Activity that leads to a reduction in the level of greenhouse gas emissions.


A structure built to support the lateral pressure of an arch or span, for example at the ends of a bridge.


Software tool used in rating the thermal performance of homes in Australia. Designed by the CSIRO, based on decades of scientific research about the way buildings operate in Australian conditions, AccuRate is accredited for use under the Nationwide House Energy Rating Scheme (NatHERS). Accurate is used as the NatHERS benchmark against which the performance of other software tools is assessed.

Acid sulfate soil

Soil that contains iron sulfides, which when exposed to oxygen by drainage or disturbance, produce sulfuric acid, and often release toxic quantities of iron, aluminium and heavy metals.


A term for any particulate material. It includes gravel, crushed stone, sand, slag, recycled concrete and geosynthetic aggregates. Aggregate may be natural, manufactured or recycled.


A transitional space that typically has 2 doors in series to separate a controlled internal environment from external environments.


The level of uncontrolled movement of air in to and out of a building. Measured as the air tightness metric (air changes per hour at 50 pascals; ACH50).

Air tightness

The level of uncontrolled movement of air in to and out of a building. Measured as the air tightness metric (ACH50)

Angle of incidence

In relation to windows, the angle that solar radiation strikes glass. When the sun is perpendicular to the glass it has an angle of incidence of 0°. As the angle increases, the effective area of exposure to solar radiation reduces, more solar radiation is reflected, and less is transmitted.


Person qualified and/or accredited to use energy rating tools (for example, NatHERS tools) to determine the thermal performance of a building.

Autoclaved aerated concrete (AAC)

Concrete that has been manufactured to contain lots of closed air pockets. Lightweight and fairly energy efficient, it is made by adding a foaming agent to concrete in a mould, then wire-cutting blocks or panels from the resulting ‘cake’ and ‘cooking’ them with steam (autoclaving).


Software tool used in rating the thermal performance of homes in Australia. BERS Pro is accredited for use under NatHERS.


The variety of all life, including plants, animals, microorganisms, the genes they contain, and the ecosystems of which they form a part.


Water that has been mixed with waste from the toilet.


The extent to which the design of a building facilitates ease of construction.

Building Code of Australia (BCA)

Contains technical provisions for the design and construction of buildings and other structures in Australia. It comprises Volumes 1 and 2 of the National Construction Code (NCC). It is maintained by the Australian Building Codes Board on behalf of the Australian Government and state and territory governments.

Building envelope

A building’s walls, roof, ceilings and floors that separate the interior of the building from the outside air and elements.

Building Sustainability Index (BASIX)

A measure of a building’s water and energy consumption and thermal comfort. BASIX is part of the development application process in New South Wales and applies to all new residential dwelling types and large renovations.


A rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. A cantilever can be formed as a beam, plate, truss, or slab.

Carbon dioxide equivalent (CO2-e)

A standard measure that is used to compare the emissions from various greenhouse gases on the basis of their global warming potential. It allows a common metric to be used across all gases by converting them to an equivalent amount of carbon dioxide with the same global warming potential.

Carbon offsetting

A process that removes greenhouse gases or averts their emission into the atmosphere and stores or ‘sequesters’ them for periods of varying duration. Carbon offsets are usually purchased by individuals or companies and used to ‘offset’ the emissions they generate.

Carbon positive

Describes buildings that go beyond achieving net zero carbon emissions to produce more renewable energy on site than the building requires, and feeds excess renewable energy back into the grid.

Cementitious material

Describes materials that make up the concrete mixture.

Chlorofluorocarbons (CFCs)

A class of refrigerants that have a very high global warming potential.


The non-loadbearing skin or layer attached to the outside of a home to shed water and protect the building from the effects of weather.

Clerestory window

High windows that can deliver daylight into a space.

Climate change

Increased greenhouse gas emissions across the globe are causing changes to the composition of Earth’s atmosphere. This in turn, is causing warming and changes to the global climate system.


Production of 2 forms of energy (electricity and useful heat) from the same process. Also can be known as ‘trigeneration’.

Cold cathode fluorescent lamp (CCFL)

A lamp that uses a discharge in mercury vapour to develop ultraviolet light, which in turn causes a fluorescent coating on the inside of the lamp to emit visible light.

Compact fluorescent lamp (CFL)

Lamp using a fluorescent light bulb that has been compressed into the size of a standard-issue incandescent light bulb.

Compressive strength

The ability of a material to resist breaking under compression.


The transfer of heat from one substance to another by direct contact.

Conductive loss or gain

Loss or gain of heat directly through contact with a person, object or floor.


