Envelope Typical Values (US)

Glazing U-Factor (BTU/h-ft2 -°F)

Description Lower Upper

Single Glazing

- including frame and sash

 0.65 1.1

Standard Double Glazing

- including frame and sash

0.52 0.65

Performance Double Glazing (low-e)

- including frame and sash

0.37 0.52

Triple Glazing

- including frame and sash

0.18 0.37

Triple Glazing (argon filled cavity)

- including frame and sash

0 0.18

 

Glazing SHGC

Description Lower Upper
Clear Single Glazing 0.7 1
Clear Double Glazing 0.4 0.7
Reflective Coated Glazing 0.2 0.4
Glazing with Internal Blinds 0 0.2

 

Surface Reflectance

Description Lower Upper

Mirror Finish

- highly reflective 0.9 1

0.9 1

Light coloured walls

- reflective

0.6 0.9
Medium coloured walls 0.4 0.6
Dark coloured walls - low reflectivity 0.1 0.4
Black - very low reflectivity 0 0.1

 

Leakage (cfm/ft2 )

Description Lower Upper

Leaky building

0.55 and above

Normal practice

0.27 0.55
Best practice 0.05 0.27
Extremely tight building 0 0.05

 

Roof Thermal Resistance R-value (ft2 -h-°F/BTU)

Description Lower Upper

Uninsulated and single skin roofs

1.1 5

Poorly insulated

(approx. 50mm/2in insulation)

5 9

Insulated

(approx. 100mm/4in insulation)

9 22

Well insulated

(approx. 150mm/6in insulation)

 22  37

Extremely well insulated

37 and above

 

Floor Thermal Resistance R-value (ft2 -h-°F/BTU)

Description Lower Upper

Uninsulated and single skin roofs

1.1 1.4

Poorly insulated

(approx. 50mm/2in insulation)

1.4 4

Insulated

(approx. 100mm/4in insulation)

4 23

Well insulated

(approx. 150mm/6in insulation)

23  38

Extremely well insulated

38 and above

 

Walls Thermal Resistance R-value (ft2 -h-°F/BTU)

Description Lower Upper

Uninsulated and single skin roofs

1.1 5

Poorly insulated

(approx. 50mm/2in insulation)

5 11

Insulated

(approx. 100mm/4in insulation)

11 16

Well insulated

(approx. 150mm/6in insulation)

 16  38

Extremely well insulated

38 and above
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