materials library / attributes

NEURODESIGN® · 87 ATTRIBUTES · 14 FAMILIES

Attributes

Two groups. Material attributes describe what the thing is and how it behaves as matter. Sensory attributes describe what a person can actually perceive. They are held apart because the first group is what a manufacturer knows and the second group is what a designer is really choosing between, and almost no product documentation in the industry carries both.

Every attribute names the standard it is measured against. Where no standard exists, the entry says so in a dashed box. That is the most useful thing on this page: 10 attributes have no comparable measurement method, and they are concentrated in exactly the areas this field talks about most.

material attributes
51
sensory attributes
36
families
14
without a method
10

What cannot currently be measured

Tactile and olfactory perception carry most of this. Four of the six tactile attributes and one of the three olfactory ones have no standard method for interior surfaces, alongside translucency, pattern regularity and fractal dimension. Those last three are invoked constantly in writing about this subject and are almost never measured on a material anyone actually specified.

Material attributes 51

Composition 11

What the thing is made of. Almost every downstream property is a consequence of this layer, and almost every product page in the industry omits most of it.

  • Primary material classThe dominant constituent by mass, resolved to a class the research literature would recognise.controlled termManufacturer disclosure
  • Secondary materialsEverything else present above the residual threshold, including the parts that are not visible.controlled termsManufacturer disclosure
  • Binder systemWhat holds the material together. Frequently the source of emissions in an otherwise inert product.controlled termManufacturer disclosure
  • Backing or substrateThe layer bonded behind the wear surface. Decisive for acoustics and for end-of-life separability.controlled termManufacturer disclosure
  • Surface coatingApplied finish, sealer or wear layer. Governs gloss, cleanability and what the occupant actually touches.controlled termManufacturer disclosure
  • Dye or pigment systemColourant chemistry and method of application.controlled termManufacturer disclosure
  • Flame retardant additivePresent, absent, or undisclosed, with the chemical family where declared.controlled termManufacturer disclosure
  • Antimicrobial additivePresent, absent, or undisclosed. Recorded because the health claim attached to it is usually stronger than the evidence.controlled termManufacturer disclosure
  • PlasticiserChemical family where present, given the semi-volatile exposure route.controlled termManufacturer disclosure
  • Recycled contentPre- and post-consumer recycled fraction, reported separately.% by massISO 14021
  • Bio-based contentBiogenic carbon fraction. Not a synonym for natural, and not a health attribute.% by massASTM D6866

Disclosure 4

How much of the composition is actually known. Treated as an attribute in its own right, because a material with no disclosure is not a material with nothing to disclose.

  • Ingredient disclosure completenessThe share of the product, by mass, whose constituents are named to a residual threshold.% by mass disclosedHPD Open Standard
  • Residual disclosure thresholdThe concentration below which constituents are not reported. A 1000 ppm threshold and a 100 ppm threshold are not comparable disclosures.ppmHPD Open Standard
  • Red List statusFree, declared with exceptions, or not assessed.controlled termILFI Red List
  • Supply chain traceabilityHow far back the chain of custody is documented.controlled termScheme-dependent

Bulk physical 9

The properties that decide how a material behaves as a body of matter, before anyone looks at it or touches it.

  • Bulk densityMass per unit volume, including internal voids.kg/m3ISO 1183 / ASTM D792
  • ThicknessNominal and wear-layer thickness where these differ.mmProduct standard
  • Mass per unit areaThe figure that governs structural loading and, for absorbers, low-frequency behaviour.kg/m2Product standard
  • PorosityVoid fraction. The precondition for sound absorption in fibrous and open-cell materials.% void volumeASTM D6226 and equivalents
  • Airflow resistivityResistance to air movement through the material. The single physical property that most directly predicts porous absorption, and one almost never published on a product page.Pa.s/m2ISO 9053
  • Moisture absorptionEquilibrium moisture uptake.% by massISO 62 / ASTM D570
  • Water vapour permeabilityVapour transmission through the assembly.perm or ng/Pa.s.m2ASTM E96 / ISO 12572
  • Dimensional stabilityMovement under specified humidity and temperature change.% changeProduct standard
  • Open-cell fractionShare of cells connected to the surface, for foamed and cellular materials.%ASTM D6226

Mechanical 8

How the material resists the forces of occupation. Mostly a durability question, but hardness and compliance are also felt directly by the body.

