COMPARATIVE ANALYSIS OF THERMAL PERFORMANCE OF SELECTED WALLING MATERIALS FOR TROPICAL BUILDINGS IN LOKOJA, NIGERIA.

Abstract

Thermal performance of a building refers to the process of moderating the energy transfer between a building and its surroundings. The knowledge of thermal performances of timber, laterite - cement and sandcrete block walls that are commonly used as walling material is very important for occupants’ well-being in the tropical zone. The study area lies in the warm humid zone with its attendant’s high temperature all year round. Thus, providing an acceptable walling material that will control the high indoor temperature becomes imperative. This thesis assessed the three walling materials that are prominently used in Lokoja, to determine the thermal performances for effective thermal comfort of the residents. It involved the construction of three habitable model buildings using the three selected walling materials of timber, laterite-cement blocks and sandcrete hollow blocks in the area. Three units of Cryopak iMINI Temperature and Humidity Data Loggers called (New generation intelligent iMINI) with Serial Numbers and Product Codes MX-CI-1450007 MX-CI-145-0008, MX-CI-145-0009 and MX-HE-S-16-L were installed to record indoor air temperature and relative humidity data at an interval of one hour, for twelve months covering dry and wet seasons. The recorded data were downloaded to excel spread sheet for assessment and analysis. The values were computed using Temperature- Humidity Index (THI) equation. The study revealed that, timber wall provides better thermal comfort for the indoor environment for both seasons. The mean value - average indoor air temperature of timber walling for dry and wet seasons is 30.10C and 29.50C respectively and the relative humidity is 48.7% in dry season and 72.5% in wet season. Laterite- cement block wall recorded 31.3 0C in dry and 30.0 0C in wet seasons. In the same vain, the recorded data of indoor relative humidity had shown that, 46.1% in dry season and 71.5% in wet season. The third walling material which is the sandcrete hollow block wall recorded Mean Value Average indoor air temperature of 30.5 0C and 29.7 0C in dry and wet seasons respectively. While, the indoor relative humidity was put at 47.8% and 73.8% for dry and wet seasons respectively. Given the foregoing, timber wall material building had the lowest recorded indoor air temperature for both dry and wet season, followed by sandcrete block wall and lastly laterite – cement wall. The study concludes that proper building orientation, provision of soft landscaping elements, introduction of insulation and inclusion of other shading devices can improve users’ comfort. It will also ameliorate the heat effect on the external surface of buildings that is transferred into the interior by conduction, radiation or convection within the area and in the tropics at large.