Thermal lag and decrement factor of a coconut-ferrocement roofing system

• A real-scale prototype house was built.
• Coconut fibre filled ferrocement precast channel roof components present a thermal offset of 210 min (3½ h).
• A lower thermal damping of 43% compared to ferrocement-only precast channel roof.
• Coconut fibre limits the flow of heat at peak times where temperatures reach their highest values.
• Ferrocement fibre filled precast channel roof components can bring thermal comfort.

In this paper, coconut fibre filled precast ferrocement roofing channel components were developed, their thermal behaviour was characterized and its performance was compared to precast ferrocement-only roofing channel components in a real-scale prototype house built at CIIDIR facilities in Oaxaca, Mexico. The experimental analysis performed in this study was based on dynamic climatology. A solar orientation chart of the place was constructed to identify the solar radiation intensity acting on the house. Measurements of roof surface temperatures were conducted to determine temperature damping and temperature wave lag. Monthly average temperature and direct solar radiation data of the site was considered. Coconut fibre filled precast ferrocement roofing performance was compared to a ferrocement-only roofing and to a traditional concrete slab roofing. Results indicate that, coconut fibre filled precast ferrocement roofing channel components experience higher solar radiation intensity but its thermal damping is 40% and its thermal lag of about three and a half hours. Precast ferrocement-only roofing channel showed no thermal lag or damping and traditional concrete slab roofing exhibit a thermal damping of only 13% and its thermal lag of zero. Thus it is concluded that coconut fibre filled precast ferrocement roofing channel components are an ecological alternative for energy saving and thermal comfort.