NCC 2016 Volume Two
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Part 3.12.2 External Glazing

Part 3.12.2 External Glazing

3.12.2 Application

This Part applies to—

(a)

a Class 1 building; and

(b)

a Class 10a building with a conditioned space.

3.12.2.1 External glazing

(a)

The aggregate conductance of the glazing in each storey, including any mezzanine, of a building must—

(i)

not exceed the allowances resulting from—

(A)

in climate zone 1, multiplying the area of the storey, including any mezzanine, measured within the enclosing walls, by the constant CU obtained from Table 3.12.2.1; and

(B)

in climate zones 2 to 8, using the constant CU obtained from Table 3.12.2.1.

(ii)

be calculated in accordance with the following calculation—

(A)

in climate zone 1—

(A1 x U1) + (A2 x U2) + (A3 x U3) + ...................
where—
A1, 2, etc = the area of each glazing element; and
U1, 2, etc = the Total System U-Value of each glazing element; and
(B)

in climate zones 2 to 8—

[(A1 x U1) + (A2 x U2) + .......] / [(A1 x SHGC1 x EW1) + (A2 x SHGC2 x EW2) + ........ ]
where—
A1, 2, etc = the area of each glazing element; and
U1, 2, etc = the Total System U-Value of each glazing element; and
SHGC1, 2, etc = the Total System SHGC for each glazing element; and
EW1, W2 etc = the winter exposure factor for each glazing element obtained from Table 3.12.2.2a.
(b)

The aggregate solar heat gain of the glazing in each storey, including any mezzanine, of a building must—

(i)

not exceed the allowances resulting from multiplying the area of the storey, including any mezzanine, measured within the enclosing walls, by the constant CSHGC obtained from Table 3.12.2.1; and

(ii)

be calculated in accordance with the following calculation—

(A1 x SHGC1 x ES1) + (A2 x SHGC2 x ES2) + ........
where—
A1, 2, etc = the area of each glazing element; and
SHGC1, 2, etc = the Total System SHGC for each glazing element; and
ES1, S2 etc = the summer exposure factor for each glazing element obtained from Table 3.12.2.2b.

Explanatory information

Explanatory information:
  1. The conductance formula for climate zone 1 differs from the formula for all other climate zones because there is little or no need for heating at any time of the year in climate zones 1. The conductance allowance is calculated to limit the rate of heat conduction through glazing into an air conditioned interior from a hotter outside environment. The limit is set at a level that allows the use of basic glazing systems in dwellings with average glazing areas whether or not they are air conditioned.
  2. The conductance formula for climate zones 2 to 8 is based on wintertime conditions to account for the balance between potential solar gains and heat loss by conduction through glazing. The calculation favours orientations with higher potential solar gains in winter and the use of shading rather than glass toning. The improved insulation performance of glazing resulting from the calculations will also be beneficial under summertime conditions when outside temperatures exceed inside temperatures.
  3. By referring to “glazing elements”, 3.12.2.1 requires Total System U-Values and Total System SHGCs to be assessed for the combined effect of glass and frames. The measurement of these Total System U-Values and Total System SHGCs is specified in the Technical Protocols and Procedures Manual for Energy Rating of Fenestration Products by the Australian Fenestration Rating Council (AFRC).

    Various assessors using AFRC procedures might refer to their published performance values by slightly different terms including "U-factor" or "Uw" for Total System U-Value or "SHGC" for Total System SHGC. Such values can be used under 3.12.2.1 provided they measure the combined glass and frame performance according to AFRC requirements.