  • Surface hardnessResistance to indentation. Three incompatible scales by material family, which is why cross-class hardness comparison is not offered.Shore / Janka N / MohsASTM D2240, ASTM D143, Mohs scale
  • Abrasion resistanceWear under standardised rubbing. Martindale for textiles, Taber for coatings, PEI for glazed tile.cycles or classISO 12947, ASTM D4060, ISO 10545-7
  • Tensile strengthForce to failure in tension.MPa or NProduct standard
  • Flexural strengthResistance to bending failure.MPaISO 10545-4 and equivalents
  • Impact resistanceEnergy absorbed before fracture or permanent marking.JProduct standard
  • Indentation recoveryRecovery from static and dynamic loading, for resilient and textile floor coverings.%ISO 3415 / ISO 3416
  • Dynamic coefficient of frictionSlip resistance under wet dynamic conditions.DCOFANSI A326.3
  • Tear strengthResistance to tear propagation, for sheet and textile materials.NProduct standard

Durability and maintenance 8

What the material becomes over a service life, and what has to be done to it in the meantime. Maintenance chemistry is an exposure route that material selection quietly determines.

  • Light fastnessColour retention under controlled light exposure.blue wool scale 1-8ISO 105-B02 / AATCC 16
  • Colour fastness to rubbingTransfer of colourant under dry and wet rubbing.grey scale 1-5ISO 105-X12
  • CleanabilityEase of soil removal. Manufacturer protocols are not comparable across products, which is recorded rather than smoothed over.classNo common standard
  • Chemical and stain resistanceResistance to specified reagents, including cleaning agents.classISO 10545-13 / ASTM D1308
  • Required maintenance chemistryWhat must be applied to keep the warranty. A low-emitting material maintained with a high-emitting product is a mixed exposure.controlled termManufacturer protocol
  • Expected service lifeReference service life as declared, with the assumed use intensity.yearsEPD reference service life
  • RepairabilityWhether damage can be made good in place, in units, or only by full replacement.controlled termAssessment
  • End-of-life routeDocumented take-back, recyclability, or landfill by default.controlled termAssessment

Fire 3

Regulatory before it is experiential, but it constrains the palette available to every other layer, and flame retardant chemistry is itself an exposure question.

  • Reaction to fire classClassification under the applicable regional method. The two systems are not interconvertible.Euroclass or Class A-CEN 13501-1 / ASTM E84
  • Critical radiant fluxFlooring-specific flame spread resistance.W/cm2ASTM E648 / NFPA 253
  • Smoke developmentSmoke produced under the test fire.indexASTM E84 / EN 13501-1

Emissions 8

The route by which a material reaches the occupant without being seen, heard or touched. The best-established health layer in the whole taxonomy, and the one where certification infrastructure is already mature.

  • TVOC emission rateTotal volatile organic compound concentration in a chamber at a stated loading and air change rate.ug/m3 at specified dayISO 16000-9 / CDPH Standard Method v1.2
  • Formaldehyde emissionFormaldehyde concentration under chamber conditions.ug/m3ISO 16000-3 / EN 717-1
  • Individual VOCs of concernNamed compounds reported individually rather than absorbed into a total.ug/m3CDPH Standard Method v1.2 CREL list
  • Semi-volatile organic compoundsPlasticisers, flame retardants and their relatives. Long-lived, partition to dust and surfaces, and largely outside current certification.ug/m3No consensus material method
  • Particle and fibre sheddingRelease of particulate from the surface under use and cleaning.no standard unitNo consensus material method
  • Added fragranceDeliberately added scent. An emission that is marketed rather than minimised.yes / no / undisclosedManufacturer disclosure
  • Microbial growth supportWhether the material supports fungal or bacterial growth under specified humidity.classISO 846 / ASTM G21
  • Test loading ratioSurface area per chamber volume assumed in the test. Results at different loading ratios are not comparable, and the ratio is often the difference between a pass and a fail.m2/m3Part of the emissions protocol

Sensory attributes 36

Visual: luminance and colour 7

How the surface handles light. The layer with the most mature measurement infrastructure and the most direct route into both circadian and perceptual literature.

  • Light reflectance valueShare of visible light reflected. Governs how much of a room's light survives its surfaces.% (0-100)ASTM E1477 / CIE Y
  • Specular glossMirror-like reflection at a standard angle.GU at 60 degreesASTM D523 / ISO 2813
  • Specular to diffuse ratioHow reflection is distributed between mirror direction and scatter. Determines whether a surface produces highlights or glow. Requires goniophotometry.ratioNo standard method
  • Lightness L*Perceptual lightness, distinct from reflectance in that it is scaled to human response.CIELAB L*CIE 15
  • Chroma C*Colour intensity independent of hue and lightness.CIELAB C*CIE 15
  • Hue angleHue position, held numerically so that palettes can be compared rather than described.CIELAB h degreesCIE 15
  • Spectral reflectance curveFull reflectance spectrum. Needed to predict how a surface behaves under a given light source, and how it shifts the spectrum of interreflected light.% per wavelengthSpectrophotometry, CIE 15

Visual: pattern and structure 7

The layer that most neuroarchitecture writing gestures at and almost nobody measures. Several of these attributes have no standard method at all, which is recorded here as a finding.

