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The BASIX definition

The BASIX definitions, dated: 06 October 2017, are listed in alphabetical order below:

A - DE - HI - LM - PQ - TU - Z


1 Star, 2 Star, 3 Star, 4 Star or 5 Star: in relation to an electrical system or appliance, means the Energy Star Rating as determined under the Electricity Safety (Equipment Efficiency) Regulation 1999 and, in relation to a gas system or appliance, means the Energy Star Rating as specified by the Australian Gas Association (AGA).

1 star, 2 star, 3 star, 4 star, 5 star or 6 star: In relation to a water using fixture or appliance (clothes washer and dishwasher), means the fixture or appliance is rated to that level of water efficiency in accordance with AS/NZS 6400:2005 Water efficient products rating and labelling.


Accredited Assessor: means a person accredited by an Accrediting Organisation to conduct Simulations for the Thermal Comfort Index of BASIX.

Accrediting Organisation: means an organisation approved by the Department to accredit assessors for the purposes of conducting Simulations.

Active power factor correction: means the correction of the power factor of an electrical system by equipment in order to reduce power losses in the supply of electricity to that system.

Alternative energy system: means a system which generates electricity on the land the subject of the application, using an energy source other than the electricity supply grid, and includes a photovoltaic power system and a wind generator.

Alternative water: means water that is not mains-supplied potable water.

Alternative water supply system: means a system that supplies water other than mains-supplied potable water.

Assessor Certificate: means the Nationwide House Energy Rating Scheme Certificate issued from the online generation system by the software provider, with the first page showing the NatHERS logo and the total heating and cooling loads and the unique QR-code.

Note: Assessor Certificate generated prior to 1 May 2016 may consist of, for each dwelling in that building project, the NatHERS Certificate (1 page) and the Building Thermal Performance feature report (3-5 pages) generated by the Approved Software, with every page showing the Assessor Stamp.

Assessor Certificate Number: means the unique Certificate Number shown on the Assessor Certificate.

Note: Assessor Certificate generated prior to 1 May 2016 may have the Assessor Certificate Number issued by the Accrediting Organisation for the Simulations conducted by an Accredited Assessor on the building's thermal performance.

Assessor Stamp:  means the unique stamp, issued by the Accrediting Organisation, that is used by the Accredited Assessor to endorse the Simulation inputs and outputs for the building project. The Assessor Stamp may be found in Assessor Certificate generated prior to 1 May 2016.

Attached dwelling house: means a dwelling which is attached to, or less than 0.5m from, any other dwelling or building (excluding a garage or carpark), but which does not have another dwelling or building (excluding a garage or carpark) above or below it, such as a semi-detached house, terrace house, row house or townhouse.


Breeze path: means a path of air flow within a dwelling between two ventilation openings.

Biodiesel: means an alternative diesel fuel that is not petroleum based, but is made from renewable resources such as vegetable oils, animal fats or algae.

Building Code of Australia: means the document published by or on behalf of the Australian Building Codes Board, together with:

(a) such amendments made by the Australian Building Codes Board, and

(b) such variations approved by the Australian Building Codes Board in relation to New South Wales.

Building Management System (BMS): means a system designed to control, monitor and optimise various building services, including lighting, heating, ventilation, cooling, swimming pool pumps and water use in cooling towers.


Central system or facility: means a system or facility that services more than one dwelling.

Central ducted: in relation to a ventilation system, means a system where mechanical ventilation is provided from a central ventilation system.

Closed system: in relation to a fire sprinkler test water system, means a system where water used to test the fire sprinkler system is stored for reuse during the next test.

CO monitoring: in relation to a carpark efficiency measure, means an off/on switching based on monitored levels of carbon monoxide.

Coefficient of Performance (COP): in relation to cooling and heating systems, means the capacity of output divided by the power input.

Cogeneration heat: means the usable heat that is directly produced by a cogeneration system.

Cogeneration heat absorption: means absorption chilling that is driven by cogeneration heat.

Cogeneration heat boiler: means a boiler that is heated using cogeneration heat.