  4. Total System U-Values and Total System SHGCs are shown for some simple types of glazing elements in the table below (smaller numbers indicate better glazing element performance). The table gives worst case assessments, which can be improved by obtaining generic or custom product assessments from suppliers, manufacturers, industry associations (including their online resources) and from competent assessors.
WORST CASE WHOLE GLAZING ELEMENT PERFORMANCE VALUES
Glass description Aluminium framing Timber or uPVC framing
Total System U-Value
Single clear 7.9 0.81 5.6 0.77
Tinted single 7.9 0.65 5.6 0.61
Clear double (3/6/3) 6.2 0.72 3.8 0.68
  1. Typical ranges of generic ratings are set out in the table below to illustrate the levels of performance available through such assessments. Numbers from this table should not be used in compliance calculations.
INDICATIVE RANGES OF WHOLE GLAZING ELEMENT PERFORMANCE VALUES
Glass description Comment Aluminium framing Timber or uPVC framing
Single (monolithic or laminated)
Clear Minimal variation in glass U-Value and SHGC for different glass thicknesses. 7.9 – 5.5 0.81 – 0.64 5.6 – 4.3 0.77 – 0.51
Tinted Glass SHGC depends on glass thickness and type of tint. 7.9 – 5.6 0.65 – 0.33 5.6 – 4.3 0.61 – 0.25
Coated Glass U-Value and SHGC depend on coating type. 7.8 – 3.8 0.68 – 0.36 5.5 – 2.9 0.64 – 0.27
Tinted + coated Glass U-Value depends on coating type. Glass SHGC depends on coating type, type of tint and glass thickness. 7.8 – 3.8 0.45 – 0.31 5.5 – 3.1 0.42 – 0.23
Double
Clear Glass U-Value depends on cavity width. 6.2 – 3.1 0.72 – 0.63 3.8 – 2.5 0.68 – 0.47
Tinted Glass U-Value depends on cavity width. Glass SHGC depends on type of tint, tinted glass thickness and on cavity width. 6.2 – 3.1 0.57 – 0.36 3.8 – 2.5 0.57 – 0.27
Coated Glass U-Value depends on cavity width and type of coating. Glass SHGC depends on type of coating and cavity width. 6.2 – 2.4 0.60 – 0.22 3.8 – 2.1 0.59 – 0.17
Tinted + coated Glass U-Value depends on cavity width and type of coating. Glass SHGC depends on type of coating, tinted glass thickness and cavity width. 6.2 – 2.5 0.41 – 0.21 3.8 – 2.1 0.37 – 0.16
  1. Custom assessments consider glazing element components in most detail and return the highest levels of assessed performance for a given type of glazing element. Generic assessments consider the components of glazing elements in less detail and return lower levels of assessed performance.
  2. The calculations for conductance and solar heat gain both consider seasonal solar radiation, orientation, shading and the solar performance of the glazing.

Table 3.12.2.1 CONSTANTS FOR CONDUCTANCE AND SOLAR HEAT GAIN

Floor construction Air Movement (refer Notes) Constant
1 2 3 4 5 6 7 8
Floor in direct contact with the ground Standard C U 1.650
 18.387
 14.641
 7.929
 13.464
 6.418
 5.486
 3.987
C SHGC 0.063
 0.074
 0.062
 0.097
 0.122
 0.153
 0.189
 0.234
High C U 1.650
 18.387
 14.641
 7.929
 13.464
 6.418
 5.486
 3.987
C SHGC 0.069
 0.081
 0.068
 0.107
 0.134
 0.168
 0.208
 0.257
Suspended floor Standard C U 1.485
 16.548
 13.177
 7.136
 12.118
 5.776
 4.937
 3.588
C SHGC 0.057
 0.067
 0.056
 0.087
 0.110
 0.138
 0.170
 0.211
High C U 1.485
 16.548
 13.177
 7.136
 12.118
 5.776
 4.937
 3.588
C SHGC 0.063
 0.074
 0.062
 0.096
 0.121
 0.152
 0.187
 0.232

Notes:

  1. A storey has Standard air movement if all habitable rooms comply with Part 3.12.4.
  2. A storey has High air movement if the total ventilation opening area serving the habitable room is—
    1. in climate zones 1, 2, 3, 4 and 5, not less than that for Standard air movement without a ceiling fan or evaporative cooler, but with ceiling fans complying with 3.12.4.3 installed in all habitable rooms; or
    2. not less than twice that for Standard air movement without a ceiling fan or evaporative cooler.
  3. Where the ventilation opening area serving the habitable rooms is between Standard and High, interpolation may be used to determine the applicable CSHGC.
  4. Where the floor construction of a storey, including a mezzanine, is partly in direct contact with the ground and partly suspended, the constants for conductance and solar heat gain are to be—
    1. interpolated between the constants for the two constructions in proportion to their respective areas; or
    2. those for a suspended floor.

