Performance recommendations by type of insulation
What do you need to know before reusing recovered insulation?
Below is an overview of some general conclusions on the performance of different types of insulation material collected within this project.
For more targeted guidelines on a specific case, we recommend completing the digital tool under the 'Performance assessment' path.
By type of insulation
Key aspects of the performance of naturally aged glass wool and rock wool insulation:
Moisture is the biggest enemy — mineral wool insulation can degrade after prolonged contact with moisture
Old mineral wool loses its water repellency and can absorb more water, more quickly
Noticeably higher water absorption after prolonged contact with ambient air
Old mineral wool retains its thermal performance as long as it is and stays dry
Thermal conductivity depends strongly on density
More scatter in thermal conductivity at higher densities (>100 kg/m³)
Measured values are 21 - 34% lower than the default value imposed by EPB (0.050 W/m.K)
Key aspects of the performance of naturally aged PUR/PIR insulation:
Take care with PUR/PIR from damp flat roofs: degradation due to prolonged contact with moisture
Damp boards (density > 60 kg/m³) are difficult to dry naturally: low reuse potential
Compressive strength remains good: at least >120 kPa and often >150 kPa
PUR = dimensionally unstable at high temperatures (70°C) and high relative humidity (90%)
Large variation in thermal conductivity: density (moisture), type of facing, thickness and age have a major influence
Measured values are 17 - 35% lower than the default value imposed by EPB (0.035 W/m.K)
Key aspects of the performance of naturally aged EPS insulation:
EPS absorbs water quickly in case of excessive contact with water
EPS is dimensionally stable under extreme conditions, but can sometimes show slight expansion in the thickness direction
The compressive strength and thermal conductivity of EPS depend on density
Measured values are 15 - 31% lower than the default value imposed by EPB (0.050 W/m.K)
Key aspects of the performance of naturally aged XPS insulation:
Aged XPS remains relatively water-resistant, but water absorption is often slightly above the current limit value of 0.7%
XPS remains dimensionally stable under extreme conditions
The compressive strength of XPS is highly variable, but is well retained
The thermal conductivity of XPS depends strongly on: original application (wet or dry), year of production and density
Measured values are 19 - 34% lower than the default value imposed by EPB (0.045 W/m.K)
The benefit of measuring/knowing the thermal conductivity (λ)
When no original technical data sheet is available for reused insulation, the EPB regulations require the default value to be applied. The chart below compares this value for each insulation material with the average measured thermal conductivity from the research.
This shows that knowing or measuring the actual thermal conductivity can lead to more efficient use of material. The more accurately this performance is estimated, the more precisely the insulation thickness and the reuse application can be designed.