Heat transfer in a gas or liquid by the circulation of currents from one region to another.

Convective heating

A process using the natural circulation of air across a heat source to warm a space.

Cross-through or cross-over apartments

Apartments on 1 or 2 levels with 2 opposite aspects.

Cross ventilation

Cross ventilation (also called wind effect ventilation) is a natural method of cooling. The system relies on wind to force cool exterior air into the building through an inlet (like a louvre, or an open window) while an outlet forces warm interior air outside (through a roof vent or higher window opening).


Loose natural material such as leaf litter, sticks, rocks and soil.

Demand response

The voluntary reduction or shift of electricity use by a consumer, which can help to stabilise the power grid. Typically involves paying energy consumers to cut or shift their use of electricity demand to match supply.

Dew point

The temperature to which air must be cooled to become saturated with water vapour, and condense to form liquid (dew).

Direct emissions

Emissions produced from sources within the boundaries of a building (for example, burning of natural gas in water and space heaters).


Relating to the daytime, or during the day.


A measure of formaldehyde emission from plywood and other timber products. The lowest rating, Super E0, has the fewest emissions.

Earth bermed

The practice of using earth against building walls for external thermal mass, to reduce heat loss, and to easily maintain a steady indoor air temperature. Also known as ‘earth-covered’ house.

Earth-coupled slab

A slab-on-ground has greater thermal mass due to direct contact with the ground. This is known as earth coupling. Deeper, more stable ground temperatures rise beneath the house, passing temperatures into the slab.

Earth render

A mud or clay slurry, which may be reinforced with straw or cow dung, applied to mud brick or cob walls, or applied to a straw bale wall


An easement is a property right to use another person’s land for a stated purpose.

Ecological carrying capacity

The maximum population size of a species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.


An international database developed in Australia detailing certified and verified sustainable products (

Embodied emissions

The greenhouse gas emissions caused directly or indirectly from the production of embodied energy.

Embodied energy

The sum of all energy used to extract, transport, manufacture and construct a building, as well as the services used in the economy that support these processes.

Energy efficient

Using less energy to perform the same task.

Energy Rating Label

An Australian Government scheme that assigns star ratings to a range of appliances. The star rating gives a comparative assessment of the appliance’s energy efficiency and comparative energy consumption over a year.

Environmental Certification Scheme (ECS)

An environmental labelling scheme for textile floor coverings, administered by the Carpet Institute of Australia.


The process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants.

Expanded polystyrene (EPS) or extruded polystyrene (XPS)

Rigid plastic foam insulation that provides high insulation values and has a closed cell structure that limits moisture. EPS has pollution problems because small particles break off and can escape into the local environment. Other options are polyisocyanurate (PIR) and polyurethane (PUR) foam.


A substance added to cement either to reduce cost or carbon emissions, or modify its properties to some extent.


Exterior of the house.


Long board that is fixed vertically underneath the overhang of the roof, to carry the guttering.

Ferrous material

Containing iron.


Software tool developed by the Victorian Government and used in rating the thermal performance of homes in Australia. FirstRate is accredited for use under NatHERS.

Fixed appliances and equipment

Appliances, equipment, and associated systems that are fixed in place, have dedicated connections to the building’s energy or water supply and would normally not be moved from the building on change of ownership or lease.


A strip of metal used to stop water penetrating the junction of a roof with another surface.

Fly ash

Fine grey powder that is produced as a by-product in coal fired power stations and used as an extender in concrete products.


A structure, usually temporary, that is used to mould poured concrete, rammed earth or other materials into required dimensions until it is dry and able to support itself.


Inorganic polymers, with superior mechanical and physical properties, for uses such as fire- and heat-resistant coatings and new cementitious materials for concrete.


Permeable fabrics that, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain.

Geothermal heat pump

A pump that uses the natural heat of the earth or groundwater to heat and cool a building.

Glass wool

An insulating material made from fibres of glass and formed into a texture similar to wool.

Glued laminated timber (glulam)

A type of structural engineered wood product constituted by layers of dimensional lumber bonded together.

Green roof or wall

Roof or wall that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane or attached to a framework. Also known as ‘living roof or wall’.

Green Star — Communities

A rating tool that defines best practice benchmarks in 5 sustainability categories for the planning, design, and delivery of sustainable communities.

Green Tick®

Symbol used to identify a product or service that has been independently certified as environmentally sustainable. Developed in New Zealand in 2004.

Green Tick (furniture)

Certification program developed by Furntech-Australasian Furnishing Research and Development Institute, to confirm that a piece of furniture meets a robust yet realistic level of sustainability requirements.

