Assessing the real-time thermal performance of reinforced cement concrete roof during summer- a study in the warm humid climate of Kerala

• Published in: Journal of Building Engineering Vol. 41; p. 102735
• Main Authors: Joshima, V.M., Naseer, M.A., Lakshmi Prabha, E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2021
• Subjects: Field studies; Reinforced cement concrete roof; Roof coverings; Thermal performance; Warm humid climate; Warm humid climate; Reinforced cement concrete roof; Roof coverings; Thermal performance; Field studies
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2021.102735

Understanding the real-time thermal behaviour of the building envelope is essential to provide comfortable indoor conditions and to develop energy efficient building components. Monitored performance of sloping Reinforced Cement Concrete (RCC) roofs and roof coverings, which is a widely found roofing typology in warm humid climate, are rarely found in published literature. This paper is based on a comparative study of the real-time thermal performance of different types of RCC sloping roofs – exposed, covered using Mangalore pattern tiles, ceramic tiles, concrete tiles, and shingles sheet. Field studies are conducted in naturally ventilated residential buildings with these roof variants, from warm humid climate during summer. The methodology includes (i) Theoretical study to identify significant thermal performance parameters, (ii) Field studies and testing, and (iii) Comparative analysis of case studies. Theoretical study resulted in the identification of simple empirical indices that can express the dynamic thermal behaviour of roof components; they are decrement factor, time lag, thermal performance index, and adaptive thermal comfort index. Field studies show that elevated ceiling temperature and indoor air temperature persists in all the roof types, deeming these roof-covering techniques as inefficient to provide acceptable thermal comfort conditions during summer in a warm humid climate. Among the roof variants, Mangalore pattern tiles exhibited better thermal performance due to their low conductivity, diffusivity, and slightly corrugated profile. The research also provides useful field data as an add-on to the existing knowledge, to aid energy-efficient building design and performance study of roofing materials. •Identified simple parameters to broadly assess the real-time thermal performance.•Field studies on the thermal performance of five reinforced cement concrete roofs.•Coverings on bare slab improve the decrement factor and thermal performance index.•High relative humidity, high air and ceiling temperature renders thermal discomfort.•Thermal properties and profile of roof covering modulate its thermal behaviour.