Explanatory information

Explanatory information:
  1. A floor in direct contact with the ground includes a concrete slab-on-ground or concrete slab-on-fill.
  2. A suspended floor includes a suspended timber floor, suspended steel framed floor or suspended concrete floor.
  3. In general, a floor in direct contact with the ground more readily assimilates solar heat gains than a suspended floor. Consequently, lower stringency levels apply to glazing in a storey that has a floor in direct contact with the ground.
  4. Whether a storey has Standard or High air movement depends upon the total ventilation opening area provided to habitable rooms on that storey and the presence of ceiling fans. The additional ventilation opening area required for High air movement without fans can be distributed to any of the habitable rooms on the storey. In climate zones 1 to 5, the storey can achieve High air movement when the total ventilation opening area is as for Standard air movement (without a ceiling fan or evaporative cooler) but with ceiling fans installed in every habitable room. For example, in climate zone 2:
Air movement With ceiling fans Without ceiling fans
Standard 10% 7.5%
High 20% 10%
  1. The provisions of 3.12.2 assume that internal window coverings will be installed for privacy reasons. This assumption is already incorporated in the allowances for glazing.

Table 3.12.2.2a WINTER EXPOSURE FACTOR (EW)

P/H (refer Figure 3.12.2.2) Orientation Sector (refer Figure 3.12.2.1)
North North east East South east South South west West North west
CLIMATE ZONE 1
Winter exposure factors are not needed for climate zone 1.
CLIMATE ZONE 2
0.00 1.86 1.44 0.86 0.40 0.37 0.41 0.91 1.48
0.05 1.80 1.37 0.80 0.34 0.31 0.36 0.84 1.42
0.10 1.73 1.33 0.76 0.32 0.29 0.34 0.81 1.34
0.20 1.51 1.18 0.68 0.29 0.27 0.30 0.73 1.20
0.40 1.25 0.95 0.54 0.24 0.23 0.25 0.61 0.99
0.60 1.04 0.78 0.48 0.21 0.20 0.22 0.51 0.83
0.80 0.78 0.62 0.39 0.18 0.19 0.20 0.44 0.68
1.00 0.54 0.53 0.32 0.17 0.18 0.17 0.37 0.56
