Driving factors for facade rainwater harvesting in high-rise buildings

Abstract

Water is the most vital natural resource for all life on earth and it affects people health and wellbeing, economy and the environment. However, millions of people throughout the world still donot have enough access to fulfil this basic necessity. Thus, scarcity and the accelerating demand of water are major problems in nowadays. With respect to the sustainable management of freshwater, the of alternate or additional water resources are uses highly considered in the worldwide. In this context, rainwater harvesting has become a great necessity specially in building designs due to high water consumption, high demand on main water supply and increase of water utility bills. However, rainwater harvesting is not a new technique to collect and store rainwater for the later usage in any buildings and' can be retro-fitted to existing buildings or integrated into new building designs. Rainwater harvesting can be implemented by using various existing structures such as rooftops, parking lots, playgrounds, parks, ponds and building’s facade. Even though, other structural elements highly used in this mechanism, the less consideration and less priority have been given to the rainwater that collected through 'building’s fagade1. However, it is a still remaining researchable area , as it is a new technique used in few high-rise buildings in Sri Lanka according to the key literature findings. Therefore, this emphasizes the importance of studying the applicability of facade rainwater harvesting system in buildings designs. Thus, this paper discusses possible driving factors and design criteria which impact on facade rainwater harvesting in high-rise buildings in Sri Lanka. First, available literature was critically reviewed and, structured questionnaire survey was conducted among the industiy practitioners vyho are involved in rainwater harvesting design and construction in buildings. Relative Importance Index (RH) was used to analyse the questionnaire data and further, t-test was used to identify the significant driving factors affecting on facade RWH system. It was identified climate (rainfall pattern) and intensity of the rainfall as the most significant factors. Furthermore, the paper discusses suitable design criteria of facade rainwater harvesting in terms of implementing stage, building shape, height and type of facade materials.