  • Pattern repeat scaleDistance over which the pattern repeats.mmProduct specification
  • Pattern regularityHow predictable the pattern is across the surface. Spatial autocorrelation is the usual research approach.indexNo standard method
  • Edge densityDensity of luminance edges at a stated viewing distance. Depends on installed distance, not on the sample.edges per degreeResearch technique
  • Fractal dimensionStatistical self-similarity across scales. Widely invoked in this field and rarely measured on actual specified materials.D (1.0-2.0)Box-counting, research technique
  • Batch variationColour difference between units or production runs.delta E 2000CIE ISO/CIE 11664-6
  • Within-surface contrastLuminance range across the surface itself.Michelson contrastImage analysis
  • Glare potentialContribution to discomfort glare. A property of the installed surface under a specific lighting layout, never of the sample.luminance ratioCIE 117, in situ

Visual: transmission 3

For materials that pass light rather than return it.

  • Total transmittanceShare of incident light transmitted.%ASTM E903 / ISO 9050
  • HazeShare of transmitted light scattered wide of the beam.%ASTM D1003
  • Visual translucencyPerceived depth of light penetration in stone, ceramic and resin. Consistently described in specification and never quantified.no standard unitNo standard method

Acoustic 6

The best-measured sensory layer after light, and the one where the mounting condition quietly decides the result.

  • Noise reduction coefficientArithmetic average of absorption at 250, 500, 1000 and 2000 Hz, rounded to the nearest 0.05. A summary, not a spectrum.0-1ASTM C423
  • Absorption coefficient by octave bandAbsorption across frequency. The figure that matters when the problem is speech intelligibility or low-frequency rumble rather than general liveliness.alpha per bandISO 354 / ASTM C423
  • Mounting conditionHow the sample was mounted in test. The same material can differ by several tenths of an absorption coefficient between mountings, and the mounting is routinely omitted from published figures.mounting typeASTM E795
  • Scattering coefficientShare of reflected sound diffused rather than returned specularly.0-1ISO 17497-1
  • Impact sound reductionImprovement in impact noise transmitted to the space below. The defining acoustic complaint in hotels.delta IIC or delta LwASTM E2179 / ISO 10140-3
  • Airborne sound reductionTransmission loss through the assembly.Rw or STCISO 10140-2 / ASTM E90

Tactile 6

Where measurement infrastructure runs out. Four of these six attributes have no standard method for interior surfaces, which is a substantive obstacle to any evidence-based claim about touch.

  • Surface roughness RaArithmetic mean deviation of the surface profile.micrometresISO 21920
  • Texture wavelengthDominant spatial period of the texture, which is what the fingertip actually resolves.mmProfilometry
  • Compliance under loadHow far the surface yields under finger or body pressure.mm/NNo consensus method
  • Skin frictionResistance to a finger drawn across the surface. Measured in tribology research, not in product testing.coefficientNo standard method for skin contact
  • Compression resilienceRecovery after sustained compression.% recoveryISO 3415
  • Perceived softnessRated softness from a human panel. The only tactile attribute that is directly perceptual, and the one with no product-level infrastructure whatsoever.psychophysical ratingResearch technique

Thermal contact 4

Why stone reads as cold and wool reads as warm at the same room temperature. Almost entirely absent from specification documents.

  • Thermal conductivityRate of heat conduction through the material.W/m.KISO 8301 / ASTM C518
  • Volumetric heat capacityHeat stored per unit volume per degree.J/m3.KDerived from density and specific heat
  • Thermal effusivityHow quickly a surface draws heat from skin on contact. This, rather than temperature, is what perceived warmth tracks, and it is why two surfaces at identical temperature feel different.J/m2.K.s^0.5Derived: root of conductivity by density by specific heat
  • Surface temperature offsetSteady-state difference between surface and air temperature in the installed condition.KIn-situ measurement

Olfactory 3

The sensory channel with the most direct anatomical route to limbic structures and the least product-level measurement. Three attributes, two standard methods, and no comparable product data in circulation.

  • Odour intensityPerceived strength of emitted odour from a material sample, rated by a trained panel.comparative scaleISO 16000-28
  • Odour hedonic toneWhether the odour is rated pleasant or unpleasant, independent of its intensity.scaleVDI 3882 part 2
  • Odour persistenceHow long emitted odour remains detectable after installation. The question every hotel operator actually asks, and the one with no test behind it.no standard unitNo standard method