1.20 0.33 0.42 0.28 0.15 0.17 0.16 0.35 0.46
1.40 0.28 0.36 0.23 0.14 0.16 0.15 0.31 0.38
1.60 0.22 0.29 0.22 0.14 0.15 0.14 0.26 0.34
1.80 0.19 0.25 0.19 0.13 0.14 0.13 0.23 0.28
2.00 0.15 0.19 0.17 0.12 0.14 0.13 0.22 0.27
CLIMATE ZONE 3
0.00 1.92 1.49 0.88 0.32 0.25 0.33 0.95 1.56
0.05 1.90 1.44 0.82 0.28 0.22 0.29 0.91 1.52
0.10 1.76 1.37 0.87 0.27 0.21 0.28 0.87 1.44
0.20 1.57 1.22 0.70 0.24 0.20 0.25 0.78 1.30
0.40 1.25 1.00 0.60 0.20 0.18 0.21 0.67 1.08
0.60 0.94 0.77 0.48 0.18 0.17 0.18 0.54 0.87
0.80 0.63 0.61 0.43 0.16 0.15 0.17 0.46 0.70
1.00 0.42 0.52 0.35 0.14 0.14 0.16 0.41 0.56
1.20 0.29 0.40 0.31 0.13 0.14 0.14 0.34 0.48
1.40 0.23 0.36 0.25 0.12 0.13 0.13 0.30 0.41
1.60 0.17 0.31 0.24 0.11 0.12 0.12 0.29 0.34
1.80 0.15 0.22 0.19 0.11 0.12 0.11 0.24 0.31
2.00 0.13 0.22 0.18 0.10 0.12 0.11 0.22 0.27
CLIMATE ZONE 4
0.00 1.97 1.51 0.83 0.39 0.35 0.39 0.85 1.53
0.05 1.93 1.45 0.76 0.33 0.29 0.33 0.79 1.47
0.10 1.91 1.40 0.74 0.31 0.28 0.31 0.75 1.42
0.20 1.62 1.28 0.67 0.28 0.25 0.28 0.68 1.28
0.40 1.48 1.09 0.56 0.24 0.22 0.24 0.58 1.10
0.60 1.22 0.90 0.49 0.21 0.19 0.21 0.49 0.90
0.80 1.06 0.74 0.43 0.19 0.18 0.19 0.44 0.75
1.00 0.85 0.66 0.37 0.17 0.16 0.17 0.37 0.64
1.20 0.61 0.51 0.33 0.15 0.16 0.16 0.34 0.56
1.40 0.47 0.47 0.30 0.14 0.15 0.15 0.30 0.47
1.60 0.34 0.41 0.28 0.14 0.14 0.14 0.26 0.41
1.80 0.26 0.35 0.25 0.13 0.14 0.13 0.24 0.35
2.00 0.24 0.32 0.22 0.12 0.13 0.12 0.22 0.29
CLIMATE ZONE 5
0.00 2.01 1.48 0.77 0.39 0.37 0.39 0.85 1.58
0.05 1.95 1.42 0.70 0.33 0.31 0.33 0.78 1.51
0.10 1.95 1.36 0.66 0.31 0.30 0.32 0.75 1.47
0.20 1.63 1.21 0.59 0.28 0.27 0.28 0.67 1.32
0.40 1.49 1.00 0.49 0.24 0.23 0.24 0.55 1.10
0.60 1.21 0.83 0.40 0.21 0.21 0.21 0.47 0.90
0.80 0.98 0.68 0.35 0.19 0.19 0.19 0.42 0.73
1.00 0.80 0.52 0.28 0.17 0.18 0.17 0.36 0.63
1.20 0.54 0.46 0.25 0.16 0.17 0.16 0.29 0.50
1.40 0.40 0.34 0.21 0.15 0.16 0.15 0.28 0.43
1.60 0.28 0.30 0.19 0.14 0.14 0.13 0.23 0.36
1.80 0.22 0.25 0.16 0.13 0.14 0.13 0.20 0.32
