Thermal Conductivity

The k-value (thermal conductivity) represents the amount of heat that flows through 1 square foot of a homogeneous material 1 inch thick in 1 hour for each degree of temperature difference between the inside and the outside temperatures.

To illustrate, we shall use an example from the ASHRAE data shown in Tables 3-1 and 3-2. You will note that the k-value for face brick listed in Table 3-1 is 9.0. In other words, 9.0 Btu of heat can pass through 1 ft2 of 1-in-thick face brick each hour. The ther­mal resistance (R-value) of this same 1-in-thick face brick is the reciprocal of its k-value:

11 R =1 = 9 = 011

Conductivity or

Description

Conductance

Resistance (R)

Density

Per Inch

For

(lb per

Thickness

Thickness

Material

Ft3)

00

(c)

L/k

Listed l/C

Air Spaces Position

Heat Flow

Thickness

Horizontal

Up (winter)

3/t-4 in

1.18

0.85

Horizontal

Up (summer)

3/t-4 in

1.28

0.78

Horizontal

Down (winter)

3/t in

0.98

1.02

Horizontal

Down (winter)

IV2 in

0.87

1.15

Horizontal

Down (winter)

4 in

0.81

1.23

Horizontal

Down (winter)

8 in

0.80

1.25

Horizontal

Down (summer)

3/4 in

1.18

0.85

Horizontal

Down (summer)

IV2 in

1.07

0.93

Horizontal

Down (summer)

4 in

1.01

0.99

Sloping, 45°

Up (winter)

3/t-4 in

1.11

0.90

Sloping, 45°

Down (summer)

3/t-4 in

1.12

0.89

Vertical

Horizontal

(winter)

3/t-4 in

1.03

0.97

Vertical

Horizontal

(summer)

3/t-4 in

1.16

0.86

Table 3-1 Conductivities (k), Conductances (Q, and Resistances (R) of

Various Building and Insulating Materials

подпись: various building and insulating materials

Air

Surfaces Still air

15 mph

Wind

7V2 mph

Wind

Building

Board

Boards,

Panels,

Sheathing,

Etc.

Position

Horizontal

Up sloping (45°)

Vertical

Sloping (45°)

Horizontal

Any position—any

Direction (for winter)

Any position—any

Direction (for summer)

Gypsum or plaster board

Gypsum or plaster board

Plywood

Plywood

Plywood

Plywood

Plywood or wood panels

TOC o "1-5" h z 1.63 — 0.61

1.60

Heat Flow

Up —

Up —

Horizontal — Down —

Down —

подпись: heat flow
up -
up -
horizontal — down —
down —
— 0.62

1.46 — 0.68

1.32 — 0.76

1.08 — 0.92

6. — 0.17

4. — 0.25

3.10 — 0.32

2.25 — 0.45

1.25 —

3.20 — 0.31

2.12 — 0.47

1.60 — 0.63

1.7 — 0.94

(continued)

Table 3-1 (continued)

Description

Conductivity or Conductance

Resistance (R)

Material

Density (lb per ft[1])

00

(C)

Per Inch Thickness l/k

For

Thickness Listed l/C

Wood-fiber board,

26

0.42

2.38

Laminated

31

0.50

2.00

Or homogenous

Wood fiber—hardboard

65

1.40

0.72

Type

Wood fiber—hardboard

Vi in

65

5.60

0.18

Type

Wood—fir or pine

25/32 in

1.02

0.98

Sheathing

Wood—fir or pine

L5/s in

0.49

2.03

Building

Vapor—permeable

16.70

0.06

Paper

Felt

Vapor—seal, 2

8.35

0.12

Layers of mopped 15-lb

Felt

Vapor—seal,

Negl

Plastic film

Flooring

Asphalt tile

Vs in

120

24.80

0.04

Materials

Insulating

Materials

Blankets and batts

Carpet and fibrous pad Carpet and rubber pad Ceramic tile Cork tile Cork tile Felt, flooring Floor tile or linoleum—av.

