This guide serves to both define and explain the range of material properties that are used within this site and the web applications it provides. The aim is to establish a common reference so that important points and concepts do not need to be continually reiterated in multiple locations, but can be made within the property definition that they pertain most to.
Material properties come in two main types, those that describe the behaviour of a material or element when things impact upon or pass through it, and those describing any emissions from a material or element out into surrounding spaces. This guide considers both.
In this guide only material instance properties are listed. These are basically the ones whose name ends with ‘ance’ as opposed to ‘ivity’. Whilst not entirely universal, the convention is that terms such as resistivity, transmissivity, conductivity, reflectivity and absorptivity all refer to properties of a particular type of material and are given as values per unit of thickness or size. On the other hand, terms such as resistance, transmittance, conductance, reflectance and absorptance all refer to actual measured or calculated values from a specific instance or sample of a material which has a known thickness or size. Thus, if you know either value and the thickness or size of your test material, then you can easily derive the other value.
Where appropriate, material type version of those properties, which end in ‘ivity’ are discussed within the corresponding ‘ance’ definintion.
The behaviour of a material or building element describes what happens when things like air, heat, light, moisture vapour or sound impact upon its surfaces or pass over, through or around it.
Properties affecting the flow of air over, through or around a material or aperture.
Properties affecting the flow of heat through a material or aperture.
- Thermal Conductance
- Thermal Resistance
- Thermal Response
Properties affecting how light reflects, is absorbed or passes through a material or aperture.
- Refractive Index
- Light Reflectance
- Light Transmittance
- Light Absorptance
Properties affecting the flow of moisture vapour through a material or aperture.
Properties affecting how solar radiation reflects, is absorbed or passes through a material or aperture.
Properties affecting how sound reflects, is absorbed or passes through a material or aperture.
Properties affecting the visual presentation of a material.
Emissions refer to any heat, light, sound or off-gassing that occurs from a material or building element. These properties are usually applied to elements such as appliances, mechanical equipment, lights, speakers and even people who occupy the building.
Metrics for quantifying off-gassing from materials, appliances or equipment.
The different types of heat output by appliances or equipment.
Light and Radiation
Metrics for the amount of light output or radiant emissions by lamps, luminaires, appliances or equipment.
- Light Levels
- Low Frequency EMF
Metrics for the amount of sound emitted by appliances, equipment or speakers.