A Comparison of Banana Fiber Thermal Insulation with Conventional Building Thermal Insulation

The use of conventional non-biodegradable building thermal insulation has resulted in environmental issues which prompted research to focus on the use of natural fibres in many regions. The thermal insulating properties of banana fibre was investigated and compared with conventional insulating materials to ascertain the use as building thermal insulation. Thermal conductivity measurements were conducted in accordance with ASTM C-518-04 on 38 mm thick slab-like banana fibre specimens. Experiments were conducted for the density range 20 kg/m3 to 120 kg/m3 in increments of 10 kg/m3 and for mean test temperature range 20°C to 40°C in increments of 5°C. Results showed that banana fiber exhibited the characteristic behaviour associated with fibrous thermal insulation of decreasing thermal conductivity with increasing density to a minimum value and then increasing in thermal conductivity with further increase in density. Consistent with loose fill materials, there was a linear increase in thermal conductivity with increase in mean test temperature. An empirical equation developed to calculate the apparent thermal conductivity variation with density and temperature correlated within ±4.42% of the experimental results. At 25°C the experimental results showed a minimum thermal conductivity of 0.04110 W/m.K at 80 kg/m3 and the empirical equation 0.04150 W/m.K at a density of 73.4 kg/m3. The empirical and experimental minimum thermal conductivity was within 0.96%. The comparative thermal conductivity of banana fiber with conventional non-biodegradable insulation show the minimum thermal conductivity was higher than all the conventional insulation. The difference ranged from 8.5% (a λ difference of 0.0035 W/m.K) for glass fiber to 24.0% (a λ difference of 0.0099 W/m.K) for urethane foam. Although the banana fiber showed the highest thermal conductivity among the materials compared, its value was within the 0.02 W/m.K to 0.06 W/m.K range for use as building thermal insulation.