Value Linoleum Plywood subfloor Rubber or plastic tile Terrazzo Wood subfloor Wood, hardwood finish

Cotton fiber

Mineral wool, fibrous form, processed from rock, slag, or glass Wood fiber

Wood fiber, multilayer, stitched expanding

TOC o "1-5" h z 1 in — —

25 0.45

Vs in ———————-

Vs in — 20.00

Vs in 80 —

5/s in————————

Vs in 110———-

1 in — —

25/32 in———- —————-

3/4 in———— —————-

0.8-2.0 0.26

1.5- 4.0 0.27

TOC o "1-5" h z 0.48 — 2.08

0.81 — 1.23

12.50 — 0.08

2.22 —

3.60 — 0.28

16.70 — 0.06

0.05

12.0 — 0.08

1.28 — 0.78

42.40 — 0.02

12.50 — 0.98

1.02 — 0.98

1.47 — 0.68

3.85 —

3.70 —

3.2-3.6 0.25 1.5-2.0 0.27

 

4.00 —

3.70 —

 

(continued)

Table 3-1 (continued)

Description

Conductivity or Conductance

Resistance (R)

Material

Density (lb per ft3)

00

(C)

Per Inch Thickness l/k

For

Thickness Listed IIC

Board

Glass fiber Wood or cane fiber Acoustical tile V2 in Acoustical tile Interior finish (plank, tile, lath)

3/4 in

15.0

9.5

0.84

0.35

0.25

0.56

1.19

2.86

4.00

1.78

Interior finish (plank, tile, lath)

Roof deck slab

V2 in

15.0

0.70

1.43

Approx

IV2 in

0.24

4.17

Approx.

2 in

0.18

5.56

Approx.

Sheathing (impreg. or coated)

3 in

20.0

0.38

0.12

2.63

8.33

Sheathing (impreg. or coated)

V2 in

20.0

0.76

1.32

Sheathing (impreg. or coated)

25/32 in

20.0

0.49

2.06

Cellular glass

Board and slabs

подпись: board and slabsCorkboard (without added binder)

Hog hair (with asphalt binder)

Plastic (foamed)

Wood shredded (cemented in preformed slabs)

Loose fill

подпись: loose fillMacerated paper or pulp products Mineral wood (glass, slag, or rock)

Roof

Insulation

подпись: roof
insulation
Sawdust or shavings Vermiculite (expanded) Wood fiber: redwood, hemlock, or fir All types

V2 in 1 in IV2 in

подпись: v2 in 1 in iv2 inPreformed, for use above deck Approx.

Approx.

Approx.

W

On

6.5- 8.0

8.5

1.62

22.0

2.5- 3.5

2.0- 5.0

8.0- 15.0

7.0

2.0- 3.5

TOC o "1-5" h z 0.27 —

0.33 —

0.29 —

0.55 —

0.28 —

0.30 —

0.45 —

0.48 —

0.30 —

3.70 —

3.0 —

3.45 —

1. 82 —

3.57 —

3.33 —

2.22 —

2.8 —

3.33 —

0.72

0.36

0.24

 

1.39

2.78

4.17

(continued)

 

Description

Conductivity or Conductance

Resistance (R)

Material

Density (lb per ft3)

00

(c)

Per Inch Thickness l/k

For

Thickness Listed IIC

Approx.

2 in

0.19

5.26

Approx.

2V2 in

0.15

6.67

Approx.

3 in

0.12

8.33

Masonry

Cement mortar

116

5.0

0.20

Materials

Concretes

Gypsum-fiber concrete

51

1.66

0.60

87V2% gypsum,

12V2% wood chips

Lightweight aggregates,

120

5.2

0.19

Including expanded

Shale, clay or slate;

100

3.6

0.28

Expanded slags;

Cinders; pumice; perlite;

80

2.5

0.4

Vermiculite;

Also cellular concretes

60

1.7

0.59

40

1.15

0.86

30

0.90

1.11

W

O>

подпись: w
o>

Sand and gravel or stone aggregate (oven dried) Sand and gravel or stone aggregate (not dried) Stucco

Masonry Brick, common Units

Brick, face Clay tile, hollow:

1 cell deep

1 cell deep

2 cells deep 2 cells deep

2 cells deep

3 cells deep

 

3 in

4 in 6 in 8 in 10 in 12 in

 

4 in 8 in 12 in

3 in

4 in 8 in

подпись: 4 in 8 in 12 in
3 in
4 in 8 in
Concrete blocks, three oval core: Sand and gravel aggregate

Cinder aggregate

TOC o "1-5" h z 0.70 — 1.43

9.0

20

140

140

116

120

130

подпись: 20
140
140
116
120
130
— 0.11

12.0 — 0.08

5.0 — 0.20

5.0 0.20

9.0 0.11

1.25

0.90

0.66

0.54

0.45

0.40

 

0.80

1.11

1.52

1.85

2.22

2.50

 

1.40 —

0.90 —

0.78 —

1.16 —

0.90 —

0.58 —

 

0.71

1.11

1.28

0.86

1.11

1.72

(continued)

 

Description

Conductivity or Conductance

Resistance (R)

Material

Density (lb per ft3)

00

(c)

