INSTRUMENTATION - SR97

Although the floor's surface temperature would

The temperature sensors used at the addition

be slightly lower at the outer edge, the design

were type-T, copper-constantan thermocouples.

strategy was to use the additional heat lost to the

The sensor wires were crimped together at the end

subgrade to keep the footing frost-free.

and coated with an epoxy. A cap was then heat-

Also note in Figure 4b the non-frost-susceptible

shrunk around the sensor to make it completely

(NFS) drainage layer, perforated drain tile, and 8-

waterproof. The thermocouples were connected

mil plastic film. These are specified to minimize

to low-resistance switches located inside the addi-

any moisture from coming in contact with the

tion and read using a digital thermometer. The

insulation or foundation.

overall accuracy with the type-T sensors is

approximately 0.8F.

The temperature strings were read once a week

INSTRUMENTATION

by the weather technicians. Because it is a first-

Temperature sensors were installed along the

order weather station, meteorological data were

east side of the addition because it was thought

available.

that the coldest ground temperatures would occur

there. The building profile is narrow along this

FOUNDATION CONSTRUCTION

side and thus the heat loss from the building to the

ground is minimal. Also, the east side of the addi-

Construction on the foundation began in June

tion is kept free of snow for vehicle parking.

1990 and the project was completed in December

During the spring of 1990, 64 temperature sen-

1990. No precise length of time can be attributed

sors were installed to get a temperature profile of

to the foundation construction phase because the

the SIF. After a winter's worth of data, it was obvi-

crew was continually pulled from the site to work

ous that additional sensors would be needed be-

on other projects. However, conversations with

cause the frost line was penetrating deeper than

the site foreman revealed that a substantial

anticipated and more detailed temperature infor-

amount of time was saved: he estimated the SIF

mation was needed under the ground insulation.

took 12 weeks to complete whereas a conven-

Sixteen additional sensors were installed during

tional foundation would have taken 34 weeks.

the summer of 1991. The location of all sensors can

Construction of the SIF is similar to a conven-

be seen in Figure 5.

tional foundation and is very straightforward.

Because of scheduling conflicts, temperature

Figure 6 depicts the excavation along the east side

sensors were not installed above the slab insula-

of the addition. The laborers are leveling the bot-

tion or within the floor itself. This would have

tom of the excavation; the footings will be placed

been useful in determining the comfort level of the

at this elevation. In Figure 7 the footing and stem

floor. Comments on comfort were verbally provid-

wall have been poured and the excavation has

been backfilled to the top of the footing. (The man

ed by the weather technicians using the facility.

Distance (ft)

0

14

16

18

20

22

24

2

4

6

8

10

12

A40

0

A3

A1

A4

B1

A33 B36

A32

A31

B13

A2

A5

B2

B35

A27

A23

B14

2

A6

B3

A28

B25

A24

B15

A7

B4

A29

B26

A25

A3

B16

A8

B5

B27

A30

A26

A3

B17

A9

B6

A16

B28

A21

B18

A10

4

B7

A17

B29

A13

B19

A3

B8

A18

A14

B20

B9

A11

B30

A19

A15

B21

B22

A3

6

B10

A12

A20

B31

A22

B23

B24

A39

B11

B32

A38

8

B12

B38

B34

10

B40

Concrete

B37

B33

12

Insulation

B39

14

Figure 5. Location of temperature sensors.

5