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 |
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 — |
— 0.62
1.46 — 0.68
1.32 — 0.76
1.08 — 0.92
6. — 0.17
4. — 0.25
3.10 — 0.32
1.25 —
3.20 — 0.31
1.60 — 0.63
1.7 — 0.94
(continued)
Table 3-1 (continued)
|
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
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 —
|
|
(continued)
Table 3-1 (continued)
|
Cellular glass
Board and slabs |
Corkboard (without added binder)
Hog hair (with asphalt binder)
Plastic (foamed)
Wood shredded (cemented in preformed slabs)
Loose fill |
Macerated paper or pulp products Mineral wood (glass, slag, or rock)
Roof Insulation |
Sawdust or shavings Vermiculite (expanded) Wood fiber: redwood, hemlock, or fir All types
V2 in 1 in IV2 in |
Preformed, for use above deck Approx.
Approx.
Approx.
W
On
6.5- 8.0
8.5
1.62
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 —
2.8 —
3.33 —
|
|
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> |
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:
|
|
||
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 |
— 0.11
12.0 — 0.08
5.0 — 0.20
5.0 0.20
9.0 0.11
|
|
|
|
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 |
Roofing |
3/s in Vi in |
Asphalt 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. |
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 |
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