Per Inch For Thickness Thickness l/k Listed IIC

Gypsum partition tile:

3 X 12 X 30-in solid

0.79

— 1.26

3 X 12 X 30-in 4-cell

0.74

— 1.35

3 X 12 X 30-in 3-cell

0.60

— 1.67

3 in

0.79

— 1.27

Lightweight aggregate

4 in

0.67

— 1.50

(expanded shale, clay,

Slate, or slag; pumice)

8 in

0.50

— 2.00

12 in

0.44

— 2.27

Stone, lime, or sand

__

12.50

__

0.08 —

Plastering

Cement plaster, sand

116

5.0

0.20 —

Materials

Aggregate

Sand aggregate

V2 in

10.00

— 0.10

Sand aggregate Gypsum plaster Lightweight aggregate Lightweight aggregate Lightweight aggregate on metal lath Perlite aggregate Sand aggregate Sand aggregate Sand aggregate Sand aggregate on metal lath Sand aggregate on wood lath Vermiculate aggregate Asphalt roll roofing

3/4 in

L/l in Vs in

3/4 in

V2 in Vs in

3/4 in

подпись: 3/4 in
l/l in vs in
3/4 in
v2 in vs in
3/4 in

Roofing

подпись: roofing

3/s in Vi in

подпись: 3/s in vi inAsphalt shingles Built-up roofing Slate

Sheet metal Wood shingles

W

«O

45

45

2.13

TOC o "1-5" h z 45 1.5

105 5.6

105

105 —

45 1.7

70

70

70 3.12

2.67

0.47

0.67 0.18

11. 10 —

9.10

7.70

2.50

0.59

6.50

2.27

3.00

20.0 —

— Negl

1.6 —

0.32

0.39

0.09

0.11

0.13

0.40

0.15

0.44

0.33

0.05

0.94

(continued)

Description

Conductivity or Conductance

Resistance (R)

Density

Per Inch For

(lb per

Thickness Thickness

Material

Ft3)

00

(c)

L/k Listed IIC

Siding

Shingles

Materials

(On flat

Surface)

Wood, 16-in

1.15

— 0.87

7 V2-in exposure

Wood, double, 16-in,

0.84

— 1.19

12-in exposure

Wood, plus insulation

5/l6 in

0.71

— 1.40

Backer board

Siding

Asphalt roll siding

6.50

— 0.15

Asphalt insulating siding

0.69

— 1.45

(Vi-‘m bd.)

Wood, drop, 1 X 8 in

1.27

— 0.79

Wood, bevel, Vi X 8 in,

1.23

— 0.81

Lapped

Wood, bevel, 3/4 X 10 in, lapped

Wood, plywood,

3/s in, lapped Structural glass Woods Maple, oak, and similar hardwoods Fir, pine, and similar softwoods

Courtesy ASHRAE 1960 Guide

TOC o "1-5" h z 45 1.10

32 0.80

1.59 — 0.59

10.0 — 0.10

— 0.91 —

— 1.25 —

Table 3-2 Coefficients of Heat Transmission for Solid Masonry Walls

Resistances Used

Construction Resistance (R)

None

Plaster s/s-in on Plaster on Furring

Metal Lath and 3A-in Plaster on Furring

Gypsum Lath (3/a-in) and ‘A-in Plaster on Furring

Insulation Board Lath (‘A-in) and ‘A-in Plaster on Furring

Wood Lath and ‘A-in Plaster (Sand agg.) 0.40

Resistance

(Sand

°gg-) 0.11

(Lt. Wt.

°gg-)

0.39

(Sand

°gg-)

0.13

(Lt. Wt. No agg.) plas. 0.4 7 0.32

(Sand Lt. wt.

°gg-) °gg-) 0.41 0.64

No (Sand plaster agg.) 1.43 /.52

Material R

U

U

U

U

U

U

U U

U U

U

A

B

C

D

E

F

G H

1

K

Brick (face and common)

(6 in)

0.61

0.68

0.64

0.54

0.39

0.34

0.36

0.35

0.33

0.26

0.25

0.35

1

(8 in)

1.24

0.48

0.45

0.41

0.31

0.28

0.30

0.29

0.27

0.22

0.22

0.29

2

(12 in)

2.04

0.35

0.33

0.30

0.25

0.23

0.24

0.23

0.22

0.19

0.19

0.23

3

(16 in)

2.84

0.27

0.26

0.25

0.21

0.19

0.20

0.20

0.19

0.16

0.16

0.20

4

Brick (common only)

(8 in)

1.60

0.41

0.39

0.35

0.28

0.26

0.27

0.26

0.25

0.21

0.20

0.26

5

(12 in)

2.40

0.31

0.30

0.27

0.23

0.21

0.22

0.22

0.21

0.18

0.17

0.22

6

(16 in)

3.20

0.25

0.24

0.23

0.19

0.18

0.19

0.18

0.18

0.16

0.15

0.18

7

(continued)

Exterior Construction

Interior Finish

No.

