Performance assessment of recovered insulation.
Within this part of the research, various technical properties and performance characteristics were investigated for insulation materials that had been in use in buildings for several years. The aim was to determine which insulation materials retain their original performance well, where degradation may occur, and what performance can realistically be assumed when the material is given a second life.
67 case studies, 5 key parameters, measured in a standardised way.
First, the insulation materials from the 67 case studies were carefully inventoried and relevant background information was collected for each case. This included the original application, the method of fixing, and the age and year of production of the material.
Next, the insulation boards were cut into test specimens of the right dimensions for the various tests. In total, more than 1,200 test specimens were prepared within the research. For each test specimen, the thickness and density, among other things, were determined, after which the specimens were conditioned under controlled conditions and prepared for further testing.
For each insulation material, the thermal conductivity and water absorption were measured. For pressure-resistant and/or synthetic insulation materials, such as EPS, XPS, PUR/PIR or pressure-resistant mineral wool, the compressive strength at 10% deformation and the dimensional stability were also examined.
Finally, where possible, the measurement results were compared with the original product specifications from historical technical data sheets and technical approvals (ATGs). The results were analysed per material type and formed the basis for the guidelines drawn up within the research, which were then translated into the digital tool.
What exactly was measured?
Within this project, the focus was on 5 key parameters for reusing insulation materials. Of course, not all tests are relevant to every kind or type of insulation material.
Density indicates how much mass of insulation material is present per unit of volume and is expressed in kg/m³. To determine it, the mass and volume of the test specimens were measured and converted to density in accordance with NBN EN ISO 29470:2020. Throughout the research, this proved to be an important parameter for estimating the performance of reused insulation materials.
Thermal conductivity, or λ value, is the most important parameter for insulation materials. It indicates how well a material conducts heat: the lower the value, the better the material insulates. The test specimens were measured under controlled conditions using a heat flow meter in accordance with NBN EN 12667:2001.
Compressive strength indicates how much load an insulation material can take before it deforms. It is particularly relevant for floor and roof applications where the panel is subjected to specific loads. In the research, the material was compressed and the compressive stress at 10% deformation (in kPa) was determined in accordance with NBN EN ISO 29469:2022. This parameter was only tested on pressure-resistant insulation materials such as PUR/PIR, EPS, XPS and high-density mineral wool.
Dimensional stability indicates the extent to which an insulation material retains its original dimensions under changing environmental conditions. In accordance with NBN EN 1604:2013, the test specimens were exposed both to warm, humid conditions (70 °C and 90% relative humidity) and to extremely cold conditions (-20 °C), after which the dimensional changes were determined as a percentage. Within the research, this property was only tested on synthetic insulation such as PUR/PIR, EPS and XPS.
Depending on the type of insulation, a short-term or long-term water absorption test was carried out.
Mineral wool insulation and cellulose: for short-term water absorption, the test specimens were partially immersed in water for 24 hours and the amount of water absorbed was determined from the increase in mass, in accordance with NBN EN ISO 29767:2019, method A.
PUR/PIR, EPS and XPS: for long-term water absorption, the water uptake after 28 days of full immersion was determined in accordance with NBN EN ISO 16535:2019.