Thermal performance of potted plants in mitigating indoor temperature in tropical climate

Abstract

Reducing indoor heat gain from the roof into the building means reducing the cooling energy consumption of air conditioning system hence increase indoor comfort. Apart from its high initial installation cost, green roof is proven to be the best way in dealing with the issue of indoor heat gain in a building thus contributes in reducing urban heat island effect. Green roof also called eco-roof or vegetated roof is described as a roof that is planted with specific vegetation above a waterproofing membrane. A study in Malaysia suggested that potted plants as an alternative to more economic green roof and its potential in dealing with indoor heat gain needs further exploration. Potted plants are plants grown in containers or pots instead of planting them in the ground. This study investigated the potential of potted plants as an affordable alternative tool to green roof application in reducing indoor temperature in tropical climate regions. Four similar test cells equipped with data acquisition system were built. Each top of the cell is treated with four different design variables; potted plants, vegetated, non-vegetated 150mm depth soil layer and a bare top surface. Indoor peak heat value and lowest value were recorded and analyzed. At heat peak hour, potted plants managed to reduce a daily average of 8.7% indoor heat gain whereas vegetation cell only managed to reduce an average of 7.9% indoor heat gain. Potted plants were also found to reduce a daily average of 35.5% of total heat transfer amount compared to 28.5% in vegetated cell. Based on these results potted plants appear to offer an alternative strategy towards reducing indoor temperature. In conclusion, this study suggests that potted plants could provide an affordable way especially to urban population in their strategy to deal with the high energy consumption for cooling.