Greenhouse gases

The atmospheric gases responsible for causing climate change. The major greenhouse gases are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).


An Australian Government accreditation program that sets environmental and reporting standards for renewable electricity products offered by energy suppliers to households and businesses.


Wastewater from non-toilet plumbing fixtures such as showers, basins and taps.


The network of wires, substations, transformers and switches that carry electricity from the generator to the consumer.


A ring or edge strip, often made of metal, plastic, or rubber, inserted into a hole usually to protect the material that is passing through the hole.

Header tank

A raised tank that maintains a constant pressure or supply to a system, especially the small tank that supplies water to a central heating system.

Heat exchanger

A device used to transfer heat from fluid or air on one side of a barrier to fluid or air on the other side without bringing them into direct contact.

Heat island effect

Where built-up urban areas become hotter due to the absence of shade trees and heat reflected from buildings, concrete pavements and transport.


Software tool used in rating the thermal performance of homes in Australia. HERO is accredited for use under NatHERS.

High mass construction

A building constructed with high thermal mass, such as masonry or adobe.


Hydrology is the science that encompasses the study of water on the Earth's surface and beneath the surface of the Earth.

Hydronic system

A system that circulates hot water or coolant through radiator panels in rooms, supplying a mix of convective and radiant heat. Hydronic systems are usually gas fired but can be heated by a wood fired heater, solar PV system or heat pump.

Indigenous (plants)

Native flora that occurs naturally in an area.

Indirect emissions

Emissions generated elsewhere as a consequence of energy use in a building, for example, emissions produced by a coal-fired power station.

In-home display

A dedicated display device designed to deliver energy-related information such as energy consumption, pricing or service messages from a utility or third-party energy service provider to a residential customer.

Insulated glass unit

Combination of 2 or more glazing layers sealed with a gap between the layers.


An electrical system that converts direct current (DC) into alternating current (AC).


A length of timber or steel supporting part of the structure of a building, typically arranged in parallel series to support a floor or ceiling.


Thermal insulation for wrapping around pipes or boilers.


Any liquid that, in passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed.

Lifecycle assessment

Measurement of the total environmental impact of a material or product through every step of its life from obtaining raw materials to manufacture, transport, storage, use, and disposal or recycling/reuse.

Lifecycle costing

A method of economic analysis that takes into account expected costs over the useful life of an asset.

Light-emitting diode (LED)

A form of lighting that illuminates not through a filament but through the movement of electrons in a semiconductor material.

Lightweight construction

A building construction approach using building materials that have low thermal mass, such as timber, plaster and render, and masonry less than 70mm thick. Also known as ‘low mass construction’.


A horizontal support of timber, stone, concrete, or steel across the top of a door or window.

Liveable house

A house that uses a combination of building features, fittings and products to meet the changing needs of home occupants throughout their lifetime.

Living Building Challenge

A philosophy, advocacy tool, and certification program that promotes an advanced measurement of sustainability in the built environment.

Local generation

The production of electricity from a generator attached to a building or a nearby site. Also known as ‘on site’, ‘distributed’, or ‘embedded’ generation.

Low emissivity (low e) glass

Glass that transmits less thermal energy (that is, heat).

Low-emission energy

Energy that has been generated with significantly fewer emissions than average grid-supplied energy.

Low thermal emissivity

Low emissivity (low e or low thermal emissivity) refers to a surface condition that emits low levels of radiant thermal (heat) energy.


A complete light fitting where the LED light source is combined with the light fitting.

Minimum Energy Performance Standard (MEPS)

A minimum efficiency standard that must be achieved by all appliances belonging to a particular group (for example, fridges). MEPS is a specific requirement under the Greenhouse and Energy Minimum Standards Act 2012 (GEMS Act).

National Australian Built Environment Rating System (NABERS)

A system to measure the environmental performance of Australian commercial buildings. It does this by using measured and verified performance information, such as utility bills, and converting them into a star rating scale from 1 to 6 stars.

National Construction Code (NCC)

A performance-based code that sets the minimum requirements for buildings in Australia in relation to structure, fire safety, access and egress, accessibility, health and amenity, and thermal performance. All new buildings, new building work, and new plumbing and drainage systems must comply with the NCC.

Nationwide House Energy Rating Scheme (NatHERS)

Administered by the Commonwealth, NatHERS rates the thermal performance of homes in Australia. These ratings can be used to meet the minimum energy efficiency requirements for homes and major renovations in the National Construction Code. See

NatHERS stars

A star rating system used to score the thermal performance of a home, ranging from 0 to 10 stars. The ratings are based on software calculations considering a large number of variables including dwelling size, materials, orientation, type and placement of windows and climate zone.

