Material Definitions

Carbon

Carbon Footprint: The total amount of greenhouse gases produced to directly and indirectly support human activities, usually expressed in equivalent tons of carbon dioxide (CO2).

Carbon Neutral: Achieving net-zero carbon dioxide emissions by balancing the amount of carbon released with an equivalent amount sequestered or offset.

Carbon Offset: A way to compensate for emissions by funding an equivalent carbon dioxide saving elsewhere.

Carbon Sequestration: The process of capturing and storing atmospheric carbon dioxide. It is one method of reducing the amount of carbon dioxide in the atmosphere with the goal of mitigating global climate change.

Cradle to Cradle: This design philosophy argues for the transformation of industry through ecologically intelligent design. Products should be conceived from the outset in such a way that, at the end of their life, they can be broken down and their components reused or safely returned to the environment.

Cradle to Gate: This partial lifecycle assessment considers impacts from material production up to the factory gate before it is transported to the customer. This often includes upfront carbon emissions.

Cradle to Grave: This lifecycle assessment includes all stages from the extraction of raw materials (the "cradle") through to disposal (the "grave"). This methodology captures both upfront and operational carbon emissions.

Decarbonization: The process of reducing the economy's carbon intensity, including both operational and embodied or upfront carbon emissions.

Embodied Carbon: Also known as "embedded carbon", it refers to the carbon emissions associated with the non-operational phase of a product or service, such as manufacturing, transportation, and disposal. Embodied carbon is a part of upfront carbon.

Embodied Carbon: Carbon emissions associated with materials and construction processes throughout the whole lifecycle of a building. This includes Upfront Carbon, Use Stage Embodied Carbon, and End of Life Carbon, but not Operational Carbon.

End of Life Carbon: The carbon emissions associated with deconstruction/demolition, transport from the site, waste processing, and disposal phases of a building's lifecycle which occur after its use (Modules C1 to C4).

Green Star Project Scope: All areas and activities in a project that have been registered for Green Star. This includes all buildings and ancillary areas such as parking, landscaping, and shared facilities.

Life Cycle Analysis (LCA): This is a methodology for assessing environmental impacts associated with all the life cycle stages of a commercial product, process, or service.

Net-Zero Carbon Building: A building that is highly energy efficient and fully powered from on-site and/or off-site renewable energy sources, minimizing both operational and embodied carbon over the life of the building.

Operational Carbon: This refers to the carbon emissions that occur during a product or service's use or operation phase. This is in contrast to embodied or upfront carbon.

Operational Carbon: The emissions associated with energy used to operate the building (Module B6). Operational water (Module B7) is often included as part of Operational Carbon.

Proposed Project – Upfront Carbon: The building works to be rated by the Green Star Buildings rating tool, as designed and modelled by the project team as defined by the Green Star project scope.

Reference Project – Upfront Carbon: A hypothetical project of the same size, shape, location, floor area, and glazing areas as the Proposed Project.

Upfront Carbon Emissions: This term specifically refers to the emissions released during the extraction, manufacture, and delivery of a product or building materials before they are used or installed. It also refers to the carbon emissions caused before the building begins to be used, i.e., during the manufacture of building products, transport of building products to the site, and construction of the building (EN 15978 Modules A1 to A5).

Use Stage Embodied Carbon: Emissions associated with materials and processes needed to maintain the building during use such as for maintenance, repair, or refurbishments (EN 15978 Modules B1 to B5).

Materials

Capillary action: The movement of water through the pores of a material due to surface tension, affecting its hygrothermal performance.

Combustibility: The measure of how easily a material can ignite and sustain combustion.

Conductivity (thermal): The ability of a material to conduct heat, often measured in watts per meter-kelvin (W/m·K). Typical values range from 0.02 W/m·K for insulating materials to over 400 W/m·K for metals like copper.

Embodied carbon: The total greenhouse gas emissions associated with the extraction, production, transportation, and disposal of a building material, expressed in units of CO2 equivalent per unit mass or volume.

Emissivity (thermal): The effectiveness of a material's surface in emitting energy as thermal radiation. Values range from 0 (no emission) to 1 (perfect emitter).

Fire performance: A general term that encompasses various fire-related properties, such as fire resistance, flame spread, and smoke development.

Fire propagation index: A measure of the contribution of a material's surface to the growth of fire, taking into account both flame spread and heat release.

Fire resistance: The ability of a material or assembly to maintain its structural integrity and/or insulating properties when exposed to fire for a specified period.

Flame spread index (FSI): A rating that quantifies the surface burning characteristics of a material, with lower values indicating slower flame spread. Values typically range from 0 to 200, with lower values indicating better performance.

Hygroscopicity: The ability of a material to absorb moisture from the surrounding environment, influencing its hygrothermal behavior.

Impact insulation class (IIC): A rating that measures the effectiveness of a material or assembly in reducing impact sound transmission, such as footfall noise. Higher values indicate better performance, typically ranging from 25 to 60 or higher.

Moisture content: The amount of water present in a material, which can affect its thermal and hygrothermal properties.

Noise reduction coefficient (NRC): A scalar representation of a material's sound absorption properties, ranging from 0 (perfectly reflective) to 1 (perfectly absorptive).

Reflectance (solar): The proportion of incident solar radiation that is reflected by a material's surface, affecting its thermal performance.

Smoke developed index (SDI): A rating that quantifies the amount of smoke generated by a material during combustion, with lower values indicating less smoke production. Values typically range from 0 to 450 or higher, with lower values indicating better performance.