2.00 0.18 0.19 0.15 0.12 0.14 0.12 0.19 0.24
CLIMATE ZONE 6
0.00 1.90 1.43 0.80 0.45 0.43 0.45 0.88 1.53
0.05 1.84 1.35 0.73 0.38 0.36 0.38 0.81 1.45
0.10 1.82 1.30 0.70 0.36 0.34 0.36 0.76 1.42
0.20 1.56 1.17 0.62 0.32 0.30 0.32 0.70 1.30
0.40 1.43 1.01 0.53 0.27 0.26 0.27 0.60 1.10
0.60 1.22 0.86 0.45 0.23 0.23 0.23 0.52 0.95
0.80 1.08 0.73 0.38 0.21 0.21 0.22 0.46 0.79
1.00 0.86 0.58 0.34 0.19 0.19 0.19 0.39 0.69
1.20 0.70 0.54 0.29 0.18 0.17 0.18 0.36 0.58
1.40 0.53 0.41 0.26 0.16 0.17 0.17 0.32 0.52
1.60 0.44 0.37 0.22 0.15 0.16 0.15 0.28 0.44
1.80 0.32 0.30 0.21 0.14 0.15 0.14 0.27 0.40
2.00 0.25 0.27 0.20 0.13 0.14 0.14 0.24 0.32
CLIMATE ZONE 7
0.00 2.08 1.63 0.83 0.38 0.35 0.38 0.75 1.50
0.05 2.01 1.56 0.77 0.32 0.29 0.32 0.69 1.44
0.10 2.01 1.53 0.73 0.30 0.28 0.30 0.66 1.41
0.20 1.89 1.43 0.68 0.27 0.25 0.27 0.60 1.28
0.40 1.62 1.24 0.58 0.23 0.21 0.23 0.50 1.13
0.60 1.49 1.09 0.50 0.20 0.19 0.20 0.44 0.96
0.80 1.27 0.94 0.44 0.18 0.17 0.18 0.39 0.83
1.00 1.16 0.83 0.41 0.16 0.16 0.16 0.34 0.71
1.20 0.91 0.70 0.34 0.15 0.15 0.15 0.30 0.63
1.40 0.83 0.68 0.33 0.14 0.14 0.14 0.27 0.48
1.60 0.64 0.49 0.30 0.13 0.13 0.12 0.25 0.45
1.80 0.52 0.47 0.24 0.12 0.13 0.12 0.23 0.39
2.00 0.39 0.39 0.24 0.11 0.12 0.12 0.20 0.33
CLIMATE ZONE 8
0.00 1.93 1.48 0.81 0.47 0.45 0.47 0.81 1.46
0.05 0.73 1.87 1.41 0.39 0.38 0.39 0.73 1.39
0.10 1.85 1.36 0.70 0.37 0.35 0.37 0.70 1.34
0.20 1.56 1.22 0.63 0.33 0.32 0.33 0.63 1.20
0.40 1.41 1.02 0.51 0.28 0.27 0.28 0.51 0.99
0.60 1.18 0.83 0.44 0.24 0.24 0.24 0.44 0.82
0.80 1.00 0.68 0.37 0.21 0.22 0.21 0.36 0.67
1.00 0.79 0.59 0.32 0.20 0.20 0.19 0.30 0.58
1.20 0.54 0.46 0.28 0.18 0.19 0.18 0.27 0.47
1.40 0.44 0.42 0.25 0.17 0.18 0.17 0.24 0.38
1.60 0.31 0.31 0.21 0.16 0.17 0.15 0.22 0.32
1.80 0.23 0.28 0.19 0.14 0.16 0.14 0.19 0.29
2.00 0.19 0.25 0.16 0.14 0.15 0.14 0.17 0.23
Note: For exposure factors with P/H values between those shown in Table 3.12.2.2a, either use the next highest P/H value or interpolate.

