Life cycle energy assessment and economic feasibility of stormwater harvested from pervious pavements.

Pervious pavements are one of the most used construction techniques among the Sustainable Urban Drainage Systems (SUDS). The objective of this article is to analyse the energy life cycle and the life cycle cost of stormwater harvesting systems using pervious pavements models in order to compare and evaluate the differences and verify what influences the profitability and sustainability. The method proposed started with the definition of pervious pavement models based on literature review. The main characteristic of the models analysed was the use of porous asphalt with different underlying layers, i.e. thickness and material. The hydrological-hydraulic design of the pavements was also assessed. The potential for potable water savings due to harvesting stormwater from a parking lot was estimated for a public building in Florianópolis, southern Brazil. The models were compared to identify what most influences the potable water savings, the profitability and the sustainability of the systems. The maximum potable water savings found were 42%. It was also observed that the overall consumption of the building has been decreasing over the years, and the yearly rainfall has increased, which leads to a higher potential. In the current water consumption pattern, none of the systems evaluated was profitable or presented sustainability, evaluated herein as negative energy balance. However, it was verified that if analysed comparatively with non-pervious pavement, it was profitable to use stormwater harvested from the pervious pavement. Thus, it can be concluded that stormwater harvesting systems in combination with pervious pavements are promising, serving as SUDS and saving money for users. It is also noticeable that the use of porous asphalt is not recommended when aiming for systems with low embedded energy.