Solar heat gain coefficient (SHGC): The fraction of incident solar radiation that is transmitted through a material as heat, affecting the energy performance of buildings. Values range from 0 (no transmission) to 1 (all incident radiation transmitted).

Sound absorption: The ability of a material to absorb sound energy, reducing noise levels and improving acoustics within a space.

Sound transmission class (STC): A rating that measures the effectiveness of a material or assembly in reducing airborne sound transmission. Higher values indicate better performance, typically ranging from 25 to 60 or higher.

Specific heat capacity: The amount of heat required to change the temperature of a unit mass of a material by one degree Celsius, typically measured in joules per kilogram-kelvin (J/kg·K). Values range widely depending on the material, from about 400 J/kg·K for metals to over 2000 J/kg·K for some insulating materials.

Thermal diffusivity: The rate at which heat is conducted through a material relative to its heat capacity, calculated as the ratio of thermal conductivity to the product of density and specific heat capacity.

Thermal expansion: The increase in a material's size due to temperature changes, often characterized by the coefficient of linear expansion, which is typically expressed in units of strain per degree Celsius (1/°C). Values vary widely depending on the material, from near zero for some ceramics to over 20x10^-6 1/°C for metals like aluminum.

Thermal mass: The ability of a material to absorb and store heat energy, which can help moderate indoor temperature fluctuations. Materials with high specific heat capacity and density, such as concrete and brick, typically have good thermal mass.

Thermal resistance (R-value): The measure of a material's resistance to heat flow, with higher values indicating better insulating properties. R-value is typically expressed in square meter-kelvin per watt (m²·K/W) and varies depending on the material and its thickness. Insulating materials can have R-values in the range of 1-10 m²·K/W or higher.

Water vapor permeability: The ability of a material to allow the passage of water vapor, which influences the hygrothermal performance of building envelopes. It is typically expressed in nanograms per Pascal-second-meter (ng/Pa·s·m), with values ranging from less than 1 for vapor barriers to over 1000 for highly permeable materials like wood.

Daylight

Ambient Calculation: A calculation in Radiance to simulate diffuse interreflection of light between surfaces.

Annual Sunlight Exposure (ASE): This metric measures the potential for excessive sunlight and the risk of glare, calculated as the percentage of the annual occupied period that a specific point in a space exceeds a certain illumination level due only to direct sunlight.

Daylight Autonomy (DA): This metric calculates the percentage of an annual occupied period when a specific point in a space is above a certain illumination level, due only to natural light.

Daylight Factor (DF): This is a standard metric used in daylight design. It expresses the percentage of daylight available inside, compared to the amount of daylight available outside, under overcast sky conditions.

Daylight Glare Probability (DGP): This is a metric used to predict the probability of glare from daylight in an interior space.

Daylight Harvesting: The use of control systems and scheduling to switch or dim electric lighting in response to changes in daylight availability.

Daylight Sensor: A device typically used in lighting control systems to measure the amount of daylight in a space.

Direct and Indirect Illumination: Radiance calculates both the direct component of light from light sources and the sky, and the indirect component from interreflections.

Externally Reflected Component: The part of the daylight factor representing light reflected from external surfaces into the room.

Falsecolor Image: A post-processing technique in Radiance to visualize illuminance or luminance levels in an image.

Foot-candle: This is a non-SI illuminance or light intensity unit widely used in the United States. One foot-candle is equal to one lumen per square foot.

Illuminance: This is the amount of light level measured on a surface area. It is typically expressed in foot-candles (fc) in the US or lux in the metric system.

Light Sources: Definitions of the intensity and color of light emitted by luminaires or the sky in a Radiance model.

Lux: This is the SI unit of illuminance, measuring luminous flux per unit area. One lux is equal to one lumen per square meter.

Luminance: This is the amount of light that a surface emits, reflects, or transmits. Unlike illuminance, which is a measure of incident light, luminance describes the light leaving a surface in a particular direction.

Materials: In Radiance, these are the definitions of surface light-reflecting and transmitting properties.

Numerical Output: Radiance can also produce numerical data for illuminance or luminance at points in a model.

Photon Map: A technique used in conjunction with ray tracing to simulate global illumination in complex scenes.

Pictorial Rendering: The creation of a visually realistic image of a model in Radiance.

Radiance (unit): A radiometric unit of measure that describes the amount of light that passes through or is emitted from a particular area and falls within a given solid angle. It's used in Radiance software to simulate light behaviour.

Radiances per Pixel (RPP): A rendering parameter controlling the quality and speed of the rendering.

Ray-tracing: Radiance uses a method to trace the path of light as pixels and simulate complex light interactions in 3D environments.

Rendering Parameters: The settings in Radiance that affect the quality and computational requirements of the simulation.

Scene Geometry: The 3D definition of objects and spaces in a Radiance model.

Sky Component: The part of the daylight factor that represents the contribution of the clear sky.

Sky Model: Radiance includes several models to simulate the sky, including CIE standard overcast and clear skies and the Perez all-weather model.

Specularity: The mirror-like quality of a surface in a Radiance material definition.

Transmissivity: The property of a surface material that determines how much light is transmitted through it in a Radiance model.

Useful Daylight Illuminance (UDI): This metric combines the concepts of Daylight Autonomy and Glare to measure the time a space receives the ideal illumination level, not too little or too much.