Table 3.12.2.2b SUMMER EXPOSURE FACTOR (ES)

P/H (refer Figure 3.12.2.2) Orientation Sector (refer Figure 3.12.2.1)
North North east East South east South South west West North west
CLIMATE ZONE 1
0.00 0.52 0.84 1.29 1.24 0.87 1.27 1.32 0.85
0.05 0.44 0.74 1.19 1.13 0.75 1.17 1.23 0.75
0.10 0.41 0.68 1.11 1.07 0.68 1.09 1.15 0.69
0.20 0.37 0.59 1.01 0.94 0.55 0.94 1.00 0.60
0.40 0.30 0.45 0.79 0.69 0.42 0.75 0.83 0.47
0.60 0.25 0.37 0.66 0.59 0.34 0.60 0.66 0.38
0.80 0.22 0.31 0.53 0.47 0.30 0.52 0.58 0.32
1.00 0.19 0.26 0.45 0.41 0.25 0.43 0.48 0.28
1.20 0.18 0.23 0.37 0.33 0.22 0.39 0.42 0.26
1.40 0.17 0.21 0.32 0.30 0.22 0.32 0.37 0.22
1.60 0.15 0.18 0.28 0.26 0.18 0.29 0.34 0.21
1.80 0.13 0.18 0.27 0.22 0.17 0.28 0.30 0.18
2.00 0.12 0.17 0.23 0.21 0.16 0.24 0.28 0.17
CLIMATE ZONE 2
0.00 0.72 1.05 1.22 1.04 0.72 1.12 1.34 1.11
0.05 0.60 0.92 1.10 0.92 0.60 1.01 1.23 0.99
0.10 0.55 0.85 1.04 0.86 0.57 0.94 1.14 0.90
0.20 0.47 0.74 0.92 0.76 0.50 0.84 1.00 0.78
0.40 0.39 0.56 0.73 0.61 0.40 0.67 0.83 0.60
0.60 0.33 0.44 0.60 0.49 0.33 0.55 0.67 0.45
0.80 0.29 0.37 0.50 0.41 0.29 0.46 0.58 0.39
1.00 0.26 0.30 0.43 0.35 0.24 0.40 0.47 0.32
1.20 0.23 0.27 0.35 0.30 0.22 0.34 0.41 0.28
1.40 0.21 0.24 0.32 0.28 0.21 0.30 0.36 0.24
1.60 0.19 0.23 0.28 0.25 0.19 0.27 0.31 0.22
1.80 0.17 0.20 0.24 0.22 0.17 0.26 0.28 0.20
2.00 0.17 0.19 0.22 0.21 0.16 0.22 0.27 0.19
CLIMATE ZONE 3
0.00 0.56 1.04 1.42 1.18 0.66 1.16 1.36 1.01
0.05 0.47 0.94 1.32 1.08 0.57 1.05 1.26 0.90
0.10 0.44 0.85 1.25 1.02 0.54 0.99 1.19 0.83
0.20 0.38 0.73 1.10 0.90 0.46 0.87 1.06 0.73
0.40 0.32 0.56 0.88 0.71 0.38 0.72 0.84 0.56
0.60 0.28 0.43 0.74 0.58 0.31 0.57 0.71 0.44
0.80 0.24 0.35 0.59 0.47 0.27 0.50 0.60 0.35
1.00 0.20 0.29 0.50 0.40 0.24 0.43 0.53 0.29
1.20 0.19 0.26 0.42 0.34 0.21 0.37 0.43 0.26
1.40 0.17 0.22 0.35 0.31 0.20 0.32 0.41 0.23
1.60 0.17 0.20 0.33 0.27 0.16 0.31 0.35 0.21
1.80 0.15 0.19 0.30 0.24 0.16 0.28 0.33 0.19
2.00 0.15 0.18 0.25 0.24 0.15 0.24 0.27 0.17
CLIMATE ZONE 4
0.00 0.72 1.19 1.40 1.05 0.57 0.99 1.31 1.12
0.05 0.61 1.10 1.31 0.97 0.49 0.91 1.22 1.02
0.10 0.56 1.00 1.24 0.91 0.46 0.85 1.17 0.94
0.20 0.43 0.87 1.12 0.82 0.41 0.76 1.05 0.81
0.40 0.30 0.66 0.92 0.67 0.34 0.62 0.85 0.62
0.60 0.27 0.50 0.74 0.56 0.29 0.53 0.72 0.45
0.80 0.24 0.38 0.63 0.49 0.25 0.45 0.59 0.36
1.00 0.20 0.31 0.55 0.42 0.22 0.39 0.51 0.30
1.20 0.19 0.26 0.46 0.37 0.20 0.35 0.45 0.25
1.40 0.16 0.23 0.39 0.34 0.17 0.33 0.38 0.21
1.60 0.16 0.20 0.38 0.30 0.16 0.29 0.33 0.20
1.80 0.14 0.18 0.32 0.27 0.14 0.25 0.32 0.17