Cogeneration system: means a system that simultaneously produces power (electrical or mechanical) and cogeneration heat (for example to heat water) from the same fuel in a single thermodynamic process.

Committed capacity: in relation to a system, means the capacity which the system was required to have at the time it was installed, under any earlier development consent or complying development certificate.

Common area: means spaces within the development site that can be used by the occupants of more than one dwelling or services more than one dwelling, and includes shared open space, shared lobbies, corridors, gyms, pools, car parks and common service areas such as plant rooms and garbage areas.

Conditioned floor area: in relation to a dwelling, means the total floor area of the dwelling, excluding: 
a) floor area that is not fully enclosed; 
b) bathrooms (but not ensuites) and laundries, with a ventilation opening; and voids, store rooms, garages and carparks.

Conductivity controller: in relation to a cooling tower or evaporative cooling system, means a device used to manage the concentration of dissolved solids by automatically controlling waterbleed.

Cooling load: for a dwelling, means the value specified for cooling load on an Assessor Certificate for the dwelling.

Cooling tower: means a device for lowering the temperature of water by evaporative cooling, where atmospheric air is in contact with falling water, thereby resulting in the exchange of heat.

Corrected cooling load: means the cooling load adjusted by BASIX to account for any complying breeze paths in the dwelling.


Dedicated: in relation to light fittings, means a light fitting that is only capable of accepting fluorescent or LED (Light Emitting Diode) lamps. It will not accept incandescent, halogen or any other non-fluorescent or non-LED lamps.

The Department: means the NSW Department of Planning and Environment, or its precursors and successors, including any government office, agency or corporation that is responsible for the administration of the Environmental Planning and Assessment Act 1979.

Dwelling: means a room or suite of rooms occupied or used or so constructed or adapted as to be capable of being occupied or used as a separate domicile.


Energy Efficiency Ratio (EER): in relation to cooling and heating systems, means the capacity of output divided by the power input.


Floor area: means the area of floor measured within the finished surfaces of the walls, and includes the area occupied by any cupboard or other built-in furniture item, fixture or fitting.


Garage: means an enclosed space used for storage of motor vehicles, and does not include (a) open carports, or (b) external outbuildings such as garden sheds or workshops.

Garden: means all areas planted with vegetation excluding lawn.

Gas-fired storage (manifolded): means a type of central hot water system comprised of a number of small-scale gas storage hot water systems connected together.

Geared traction with VVAC motor: in relation to a lift system, means a system with geared traction that is powered with a variable voltage alternating current motor.

Gearless traction with VVVF motor: in relation to a lift system, means a system with gearless traction that is powered with a variable voltage variable frequency motor.

Granny flat: see Secondary dwelling.

Greywater: means waste water that does not contain human excreta, such as water from the laundry or from the bathroom (but not toilet).

Greywater diversion system: means a system for the diversion (but not the treatment or storage) of greywater.

Greywater treatment system: means a system for the collection, treatment and storage of greywater.

Ground floor: in relation to the 'Thermal Comfort' section of BASIX, means the lowest floor, or part thereof, of the dwelling with a habitable room.

Groundwater: means water that exists beneath the earth's surface in underground streams and aquifers.


Habitable room: means any room of a dwelling excluding a bathroom, laundry, toilet, pantry, walk-in wardrobe, corridor, stair, lobby, photographic darkroom, clothes drying room or other room or area of a specialised nature which is not occupied frequently or for extended periods.

Heat pump: means a device that causes heat to flow from one place to another at a rate greater than it might have otherwise flowed in the absence of pumping.

Heating load: for a dwelling, means the value specified for heating load on an Assessor Certificate for the dwelling.

Hot water diversion system: means a system that, on demand, diverts cold water sitting in the hot water pipe away from fixtures to a holding tank, which can then be used as an alternative water source.


Indigenous species: means a species of vegetation which the relevant local council deems is an indigenous species in that area - see here for more information.

Individual fan into central duct + VSD: in relation to a ventilation system, means an exhaust fan within an individual dwelling, which is connected into a common exhaust duct serving multiple dwellings and having a central fan which is controlled by a variable speed drive.

