Thermal performance of roofs suitable for developing countries in tropical climate

Abstract

Roof structures have been traditionally built from reed or straw in tropical climate locations. Now, traditional materials are often replaced by pure metal sheets. The roof construction is improved in terms of durability and cost effectiveness, but he roof built from pure metal sheets can cause excessive overheating of interior spaces. The aim of this paper is to compare dynamic thermal performance of different roof assemblies under real boundary conditions. For this purpose, a thermally insulated test box was built on the roof of the university. Six roof samples (0,9 m × 1,1 m) can be mounted on the roof. The roof covering made of pure steel sheet with Zn coating was the reference case. This assembly was then modified step-by-step either by change of colour, or by additional material layers of reed and earth boards, or by 2cm thick ventilated air cavity on the rear side of the sheet. In total, 18 different roof assemblies were tested in three consecutive test runs (approximately three-week periods between 07 – 09-2020). Ventilated air gap and white paint are the best adjustments to reduce heat flux. Dark colours of the metal sheet have the opposite effect. Influence of reed and earth boards was in many cases similar. One roof assembly was selected for use in real project.

Simulation Modelling of Roof Design of Indonesian Airport Terminal For Optimal Utilization of Cooling Energy

“…Therefore, dfferences in roof design and material can affect the thermal performance of buildings and eventually affect the requirement of cooling energy. The effect of roof shape and material on building thermal performance and cooling energy has been studied by (Al-Saadi, 2006), (Čanda & Kopecký, 2021), (Akbari & Konopacki, 1998), (Dixit et al, 2018) [6][7][8][9].. Previous research on the design of building envelopes for thermal comfort and reducing cooling energy in residential buildings by comparing various types of concrete roofs in hot-dry and hot-humid climate in Riyadh and Dhahran, Saudi Arabia explained that the roof should be painted with smooth and light color to reflect the solar radiation (Al-Saadi, 2006).…”

“…Previous research on the design of building envelopes for thermal comfort and reducing cooling energy in residential buildings by comparing various types of concrete roofs in hot-dry and hot-humid climate in Riyadh and Dhahran, Saudi Arabia explained that the roof should be painted with smooth and light color to reflect the solar radiation (Al-Saadi, 2006). Another research on thermal performance of roofs that is suitable in tropical climate was conducted by comparing experimental models metal roofs with different colors and natural insulation, such as reed insulation board and unburn earth board explained that the roof with ventilated air gap and white paint are the best combination to reduce heat [7]. Similarly, the research on impact of reflectivity and emissivity of roofs on building cooling and heating energy used, explains that the white reflective roofs reduce cooling energy consumption by 18-26% and by 28-35% in peak demand [8].…”