Innovative panels with recycled materials: Thermal and acoustic performance and Life Cycle Assessment

Insulation is one of the most effective methods intended for reducing energy consumption in both heating
and cooling of buildings. Selecting the right materials and determining the optimum insulation thickness
in building insulation application is an important issue. Moreover it is important to use green
insulating materials in order to limit the environmental impact in the use of these solutions. A growing
interest is focused on the incorporation of low cost recycled materials in building products and their
potential use as insulating panels for both new buildings and refurbishments.
In this paper two panels were investigated, composed by waste paper and textile fibres, joined by glue,
with a total thickness of 12 mm and 20 mm respectively. The study is focused on the thermal and acoustic
characterisation of the panels, in order to provide accurate data for a reliable building integration.
Thermal performance was evaluated by using the hot-box apparatus, according to UNI EN ISO 8990. A
good thermal behaviour was found for all the investigated panels: k-values vary in the 0.034–0.039
W/m K range. The investigated panels could be a valid solution in place of classic insulation systems, even
though thermal resistance is strongly influenced by the environmental humidity, the rate of the compression,
and the presence of air between the layers. Therefore a thermal infrared camera was also used during
the measurements, aiming to investigate the weak points of the assembled panels and to select the
positions of the sensors.
The acoustic absorption coefficient was determined by means of a Kundt’s tube, in compliance with ISO
10534-2. The Noise Reduction Coefficient (NRC – the arithmetic value of the absorption coefficient at the
frequencies 250, 500, 1000 and 2000 Hz) of the samples varies in 0.23–0.38 range, depending on the layer
thickness.
Finally an initial Life Cycle Assessment of the proposed solutions was considered and compared to the
performance of other replaceable insulating materials. Results showed that the panel composed by recycled
papers and textile fibres causes relative large energy consumptions and a high global warming
potential. The importance of this kind of insulation system is due to the use of recycled materials: both
the waste paper and the TNT fibres should be disposed by means of a large use of energy. This way they
will be re-used and the cost for the production of the panels is very low. A disadvantage of these panels
could be their high density (about 433 kg/m3): the future step for this work will be the improvement of
this new insulating type in order to obtain a competitive solution on the market.