2.00 0.13 0.17 0.28 0.23 0.14 0.24 0.26 0.16
CLIMATE ZONE 5
0.00 0.82 1.09 1.19 0.96 0.68 1.04 1.30 1.16
0.05 0.69 0.96 1.07 0.85 0.57 0.92 1.19 1.04
0.10 0.63 0.88 1.01 0.79 0.54 0.86 1.11 0.94
0.20 0.51 0.76 0.89 0.70 0.48 0.76 0.99 0.83
0.40 0.39 0.58 0.71 0.57 0.38 0.62 0.81 0.62
0.60 0.35 0.46 0.58 0.47 0.33 0.51 0.65 0.48
0.80 0.30 0.37 0.50 0.40 0.28 0.43 0.52 0.40
1.00 0.26 0.31 0.42 0.34 0.25 0.37 0.46 0.31
1.20 0.24 0.26 0.36 0.30 0.22 0.33 0.40 0.27
1.40 0.21 0.23 0.32 0.27 0.20 0.29 0.34 0.24
1.60 0.20 0.22 0.29 0.23 0.18 0.27 0.30 0.21
1.80 0.18 0.20 0.25 0.21 0.17 0.23 0.27 0.20
2.00 0.17 0.17 0.24 0.21 0.16 0.21 0.25 0.19
CLIMATE ZONE 6
0.00 0.84 1.08 1.15 0.87 0.61 1.05 1.40 1.24
0.05 0.71 0.97 1.05 0.78 0.52 0.96 1.30 1.13
0.10 0.65 0.90 0.99 0.74 0.49 0.91 1.25 1.04
0.20 0.52 0.77 0.88 0.65 0.44 0.82 1.12 0.91
0.40 0.36 0.58 0.71 0.54 0.36 0.67 0.90 0.69
0.60 0.30 0.43 0.61 0.45 0.31 0.58 0.76 0.51
0.80 0.26 0.35 0.50 0.38 0.26 0.50 0.66 0.40
1.00 0.22 0.29 0.42 0.32 0.23 0.42 0.56 0.36
1.20 0.20 0.24 0.37 0.29 0.23 0.39 0.48 0.29
1.40 0.18 0.22 0.32 0.26 0.19 0.34 0.42 0.26
1.60 0.16 0.19 0.28 0.24 0.18 0.31 0.38 0.21
1.80 0.15 0.18 0.26 0.22 0.17 0.28 0.34 0.20
2.00 0.14 0.17 0.24 0.21 0.17 0.26 0.31 0.17
CLIMATE ZONE 7
0.00 0.96 1.17 1.21 0.94 0.64 0.91 1.19 1.18
0.05 0.83 1.05 1.10 0.83 0.54 0.81 1.09 1.07
0.10 0.76 0.97 1.04 0.80 0.51 0.76 1.03 0.98
0.20 0.62 0.85 0.93 0.70 0.45 0.68 0.91 0.86
0.40 0.40 0.65 0.76 0.58 0.38 0.55 0.74 0.64
0.60 0.32 0.51 0.65 0.50 0.33 0.47 0.63 0.51
0.80 0.28 0.40 0.54 0.44 0.28 0.41 0.53 0.40
1.00 0.25 0.33 0.48 0.37 0.25 0.35 0.44 0.32
1.20 0.22 0.28 0.41 0.34 0.23 0.31 0.38 0.27
1.40 0.19 0.23 0.36 0.30 0.21 0.28 0.33 0.24
1.60 0.18 0.21 0.33 0.27 0.20 0.26 0.31 0.21
1.80 0.17 0.20 0.28 0.24 0.18 0.24 0.27 0.19
2.00 0.16 0.19 0.27 0.23 0.18 0.21 0.25 0.18
CLIMATE ZONE 8
0.00 0.85 1.12 1.20 0.96 0.68 1.01 1.27 1.16
0.05 0.71 0.99 1.09 0.85 0.57 0.90 1.16 1.04
0.10 0.65 0.90 1.02 0.79 0.54 0.84 1.09 0.95
0.20 0.52 0.79 0.90 0.70 0.48 0.73 0.98 0.83
0.40 0.39 0.60 0.73 0.57 0.39 0.61 0.79 0.63
0.60 0.34 0.46 0.60 0.48 0.33 0.50 0.66 0.49
0.80 0.30 0.37 0.50 0.41 0.29 0.43 0.53 0.40
1.00 0.25 0.30 0.42 0.35 0.25 0.37 0.47 0.33
1.20 0.23 0.28 0.37 0.31 0.23 0.33 0.39 0.26
1.40 0.21 0.23 0.32 0.29 0.20 0.29 0.34 0.24
1.60 0.20 0.21 0.30 0.25 0.18 0.25 0.31 0.22
1.80 0.19 0.20 0.25 0.22 0.17 0.23 0.28 0.20
2.00 0.16 0.18 0.23 0.21 0.16 0.22 0.24 0.19
Note: For exposure factors with P/H values between those shown in Table 3.12.2.2b, either use the next lowest P/H value or interpolate.

