Changes made to the Building Code of Australia (BCA) have introduced new requirements for artificial lighting that may restrict the amount of lighting in and around the home. The provisions were introduced nationally on 1 May 2010 through the 6 Star energy provisions in BCA 2010 Volume 2 (Housing Provisions) though most States and territories have delayed the introduction of 6 Star until 2011. Therefore the new lighting provisions will apply in most States and Territories from 1 May 2011. Two different approaches can be adopted that will restrict the total maximum power of lights or lighting systems in a space, measure in Watts per M2. Depending on what approach is adopted, the Lamp Power Density, defined as the rating of the lights in a space or the Illumination Power Density, which is the total power of the lighting system in a space must not exceed limits given in the BCA.
If adopting the Illumination Power Density method other factors such as current regulators and control devices are considered and can provide a more generous outcome.
Calculating using Lamp power density Using the Lamp Power Density method only requires the total power of the light fittings to be determined along with the area of the space to ensure the limit in the BCA is not exceeded. To determine if the proposed lighting complies is simply a matter of dividing the total watts of the lighting by the floor area.in a Class 1 (house) the limit per M2 is 5 watts; For balconies or verandah’s the calculation method is the same but the total watts allowed is 4 watts per M2 and for Class 10 buildings & 3 Watts per M2.
Calculating using Illumination power density The Illumination Power Density method takes into account the whole lighting system including current regulators, control devices and the like and using the adjustment factors provided in the BCA for certain types of control devices the maximum watts in a space can be increased. It is also important to note that when using the Illumination Power Density adjustment factor method there is no concession for tungsten halogen or other incandescent lights if using daylight sensors if the lights are within a certain distance of a window or adjacent to a roof light. This is to encourage the use of natural lighting and only allow more energy efficient lighting in these situations.
Exterior lighting For lighting around the perimeter of the building, i.e. spot lights under eaves, there are separate requirements in that they must be controlled by a daylight sensor or have a certain level of efficiency. It is too difficult to use the Watts per M2 method for exterior lighting as there are no defined ‘spaces’.
Dessity to calculate the energy use of lighting.
The following is a worked example using Lamp Power Density and Illumination Power
Calculating using the Lamp Power Density method
Step one - Determine room area:- Measure inside walls 4m x 6m = 24m2 Step two – Determine lamp capacity ;- 60 Watts x 2 = 120 Watts (Lamp Watts x number of lamps) Step three – Determine the Lamp Power Density;- 120 Watts / 24m2 = 5.0W/m2
Calculating using the Illumination Power Density method
This method provides a concession using control devices such as motion detectors, dimming systems and daylight sensors. An adjustment factor is included in the calculations; the adjustment factor will vary depending on the control device. The procedure is the same as for Lamp Power Density but the control device will provide a more generous target.
Step One -Determine room area:- · Measure inside walls 4m x 6m = 24m2 Step Two – Divide the allowable Illumination Power Density by the adjustment factor for a motion detector (a motion detector provides an adjustment factor of 0.9 in the BCA) 5W/m2 / 0.9 = 5.5W/m2 ·Step Three – Determine total wattage of power system (Illumination Power Density) and ensure it does not exceed the revised value of 5.5 W/m2· 120 Watts / 24m2 = 5.0 W/m2 On a 4m x 6m room (24sq mtr) Two 60 Watt lamps 5.0 W/m2 is equivalent to the allowed 5 W./m2 Therefore the lamps comply 5.0 W/m2 is less than the allowed 5.5 W/m2. Therefore the lamps comply
Note the amount of lighting can be increased to a maximum of 5.5 W/m2
The above is intended to provide general information in summary form. The contents do not constitute specific advice and should not be relied upon as such. Formal specific advice should be sought by members with respect to particular matters before taking action.
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For further information HIA members can contact HIA’s Building Services staff on 1300 650 620 or hia_technical@hia.com.au.
This article was published on Friday 05 August, 2011.
