Estimation of U-value of traditional North African houses

The heat transfer and the U-values of wall layers in traditional North African houses in Libya have been estimated. The locally produced building materials during 1970’s were used in the construction of such buildings. These materials were limited to bricks, tiles, cement plasters, mortar and ground soils without any insulation components. The masonry construction of these houses was based on concrete-backed stone masonry made of limestone bricks joined by mortar forming the outer walls of the building envelope. Based on the periodic seasonal weather conditions, within the Libyan cost region during summer and winter, measured thermal conductivity values were used to implement such seasonal variation of heat flow and the temperature variations through the walls. The estimation of the U-values is based on measurements and calculations. The experimental measured thermal conductivity values were obtained using the Hot Disk method known as Gustafsson’s probe. The numerical calculations were done using an analytical model that considers different wall and floor constructions which are characteristics of such houses. According to the obtained results, the U-values were quite high and therefore, several suggestions have been proposed to improve the thermal loading performance that will lead to a reasonable human comfort and reduce energy consumption.

► Five construction materials of a Libyan house were used to estimate the U-values.
► The materials are limestone bricks joined by mortar, plaster, soft soil and tiles.
► The calculated U-values are for the external walls and the ground floor.
► The work provides basis for insulation manufactures to produce reliable insulation.
► The lab measurements may not be true indicative of property of material in service.