Street trees’ management perspectives: Reuse of Tilia sp.’s pruning waste for insulation purposes

The management and care of urban greenery is essential to ensure the effective delivery of the ecosystem services it is capable of supplying. A sufficient and adequate care for urban greenery and in particular for urban forestry is an on-going challenge due to economic hardship of public administrations, to a lack of qualified personnel, and to a lack of a culture of valorization of public goods. To identify an opportunity to reuse any by-products resulting from pruning operations could signify economic benefits that could be invested in a better maintenance of urban arboreal patrimony, following a circular economy approach. This paper is the first step of a wider research that has the goal to delineate a strategy for the utilization of the pruning waste of the urban trees as thermal insulation materials. Particularly, in this paper is studied one of the most common tree species in urban greening and forestry: Tilia sp. Three tiles with different densities obtained mixing wood wool and PVA glue are realized and tested. The resulting thermal conductivity and specific heat varying respectively from 8.30 ± 0.54 to 8.60 ± 1.40 10-2 W/m*K, and from 2.26 ± 0.51 to 2.80 ± 0.65105 J/m3*K. Using these values, the paper developed a thermal simulation model, regarding the insulation of the roof of a residential building. The model aimed at comparing the thermal performance of the studied tiles, with two commercial materials produced with wood residues from the timber industry, and with the fibers of two vegetable crops, widely used as insulating materials. The linden tiles entailed an energy saving of 55% respect to the model without insulation, the other materials between 51 to 62%. The results show as the Tilia sp.’s pruning waste could be a good source material to create panels for thermal insulation.