Technical Terms
αw: Sound Absorption Class
Sound Absorption / Sound Absorption Coefficient (α):
This term describes a material’s capability to absorb sound waves rather than reflecting them, a property known as “sound absorption.” This process converts most of the acoustic energy into heat energy. It is important to note that sound absorption is distinct from sound insulation.
The sound absorption coefficient measures the ratio of absorbed to reflected sound energy. A value of 0 indicates complete sound reflection, while a value of 1 signifies total sound absorption. For instance, an αw of 0.60 implies 60% sound absorption and 40% sound reflection.
Measurement:
The sound absorption coefficient is determined according to the EN ISO 11654 standard, which also defines the sound absorption value (αw) and categorizes materials into sound absorption classes.
Sound Levels and Frequencies
Sound Level (dB):
Expressed in decibels (dB), this measures the intensity of sound.
Sound Frequency (Hz):
Measured in hertz (Hz), this represents the rate of air pressure changes that produce sound vibrations. Humans can hear frequencies ranging from 20 Hz to 20,000 Hz, with speech typically falling between 500 Hz and 2,000 Hz.
NRC (Noise Reduction Coefficient):
The NRC is a simple measure of a surface’s ability to absorb sound energy.
Scale: An NRC of 0 represents total reflection, while a value of 1 denotes complete absorption.
Calculation: It is the average of the sound absorption coefficients at frequencies of 250 Hz, 500 Hz, 1000 Hz, and 2000 Hz—key ranges for human speech, making the NRC particularly useful for evaluating speech-related acoustics.
Airborne Sound (Rw)
Airborne sound refers to noise transmitted through the air, which may penetrate walls, ceilings, or floors into adjacent spaces.
Improving Sound Insulation: Enhanced sound insulation is achieved by adding insulation materials to structural elements such as walls, floors, or ceilings.
Rw Measurement: The improvement is calculated as:Rw (after) - Rw (before)This metric helps assess the effectiveness of interventions in reducing noise transfer.
Impact Sound
Impact sound is generated by physical contact, such as footsteps or objects striking structural elements like floors or walls.
Measurement Process:
Vibrations are measured on a bare floor due to standardized impacts, recording sound transmitted to the room below (frequency range: 100–5000 Hz). These values are summarized into a single metric: L’n,w,R.
Measurements are repeated after insulation is applied. The greater the reduction in sound level, the more effective the insulation.
Key Terms:
Ln: Impact sound level measured without accounting for indirect transmission.
L’n: Impact sound level including indirect transmission.
Ln,w: Frequency-independent impact sound level.
L’n,w: Frequency-independent impact sound level, including indirect transmission.
Ln,w,R: Improvement in impact sound level after insulation.
Inter-room Sound Insulation
This is assessed following ISO 10848-2 and EN ISO 717-1 standards to evaluate sound transmission between rooms.
Weighted Standardized Façade Level Difference (D₂m,nT,w)
This metric calculates the difference between the sound pressure level measured 2 meters in front of a façade (e.g., from traffic noise or specific sources) and the level within the receiving room.
Fire Resistance Class
Fire resistance is classified according to the TS EN 13501-1 standard, based on the material’s reaction to fire:
A1: Non-combustible.
A2, B1: Difficult to ignite.
C, D: Normally flammable.
E, F: Easily flammable.
A1 is the highest rating, indicating non-combustibility, while lower classes represent progressively easier ignitability.
s1, s2, s3: These terms classify smoke emission levels:
s1: Minimal or negligible smoke emission.
s2: Moderate smoke emission.
s3: High smoke emission.
d0, d1, d2: These terms describe the behavior of burning droplets:
d0: No burning droplets or particles for at least 60 seconds.
d1: Limited burning droplets or particles.
d2: Continuous or high levels of burning droplets.
Thermal Properties
Thermal Conductivity (λ: mW/mK)
This value measures a material’s efficiency in conducting heat and is outlined in the TS 825 Thermal Insulation Rules for Buildings standard. Lower thermal conductivity values indicate better insulation properties, as the material conducts less heat. For optimal thermal insulation, the conductivity value should be as low as possible.
Thermal Resistance (R)
Defined by the formula:R = d / λWhere:
R: Thermal resistance.
d: Thickness of the material.
λ: Thermal conductivity.
Thermal resistance increases as thermal conductivity decreases or material thickness increases, leading to better insulation performance.
Additional Performance Metrics
Wet Scrub Resistance:
This measures a surface’s durability against repeated wet scrubbing. Testing and classification follow the TS EN ISO 11998 standard.
Corrosion Resistance:
Refers to a material’s ability to withstand chemical and environmental degradation without losing its structural integrity or bonding properties.
Sag Resistance:
Indicates a material’s ability to resist deformation or sagging under applied loads while suspended.
L Value (Whiteness Index):
Indicates the level of whiteness in a material:
A value close to 100 signifies high whiteness.
A value approaching 0 indicates increasing blackness.
Measurements are performed according to the ISO 7724 standard.
Impact Resistance:
Measures the amount of energy a material can absorb before breaking under dynamic forces. Tested according to EN 13964, Appendix D.
Surface Durability:
Evaluated for resistance to wet scrubbing, rated on a scale from 1 (highest durability) to 5 (lowest durability), based on EN ISO 11998:2007.
Moisture Resistance:
Assesses a material’s ability to withstand exposure to high humidity or persistent condensation without degrading.
Air Leakage:
Determines the rate of air seepage in pressurized areas requiring a differential pressure.
Light Reflection (Albedo):
Represents the percentage of light reflected by a surface:
100% Albedo: The surface reflects all incoming light.
0% Albedo: The surface absorbs all light and reflects none.