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Part 3.8.4 Light
Appropriate Performance Requirements
Appropriate Performance Requirements
Where an alternative light system is proposed as a Performance Requirement to that described in Part 3.8.4, that proposal must comply with—
- Performance RequirementP2.4.4; and
- the relevant Performance Requirements determined in accordance with A2.2(3) and A2.4(3) as applicable.
3.8.4.1 Application
Compliance with this acceptable construction practice satisfies Performance Requirement P2.4.4 for light.
3.8.4.2 Natural light
Natural light must be provided to all habitable rooms, in accordance with the following:
(a)
Natural light must be provided by—
(i)
windows, excluding roof lights that—
(A)
have an aggregate light transmitting area measured exclusive of framing members, glazing bars or other obstructions of not less than 10% of the floor area of the room; and
(B)
are open to the sky or face a court or other space open to the sky or an open verandah, carport or the like; or
(ii)
roof lights that—
(A)
have an aggregate light transmitting area measured exclusive of framing members, glazing bars or other obstructions of not less than 3% of the floor area of the room; and
(B)
are open to the sky; or
(iii)
a proportional combination of windows and roof lights required by (i) and (ii).
Explanatory information:
Explanatory information:
A roof light generally receives greater exposure to sunlight than a window because of its orientation to the sky and consequently, the size of a roof light as a percentage of the floor area served is permitted to be smaller than for a window serving the same floor area.
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Method for determining proportional combination of windows and roof lights . |
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Description of above diagram |
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Area of the room which requires natural light is 100 m2. |
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No natural light borrowed from adjoining rooms. |
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General requirements |
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Requiredwindow(s) to provide natural light must have a light transmitting area of at least 10% of the floor area. |
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10% of 100 m 2 = 10 m 2 |
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Or, roof light(s) to provide natural light must have a light transmitting area of at least 3% of the floor area. |
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3% of 100 m 2 = 3 m 2 |
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In the formula below, 3% of the floor area is expressed as the fraction 0.03 and 10% of the floor area is expressed as the fraction 0.1. |
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Calculations |
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Formula — for the area of window(s) required to compensate for roof light(s) short fall |
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Area of room covered by the roof light(s) = (Area of roof light(s)) / 0.03 |
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= [(floor area) – (Area covered by the roof light(s))] / 10 |
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Area of window(s) required to compensate for roof light(s) short fall |
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If the roof light(s) = 1 m² |
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Area of room covered by the roof light(s) = (1 m2 / 0.03) |
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= 33.33 m2 |
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= (100 m2 – 33.33 m2) / 10 |
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= 6.67 m2 |
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Formula — for the area of roof light(s) required to compensate for window(s) short fall |
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Area of room covered by the window(s) = (Area of window(s)) / 0.1 |
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= [(floor area) – (Area covered by the window(s))] / 33.33 |
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Area of roof light(s) required to compensate for window(s) short fall |
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If the window(s) = 5 m² |
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Area of room covered by the window(s) = (5 m2 / 0.1) |
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= 50 m2 |
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= (100 m2 – 50 m2) / 33.33 m2 |
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= 1.5 m2 |
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Notes:
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(b)
(c)
Natural light to a room may come through one or more glazed panels or openings from an adjoining room (including an enclosed verandah) if—
(i)
the glazed panels or openings have an aggregate light transmitting area of not less than 10% of the floor area of the room to which it provides light; and
(ii)
the adjoining room has—
(A)
windows, excluding roof lights that—
(aa)
have an aggregate light transmitting area of not less than 10% of the combined floor area of both rooms; and
(bb)
are open to the sky or face a court or other space open to the sky or an open verandah, carport or the like; or
(B)
roof lights that—
(aa)
have an aggregate light transmitting area of not less than 3% of the combined floor area of both rooms; and
(bb)
are open to the sky; or
(C)
a proportional combination of windows and roof lights required by (A) and (B).
(iii)
(see Figure 3.8.4.1)
Explanatory information:
Explanatory information:
- Direct natural light provided from another source is intended to mean light from a window or r oof light in the subject room. As the provision relates to natural light obtained from an adjoining room, "another source" refers to direct natural light provided to the subject room which does not meet the required allowance of either 10% or 3% of the floor area of that room. By not meeting the required amount of natural light, the "direct natural light from another source" can be used as a supplement to the natural light required from an adjoining room.
- To borrow natural light from another room, 3.8.4.2(c)(i) allows light to pass through a glazed panel(s) or opening(s) from an adjoining room, which under 3.8.4.2(c)(ii), must have windows, r oof lights or a combination of windows and r oof lights of a minimum size in proportion to the combined floor areas of both rooms. The minimum size of the glazed panel(s) or opening(s), and the minimum size of the window to the adjoining room are illustrated in Figure 3.8.4.1.
- If a doorway is used as an opening to obtain natural light, it must do so when in the closed position (see Figure 3.8.4.1).
Figure 3.8.4.1 Method of determining areas of openings for borrowed light
3.8.4.3 Artificial lighting
Sanitary compartments, bathrooms, shower rooms, airlocks and laundries must be provided with artificial lighting if natural light in accordance with the relevant provisions of 3.8.4.2 is not available—
(a)
at a rate of not less than one light fitting per 16 m2 of floor area; or
(b)
in accordance with AS/NZS 1680.0.