Impact of translucent water-based acrylic paint on the thermal performance of a low cost house

摘要

Insulation materials are selected based on their R-value, which is a measure of the thermal resistance of a material. Therefore, the higher the R-value of a material, the better its thermal insulation performance. There are two major groups of insulation materials: bulk and reflective insulation (or combine bulk and reflective). Bulk insulation is design to resist heat transfer due to conduction and convection. Reflective insulation resists radiant heat flow due to its high reflectivity and low emissivity. Insulation materials are not restricted to these materials only. Other low thermal conductive materials can be used as long as the primary aim of thermal insulation, which is increasing thermal resistance, is achieved. Hence, the aim of the project is to investigate the insulation ability of Translucent Water-based Acrylic Paint (TWAP) on the thermal performance of Low Cost Housing (LCH). To achieve the aim of the study, the inner surfaces of the external walls of LCH was coated with TWAP. Before the inner surfaces of the external walls were coated, the following techniques were used to characterised the paint; Scanning Electron Microscopy/ Energy Dispersive X-ray spectroscopy (SEM/EDX), Fourier Transform Infra-Red (FTIR) and IR thermography. SEM/EDX was adapted to view the surface morphology and to detect the elemental composition responsible for the thermal resistance of the TWAP. FTIR spectroscopy was used to determine the functional group and organic molecular composition of the paint. The heat resistance of TWAP was analyzed using IR thermography technique. A low cost house located in the Golf Course settlement in Alice, Eastern Cape, South Africa under the Nkonkobe Municipality Eastern Cape was used as a case study in this research. The house is facing geographical N16°E, It comprises a bedroom, toilet and an open plan living room and kitchen. The house has a floor dimension of 7.20 m x 5.70 m, giving an approximate area of 41 m2. The roof is made of galvanized corrugated iron sheets with no ceiling or any form of roof insulation. The walls of the buildings are made of the M6 (0.39 m 0.19 m x 0.14 m) hollow concrete blocks, with no plaster or insulation. The following meteorological parameters were measured: temperature, relative humidity, solar irradiance, wind speed and wind direction. Eleven type-K thermocouples were used to measure the indoor temperature, inner and outer surfaces temperature of the building walls. Two sets of HMP50 humidity sensors were used to measure the indoor and outdoor relative humidity as well as the ambient temperature. The indoor temperature and relative humidity were measured at a height of 1.80 m so as to have good indoor parameter variation patterns that are not influenced by the roof temperature. The outdoor relative humidity sensor together with a 03001 wind sentry anemometer/vane and Li-Cor pyranometer were installed at a height of 0.44 m above the roof of the building. Wind speed and direction were measured by the 03001 wind sentry anemometer/vane, while solar radiation was measured by the Li-Cor pyranometer. The entire set of sensors was connected to a CR1000 data logger from which data are stored and retrieved following a setup program.