None

Plaster s/s-in on Plaster on Furring

Metal Lath and 3A-in Plaster on Furring

Gypsum Lath (3/a-in) and ‘A-in Plaster on Furring

Insulation Board Lath (‘A-in) and ‘A-in Plaster on Furring

Wood Lath and ‘A-in Plaster (Sand agg.) 0.40

Resistance

(Sand

°gg-)

0.11

(Lt. Wt.

°gg-)

0.39

(Sand

°gg-)

0.13

(Lt. Wt. No agg.) plas. 0.4 7 0.32

(Sand Lt. wt.

°gg-) °gg-) 0.41 0.64

No (Sand plaster agg.) 1.43 /.52

Material R

U

U

U

U

U

U

U U

U U

U

A

B

C

D

E

F

G H

1

K

Stone (lime and sand)

(8 in)

0.64

0.67

0.63

0.53

0.39

0.34

0.36

0.35

0.32

0.26

0.25

0.35

8

(12 in)

0.96

0.55

0.52

0.45

0.34

0.31

0.32

0.31

0.29

0.24

0.23

0.31

9

(16 in)

1.28

0.47

0.45

0.40

0.31

0.28

0.29

0.28

0.27

0.22

0.22

0.29

10

(24 in)

1.92

0.36

0.35

0.32

0.26

0.24

0.25

0.24

0.23

0.19

0.19

0.24

11

Hollow clay tile

(8 in)

1.85

0.36

0.36

0.32

0.26

0.24

0.25

0.25

0.23

0.20

0.19

0.25

12

(10 in)

2.22

0.33

0.31

0.29

0.24

0.22

0.23

0.22

0.21

0.18

0.18

0.23

13

(12 in)

2.50

0.30

0.29

0.27

0.22

0.21

0.22

0.21

0.20

0.17

0.17

0.21

14

■u

■b.

подпись: ■u
■b.

Poured concrete 30 lb/ft3

(4 in)

4.44

0.19

0.19

0.18

0.16

(6 in)

6.66

0.13

0.13

0.13

0.12

(Sin)

8.88

0.10

0.10

0.10

0.09

(10 in)

11.10

0.08

0.08

0.08

0.08

80 lb/ft3

(6 in)

2.40

0.31

0.30

0.27

0.23

(8 in)

3.20

0.25

0.24

0.23

0.19

(10 in)

4.00

0.21

0.20

0.19

0.17

(12 in)

4.80

0.18

0.17

0.17

0.15

140 lb/ft3

(6 in)

0.48

0.75

0.69

0.58

0.41

(8 in)

0.64

0.67

0.68

0.53

0.39

(10 in)

0.80

0.61

0.57

0.49

0.36

(12 in)

0.96

0.55

0.52

0.45

0.34

Courtesy ASHRAE 1960 Guide

Vn

подпись: vn

0.15

0.15

0.15

0.11

0.11

0.11

0.09

0.09

0.09

0.07

0.08

0.08

0.21

0.22

0.22

0.18

0.19

0.18

0.16

0.16

0.16

0.14

0.14

0.14

0.36

0.38

0.37

0.34

0.36

0.35

0.32

0.34

0.33

0.31

0.32

0.31

0.14

0.13

0.13

0.11

0.10

0.10

0.09

0.08

0.08

0.07

0.07

0.07

0.21

0.18

0.17

0.18

0.16

0.15

0.15

0.14

0.14

0.14

0.12

0.12

0.34

0.27

0.26

0.32

0.26

0.25

0.31

0.25

0.24

0.29

0.24

0.23

TOC o "1-5" h z 0.15 15

0.11 16

0.09 17

0. 08 18

0. 22 19

0. 18 20

0. 16 21

0. 14 22

0. 37 23

0. 35 24

0. 33 25

0. 31 26

Remember, this is the thermal resistance for a 1-in-thick face brick. Because the masonry wall in Table 3-2 contains a 4-in thickness of face brick, you will have to multiply the R-value (0.11) of the 1-in-thick face brick by 4 (4 in) to obtain the R-value (0.44) for the larger (4-in) section.

Posted in Audel HVAC Fundamentals Volume 1 Heating Systems, Furnaces, and Boilers