Natural aggregates

Manufactured crushed stone and sand created by crushing bedrock, or naturally occurring unconsolidated sand and gravel.

Nature strip

The grass strip in front of a house between a fence or footpath and a roadway. Also known as ‘street verge’.

Night purging

A highly effective method of pre-cooling a building or room during the night, before it is occupied again the next day. It involves operable windows or louvres being opened for a period overnight, allowing natural air flow to remove unwanted heat.


A strut used to give rigidity to a framework, typically fixed between joists or studs to increase their strength or stiffness. Noggins are commonly used to brace floors or to stiffen timber stud frames.

North (true and magnetic)

True north is a fixed point on the Earth’s surface. Magnetic north varies in position due to the movement of molten metal below the Earth’s crust.

Off-form concrete

Concrete or another material that has been cast against formwork (see ‘formwork’). The finished product takes on the texture of the surface it is cast against.

Off-form finishes

This is the surface finish obtained when concrete or another material is removed from formwork or a mould. The texture and shape of the mould provide the surface finish.

Off-peak tariff

A cheaper tariff offered by electricity providers to consumers who agree to have limits placed on when their water heaters or other devices can operate.

Operational energy

Energy consumed during a building’s operational life, such as heating, cooling or appliances.

Organochlorine pesticides

Insecticides (for example, chlordane and dieldrin) previously used to control insects such as termites in houses. Their use in Australia was banned in the late 1980s due to health and environmental concerns.


Positioning of a building and living spaces in relation to seasonal variation in the sun’s path and to prevailing wind patterns.


A barrier that is an extension of the wall at the edge of a roof, terrace, balcony, walkway or other structure.

Passive cooling

Design features or technologies used to cool buildings without power consumption.

Passive design

Design that takes advantage of the climate to maintain a comfortable temperature range in the home with minimal or no artificial heating or cooling.

Passive heating

A system of features incorporated into a building’s design to use and maximise the effects of the sun’s natural heating capability.

Peak demand

The maximum energy demand in a given location over a given time, often driven by increased cooling or heating loads due to temperature extremes.

Phase-change material (PCM)

A substance that is capable of storing and releasing heat. Heat is absorbed or released when the material changes from solid to liquid and vice versa.


A method of generating electrical power by converting solar radiation into direct current (DC) electricity.


Building material of stiff clay or earth, forced between boards which are removed as it hardens (see also ‘rammed earth’).

Polyisocyanurate (PIR) and polyurethane (PUR)

Forms of rigid plastic foam insulation that provide high insulation values and have a dense closed cell structure that limits excessive moisture.

Prefabricated construction (prefab)

Large components of the building are constructed in a factory before being assembled onsite.

Radial symmetry

A balanced arrangement of similar radiating parts arranged around a central axis.


Transfer of heat through thermal emission. See also ‘Conduction’ and ‘Convection’.

Rammed earth

A mixture of sand, loam, clay, and other ingredients rammed hard within forms as a building material.

Rating tool

A tool or procedure that uses predefined data relevant to the dwelling and converts this data into a rating outcome using algorithms and assumptions built into the tool.

Reactive soil

Any type of soil that, when exposed to certain physical or geological conditions, will undergo changes in shape and structure.

Renewable energy

Energy that is derived from sources that are renewed by natural processes, for example, solar energy, hydropower, wind, tide, geothermal, and biomass.


To furnish or install new or modified parts or equipment into a building.

R value

A measure of resistance to the flow of heat through a given thickness of a material (for example - insulation) with higher numbers indicating better insulating properties.


A membrane located beneath tiles or other roofing to assist insulation to work more efficiently and to prevent condensation re-entry. The membrane may be either reflective or non-reflective, and either permeable or non-permeable.

Skillion roof

A sloping roof surface. Sometimes called a shed-style or lean-to roof.

Small-scale technology certificate (STC)

A tradeable commodity attached to eligible installations of renewable energy systems, including solar panels, solar water heaters and heat pumps.

Smart appliance

A product that has the capability to adjust its operation based on a signal received from a utility, third party energy provider or home energy management device.

Smart Approved WaterMark

Australia’s water conservation label, which identifies and promotes products and services that help save water.

Smart grid

An electrical grid that gathers information such as the behaviour of suppliers and consumers, to improve the efficiency, reliability and distribution of electricity.

Smart home

Automation of the home to provide improved convenience, comfort, energy efficiency and security; may include centralised control of household appliances and technology such as lighting, heating or security systems.