Individual fan, ducted to façade or roof: in relation to a ventilation system, means an exhaust fan that services only one dwelling, where the ventilation exhaust is ducted directly to either the roof or an outside wall.

Individual fan, not ducted: in relation to a ventilation system, means an exhaust fan which is not ducted (but is window-mounted, wall-mounted or ceiling-mounted) and services only one room in an individual dwelling.

Individual system: means a system that services one dwelling only.

Instantaneous: in relation to a hot water system, means a system where water is heated as it is required (for example when a tap is turned on), without the use of storage tanks.

Interlocked to light: in relation to a ventilation system, means the ventilation system is switched off/on as the light is switched off/on.


Lighting control system: means a system designed to control, monitor and optimise the efficiency of lighting.

Low water use species: means a species of vegetation identified as a 'one drop plant' under Sydney Water's Plant Selector Water Drop Rating Scheme (available at, or a species of vegetation which the local council for that area deems is a low water use species in that area.


Main living area: in relation to a dwelling, means the living area (being an area bounded by enclosing walls, doorways, or apertures in enclosing walls that are less than 3m2) with the greatest floor area.

Make-up line: means a line that provides water to a cooling tower or evaporative cooling system to replenish water lost through evaporation, bleed, drift and wastage.

Manual on / timed off: means a switch that must be manually switched on, but switches off automatically after a set amount of time.

Mechanical ventilation: means ventilation provided by a powered system such as an electrically driven fan.

Mezzanine: means habitable areas open to and above a habitable floor, and does not include stair or stair landings or open passageways, gantries or corridors 1.1m or less wide.

Motorised damper into central duct + VSD: in relation to a ventilation system, means a common exhaust system serving more than one dwelling and having a central fan which is controlled by a variable speed drive, with duct connections to individual dwellings each having a motorised damper that is open when exhaust is required and closed when not required.


Non-residential floor area: means the floor area of a development that is used for non-residential purposes, and includes retail, office, and restaurant areas and their associated areas such as storage areas and kitchens. "Non-residential floor area" does not include any common area that services both residential and non-residential parts of a development such as a lobby, carpark or loading bays.


On-demand hot water recirculation system: means a system that, on demand, recirculates cold water sitting in the hot water pipe back to the water heating system for heating before use, as a means of saving water. It does not include continuously recirculating or timed hot water recirculation systems.

Orientation: in relation to a part of a dwelling, means the direction in which the part of the dwelling faces, in accordance with the following sectors of a compass (based on true north): N = >337.5 - 22.5, NE = >22.5 - 67.5, E = >67.5 - 112.5, SE = >112.5 - 157.5,S = >157.5 - 202.5, SW = >202.5 - 247.5, W = >247.5 - 292.5, NW = >292.5 - 337.5.

Out-building: means a smaller separate building such as a shed or barn that belongs to a main building, such as a house or farm.


Photovoltaic system: means a system consisting of flat panels, typically made from silicon, that are installed in an unshaded location and directly convert sunlight into electricity.

Piping insulation (ringmain and supply riser): in relation to a central hot water system, means the insulation of the central piping circuit (ie. ringmain) and the piping which supplies individual apartments ( risers).

Planter box: means a fixed garden with an impermeable base.

Potable water: means water fit for human consumption.

Primary type of artificial lighting: in relation to a room or area, means that at least 80% of light fittings in that room or area are of that type, including the main light fitting.

Private landscaping: for a dwelling, means landscaping that is for the private use of occupants of the dwelling (and is not a common area).

Protected: in relation to a pool or spa, means protected from wind by a solid fence or dense vegetation. 


R-Value (R1.0, R2.0 etc): means the thermal resistance (m2.K/W) of a component calculated by dividing its thickness by its thermal conductivity.

Rainwater: means water discharged from non-trafficable roof areas within a development site.

Rainwater Tank for pool/spa top-up: A tap connected to the rainwater tank must be located within 10 metres of the edge of the pool/spa.

