The reuse of discarded plastic water bottles as an insulating material for external walls in buildings

Abstract

The thermal conductivity of exterior wall insulation affects the overall energy consumption of a given building. Fiberglass insulation is often used for this application. This research investigated the feasibility of replacing typical fiberglass insulation with used empty Polyethylene Terephthalate (PET) bottles. In addition to potential cost savings, replacing fiberglass insulation with PET bottles on a large scale could help alleviate the environmental impact of sending these bottles to landfills. A small 8-inch by 8-inch wall section constructed with sheet metal and drywall was used for testing, maintaining a 3-inch airspace for proposed insulation. Thermal resistance was measured with the airspace packed with empty water bottles and comparisons were made to the same wall sections void of any water bottles. Testing was conducted both with and without a 1/2-inch foam board present for comparison. Kapton heaters and temperature sensors were used for the simulation. Preliminary testing showed promise for the proposed application. The effectiveness of the plastic water bottles at providing insulation properties increased with decreasing voltage in both test setups (both with and without the foam board) and was most effective when the foam board was present. Further research is needed to determine how the use of PET bottles for exterior wall insulation can be implemented on a larger scale and how R-values can be improved.