Reduction of temperature fluctuation in a South African shack house using phase change material insulation

Abstract

The majority of South African informal settlements are made from corrugated profile galvanized metal sheets. These informal settlements are prone to temperature fluctuations due to high thermal conductivity of the metal sheet and its low thermal resistance to heat transfer between the exterior and the interior of the shack. Families have resorted to using fuels such as paraffin during cold days, which has resulted in fire outbreaks that ravage surrounding shacks. This study experimentally investigated the temperature fluctuations around a shack fitted with plank chipboard and one without. Energy plus 22.2.0 software was then used to simulate the temperature fluctuations effects after integrating a Phase Change Material (PCM) layer on the shack walls. From the experiments, the internal temperature fluctuations on the shack without the insulations reached close to +50 °C during the day, and −5 °C during the night. While the shack with insulation reached +25 °C during the day and 7 °C during the night. The temperature distribution inside the shack was observed to be uneven, with the top section of the shack at higher temperatures than the bottom section. The region and the location of the shack largely contributed to the temperature fluctuations. Simulations revealed that by integrating a PCM layer in the shack walls, temperature fluctuations were greatly reduced. A lower phase change temperature yielded greater results as the atmospheric air allowed the PCM to fully solidify and melt, thus releasing the latent heat energy. A phase change temperature between 17 and 19 °C was selected based on the average atmospheric yearly temperature range. A 30 mm thick PCM reduced the temperature fluctuations to between +14 °C and +16 °C. However, materials with high thermal conductivity are not well supported by the Conduction Finite Difference used to simulate the performance of a phase change material in energy plus, it is proposed to remove such thin and high conductive materials in the model.