Recycled water: means water such as grey water, stormwater and other types of wastewater, that have been treated for reuse.

Reticulated alternative water: means recycled water that is supplied by a water utility or central authority via a reticulated system to individual lots for non-potable use.

Roof area: means the area of all roof surfaces measured to the outside of the gutters, excluding parapets and trafficable roof terraces, and measured in the horizontal plane.


Secondary dwelling: means a self-contained dwelling that is: (a) established in conjunction with another house (the principle dwelling), and (b) on the same lot of land, (not being an individual lot in a strata plan or community title scheme) and (c) located either within the house, or attached to the house, or separate from the house.

Separate dwelling house: means a dwelling which is separated from all other dwellings and other buildings (excluding a garage or carpark) by at least 0.5m.

Separate lot: means a land parcel containing only one dwelling and not subject to further sub-division, strata title or community title.

Shaded: Shaded in relation to a pool or spa means that at least 80% of the pool or spa is covered by a shading device such as a shade cloth or roof structure. The shading material must satisfy one of the following: be opaque, have a shade ratio of not less than 80%, or have a shading co-efficient of less than 0.35.

Sheltered: in relation to a clothes drying line, means completely sheltered from rain.

Site area: means the area of land on which the proposed development is to be carried out.

Skylight: means a window which is installed in a roof to permit natural light to enter the room below and is at an angle between 0 and 70 degrees measured from the horizontal plane.

Solar collector area: means the area of the flat panels of a solar hot water system that are exposed to the sun.

Solar hot water system: means a solar hot water system which is rated under the Renewable Energy (Electricity) Regulations 2001.

Solar powered: in relation to common area lighting, means external lighting (irrespective of the type of light bulb) that is powered directly by photovoltaics and is not connected to the mains electricity supply.

Strata Title: means a form of ownership devised for dwellings with shared areas such as residential flat buildings, multi-dwelling houses and dual occupancies.

Stand-by function: in relation to a sauna efficiency measure, means a function ensuring that where a system is not in use it reverts to an energy saving mode.

Storage: in relation to hot water systems, means a hot water system where water is heated and stored in an insulated tank.

Storey: means a space within a building that is situated between one floor level and the floor level next above, or if there is no floor above, the ceiling or roof above, but does not include: (a) a space that contains only a lift shaft, stairway or meter room, (b) a mezzanine, (c) a non-habitable attic storage space, or (d) lower level garage, workshop or store room.

Stormwater: means water collected from trafficable surfaces, including paved or ground surfaces.

Sub-division: means the division of land into parts for separate occupation, either as separate lots or strata lots.


Thermal Comfort Protocol: means the document of that name that establishes the requirements for using software to complete the Thermal Comfort index of a BASIX assessment by the simulation method.

Time clock: in relation to common area lighting and ventilation systems, means a control measure which switches a system off/on automatically at set times. 


Unconditioned floor area: in relation to a dwelling, means the total floor area of all bathrooms (not including ensuites) and laundries, with a ventilation opening.

Unit: means a dwelling which has one or more dwellings or buildings (excluding a garage or carpark) above or below it, such as a flat, unit or apartment.

Unit building: means a building containing one or more units.


Variable Speed Drive (VSD) fan: means a fan whose speed and therefore power consumption varies to suit the conditions at hand.

Ventilation exhaust: in relation to a ventilation system, means a system which expels air from a room or building.

Ventilation opening: means an opening in the external wall, floor or roof of a building, room or area, designed to allow air movement into or out of the building, room or area by natural means, including a door (but only a door which opens onto private open space), window, or other device which can be held open.

Ventilation supply: in relation to a system, means a system which draws fresh air into a room or building from outside it.

Ventilation system: means a system to refresh the air inside a building with air from outside the building.


Water meter: means a device used to monitor water use.

Well ventilated: in relation to refrigerator spaces, means that at least one side or the top of the refrigerator space is completely open.


Zoned switching: means switching which allows lighting to be individually turned off/on in two or more areas, rather than having one switch to light all areas.

Last updated: 14/09/2022