be-

indices, with the 199192 winter being the most

low grade. Sensor A6 is located under the center

severe and the 199091 and 199293 winters be-

of the addition, B25 at the toe of the footing, A28

ing less severe and approximately equal. This

under the center of the horizontal ground insula-

holds true for the end of the freezing season;

tion, and B4 in the control area. The figure also

however, it becomes evident in the figures that at

shows how the soil temperatures under the foun-

the beginning of the 199091 season the tempera-

dation (i.e., A6 and B25) change very little from

tures are uncharacteristically cold. This was the

winter to winter even though the freezing indices

winter when the addition was still under con-

are quite different.

struction and was heated only occasionally until

the first of December. Figure 19 further illustrates

the importance of using the heat loss from the

CONCLUSIONS

building in an SIF design. Given that the 199091

The shallow insulated foundation used at the

and the 199293 winters had approximately the

addition for the Galena, Alaska, aircraft control

same indices, the temperatures at the sensors are

tower was a cost-effective alternative to a more

clearly lower for the 199091 winter than for the

conventional footing design. Placed at only 20 in.

199293 winter. Assuming the heat was on consis-

below grade where the expected frost depth may

tently from December 1, 1990, it took almost two

reach 12 ft, the shallow foundation was protected

months for the temperatures to return to values

from potential frost damage by extruded poly-

similar to the 199293 winter values.

styrene insulation. Because the site is unique

Figure 20 shows how temperatures decrease as

(i.e., remote), an accurate estimate of economic

the distance from the heated foundation in-

Western Governors University

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