Smart meter

An electrical meter that records consumption of electricity and communicates real-time data to the household and the utility for monitoring and billing purposes.


A trench or cavity dug into the ground and connected to the downpipe from a roof, allowing rainwater to seep into the earth rather than flood near the house.


The underside of a structure such as an arch, a balcony, or overhanging eaves.

Solar heat gain coefficient (SHGC)

The fraction of solar radiation that enters a building as heat gain through windows, glass doors or skylights. SHGC is expressed as a number between 0 and 1. The lower a glazing unit’s SHGC, the less solar heat it transmits.

Stack ventilation

The upward movement of air through openings in a building fabric due to thermal buoyancy and/or negative pressure generated by the wind over the roof.


All rain that falls on the roof or land, plus anything it carries with it as it drains off the site.

Strip footings

Standard rectangular, reinforced concrete footings typically positioned under loadbearing or masonry walls where lightweight floor framing is used.

Structural insulated panel (SIP)

An insulation layer of rigid foam material sandwiched between 2 structural skins of sheet metal, plywood, fibre cement or engineered timber.


A rod or bar forming part of a framework and designed to resist compression.


An underlying substance or layer.

Temperature differential (ΔT)

The difference in temperature between different areas (for example, wall, floor, ceiling, window). The greater the temperature differential, the greater the heat flow through the element.


If a material is tensile, it can be stretched. Tensile strength relates to resistance to structural failure under tension.


A force that tends to stretch or elongate a material.

Thermal bridging

When a conductive (or poorly insulated) material allows heat flow across a thermal barrier.

Thermal comfort

A person’s subjective feeling of how comfortable the surrounding temperature is.

Thermal lag

The rate at which a material releases stored heat. The higher the thermal mass in most common building materials, the longer the thermal lag.

Thermal mass

The ability of a material to absorb, store, and release heat.

Thermal performance

The effectiveness of a building envelope in maintaining acceptable levels of human comfort in the building relative to the outside weather conditions while minimising the need for artificial heating or cooling.


A method of passive heat exchange based on natural convection which circulates a substance (liquid or gas such as air) without the need for a mechanical pump.


A type of construction technique using concrete panels that are "tilted" to the vertical position with a crane and braced into position until the remaining structural components are secured.

Time-of-use pricing

In electricity supply, a pricing method in which electricity has different prices based on the time of use. Also called ‘differential’, ‘time-variant’ or ‘flexible’ pricing.


A window above a door.

Trickle vent

A very small opening in a window or other building envelope component to allow small amounts of ventilation.


A framework (for example, of rafters or struts) supporting a roof.

U value

A measure of heat loss in a building element, which demonstrates how well it transfers heat. The lower the U value, the better the insulating ability. Expressed as Uw in windows.

Vapour barrier

The function of a vapour barrier is to control the flow of air and water vapour through the building structure.

Visible light transmittance (VLT)

In window glass, the amount of visible light that is transmitted. A low VLT can reduce heat gain from the sun, but if it is too low, it will be dark inside the room.

Volatile organic compounds (VOCs)

VOCs are emitted as gases from certain solids or liquids, some of which are a potential health hazard.

Volume builder

Large companies that perform large amounts of building work. Volume builders often promote their service based on price and offer a fixed range of 'display home' models.

Waffle pod

A type of slab constructed entirely above the ground by pouring concrete over a grid of polystyrene or recycled plastic blocks known as ‘void forms’.

Water Efficiency Labelling and Standards (WELS) scheme

A scheme that requires certain products to be registered and labelled with their water efficiency in accordance with the standard set by the Water Efficiency Labelling and Standards Act 2005.

Water-sensitive urban design (WSUD)

The integration of stormwater management and sediment control into urban planning and design.

Water table

Upper level of underground soil and rocks permanently saturated with water.

Weep hole

A hole in a concrete or brick wall or foundation that is designed to drain off accumulated water.

Weighted sound reduction index (Rw)

Metric used by the National Construction Code for indicating the effectiveness of a structure as a noise insulator.


Absorbing or drawing off liquid by capillary action.

Window Energy Rating Scheme (WERS)

A scheme that enables glazing units to be rated and labelled based on their solar, thermal and optical properties. WERS is managed by the Australian Glass and Window Association.

Zero carbon and zero energy

Applies to buildings that use renewable energy sources (usually on site) to generate energy for their operation, so that over a year the net amount of energy generated on site equals the net amount of energy required by the building.

Zero lot line

A zero-lot-line property is 1 where a home or building has at least one wall placed on the boundary line of the property.