Abstracted from ASHRAE (1989), with permission
Coefficients of transmission U for wood doors (Btu/hr · ft2 · °F)Thickness |
Description |
Winter |
Summer |
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15 mi/h wind |
7.5 mi/h wind |
||||
No storm door |
Wood storm door (50% glass) |
Metal storm door |
No storm door |
||
1 3/8 in |
Hollow-core flush door |
0.47 |
0.30 |
0.32 |
0.45 |
1 3/8 in |
Solid-core flush door |
0.39 |
0.26 |
0.28 |
0.38 |
1 3/4 in |
Solid-core flush door |
0.33 |
0.28 |
0.25 |
0.32 |
1 3/4 in |
Solid-core flush door with single glazing (17% glass) |
0.46 |
0.29 |
0.32 |
0.44 |
1 3/4 in |
Solid-core flush door with insulating glass (17% glass) |
0.37 |
0.25 |
0.27 |
0.36 |
Thickness |
Description |
No storm door |
Metal storm door |
1 3/4 in |
Fiberglass or mineral fiber core with steel stiffeners, no thermal break |
0.60 |
- |
1 3/4 in |
Solid urethane foam core with thermal break |
0.20 |
0.16 |
Single Pane |
Double Pane |
Triple Pane |
Plastic domes |
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No air space |
3/16 inch air space |
1/4 inch air space |
1/2 inch air space |
1/4 inch air space |
1/2 inch air space |
Single wall |
Double wall |
||||||
No low-E coating |
No low-E coating |
No low-E coating |
No low-E coating |
Low-E coating |
Low-E coating |
Low-E coating |
No low-E coating |
No low-E coating |
|||||
No storm sash |
No shade |
Winter |
1.1 |
0.62 |
0.59 |
0.49 |
0.43 |
0.38 |
0.32 |
0.39 |
0.31 |
||
Summer |
1.04 |
0.65 |
0.61 |
0.56 |
0.51 |
0.48 |
0.38 |
0.44 |
0.39 |
||||
Indoor shade |
Winter |
0.83 |
0.52 |
0.48 |
0.42 |
0.38 |
0.36 |
0.3 |
0.31 |
0.26 |
|||
Summer |
0.81 |
0.58 |
0.55 |
0.52 |
0.48 |
0.43 |
0.37 |
0.4 |
0.36 |
||||
Glass outdoor storm sash with 1 inch airspace |
No shade |
Winter |
0.5 |
0.37 |
0.35 |
0.32 |
0.3 |
0.27 |
0.24 |
0.27 |
0.23 |
||
Summer |
0.5 |
0.4 |
0.39 |
0.39 |
0.36 |
0.39 |
0.3 |
0.32 |
0.31 |
||||
Indoor shade |
Winter |
0.44 |
0.29 |
0.28 |
0.25 |
0.24 |
0.22 |
0.2 |
0.22 |
0.19 |
|||
Summer |
0.49 |
0.37 |
0.36 |
0.3 |
0.35 |
0.32 |
0.28 |
0.3 |
0.29 |
||||
Glass indoor storm sash with 1 inch airspace |
No shade |
Winter |
0.5 |
0.37 |
0.35 |
0.31 |
0.29 |
0.27 |
0.25 |
0.27 |
0.23 |
||
Summer |
0.5 |
0.4 |
0.39 |
0.38 |
0.36 |
0.33 |
0.29 |
0.32 |
0.3 |
||||
Indoor shade |
Winter |
0.44 |
0.29 |
0.28 |
0.25 |
0.24 |
0.22 |
0.20 |
0.22 |
0.19 |
|||
Summer |
0.49 |
0.36 |
0.36 |
0.35 |
0.33 |
0.31 |
0.26 |
0.3 |
0.28 |
||||
Acrylic indoor storm sash with 1 inch airspace |
No shade |
Winter |
0.48 |
0.35 |
0.34 |
0.3 |
0.28 |
0.26 |
0.24 |
0.26 |
0.22 |
||
Summer |
0.48 |
0.39 |
0.38 |
0.37 |
0.35 |
0.32 |
0.28 |
0.31 |
0.29 |
||||
Indoor shade |
Winter |
0.42 |
0.28 |
0.27 |
0.24 |
0.23 |
0.22 |
0.2 |
0.22 |
0.18 |
|||
Summer |
0.47 |
0.35 |
0.34 |
0.33 |
0.32 |
0.3 |
0.27 |
0.29 |
0.28 |
||||
Exterior horizontal panels (skylights) |
Winter |
1.23 |
0.7 |
0.65 |
0.59 |
0.48 |
0.52 |
0.56 |
1.15 |
0.7 |
|||
Summer |
0.83 |
0.57 |
0.54 |
0.49 |
0.36 |
0.42 |
0.46 |
0.8 |
0.46 |
Notes: