The impact of temperature and humidity on the thermal resistance of waste materials for the efficiency of the building envelope
A thermal insulation material’s effectiveness is influenced by its thermal conductivity and ability to maintain its thermal characteristics, particularly in hot and humid environments. In this study, different waste materials used in building envelopes are investigated for their thermal conductivity under temperature and humidity variations. Four materials are being studied experimentally; rubber, paper, plastic, and foam are mixed separately and proportionally with plain mortar. Thermal conductivity in testing samples is determined using heat-flow meters. Testing waste materials in a room environment for 14 days revealed varying degrees of thermal resistance. Compared to plain mortar, the inclusion of rubber, plastic, paper, and foam increase thermal resistance by 1.6, 43.4, 50.5, and 101.4%, respectively. In a climatic testing chamber, samples were exposed to extreme temperatures and humidity levels consistent with Bahrain’s monthly average temperatures. To determine the effect of changes in temperature and humidity on each waste material’s thermal properties, the thermal resistance of the samples was measured after 24, 48, and 72 hours. The change in environmental factors seems to have a mild impact on rubber’s thermal resistance. Most materials are foam and plastic, while paper and paperboard are moderately affected. Such a change is not substantial for the four tested waste materials during the July environment. Foam, which has demonstrated more significant changes throughout the January environment, shows fewer changes than rubber, paper, and plastic. In an extreme environment, all the tested waste materials, except for plastic, are highly influenced by exposure to extremities of temperature and relative humidity.