Explanatory information

Explanatory information:
  1. Higher exposure factor (EW) values in Table 3.12.2.2a indicate greater exposure to desirable winter solar gains and should be adopted as far as possible.
  2. Higher exposure factor (ES) values in Table 3.12.2.2b indicate greater exposure to unwanted summer solar gains and should be avoided as far as possible.

Figure 3.12.2.1

ORIENTATION SECTORS

v2_Fig31221_2007.svg

Explanatory information

Explanatory information:
  1. The orientation sector for a wall or glazing element is the sector that contains a line drawn perpendicular to the face of the wall or glazing element.
  2. Figure 3.12.2.1 is based on True North and all angles are measured clockwise from True North. Survey angles on site plans are usually marked in angles from True North. These angles can be used to establish True North for a particular site.
  3. Magnetic North, found by a magnetic compass, varies from True North over time and by different amounts in different locations. Magnetic North is not an acceptable approximation of True North.
  4. The eight orientation sectors shown in Figure 3.12.2.1 do not overlap at their boundaries. For example, north sector begins just clockwise after the NNW line and ends exactly on the NNE line. The start and end of other sectors are determined in a similar way, as indicated by the outer curved arrows.

Figure 3.12.2.2

METHOD OF MEASURING P AND H

v2_Fig31222_2006.svg

Notes:

  1. An external shading device that complies with 3.12.2.2(b) is considered to achieve a P/H value of 2.00.
  2. Where G exceeds 500 mm, the value of P must be halved.

3.12.2.2 Shading

Where shading is required to comply with , it must—

(a)

be provided by an external permanent projection, such as a verandah, balcony, fixed canopy, eaves, shading hood or carport, which—

(i)

extends horizontally on both sides of the glazing for a distance not less than the projection distance P in Figure 3.12.2.2; or

(ii)

provide the equivalent shading to (i) with a reveal or the like; or

(b)

be provided by an external shading device, such as a shutter, blind, vertical or horizontal building screen with blades, battens or slats, which—

(i)

is capable of restricting at least 80% of the summer solar radiation; and

(ii)

if adjustable, is readily operated either manually, mechanically or electronically by the building occupants.

Explanatory information

Explanatory information:
  1. Shading devices can include fixed louvres, shading screens and other types of perforated or fixed angle slatted shades. However, such devices need to be designed for the climate and latitude to ensure that summer sun penetration is restricted, while winter sun access is achieved. Winter access refers to the availability of winter solar gains to offset conducted heat losses.
  2. The impact of shading is assessed with respect to the solar heat gain for the window. The requirements of 3.12.2.1 considers solar heat gain to be either beneficial or detrimental to the energy efficiency of a building based on seasonal variation (winter/summer), climate zone, orientation and P/H. Higher P/H values are more beneficial in minimising summer solar heat gain where as lower P/H values are more beneficial in allowing winter access.
  3. Gutters can only be considered as providing shading if attached to a shading projection such as a verandah, fixed canopy, eaves, shading hood, balcony or the like.
  4. Shading devices can be either attached or located adjacent to the building. For example, a free-standing lattice screen may be considered to provide shading to glazing if it complies with 3.12.2.2(b).