Contributions to the design of rainwater harvesting systems in buildings with green roofs in a Mediterranean climate

Abstract

Green roofs (GRs) are becoming a trend in urban areas, favouring thermal performance of buildings, promoting removal of atmospheric pollutants, and acting as possible water collection spots. Rainwater harvesting systems in buildings can also contribute to the management of stormwater runoff reducing flood peaks. These technologies should be enhanced in Mediterranean countries where water scarcity is increasing and the occurrence of extreme events is becoming very significant, as a result of climate change. An extensive pilot GR with three aromatic plant species, Satureja montana, Thymus caespititius and Thymus pseudolanuginosus, designed to study several parameters affecting rainwater runoff, has been in operation for 12 months. Physico-chemical analyses of roof water runoff (turbidity, pH, conductivity, NH4(+), NO3(-), PO4(3-), chemical oxygen demand) have shown that water was of sufficient quality for non-potable uses in buildings, such as toilet flushing. An innovative approach allowed for the development of an expression to predict a 'monthly runoff coefficient' of the GR system. This parameter is essential when planning and designing GRs combined with rainwater harvesting systems in a Mediterranean climate. This study is a contribution to improving the basis for the design of rainwater harvesting systems in buildings with extensive GRs under a Mediterranean climate.

Contributions of Water-Related Building Installations to Urban Strategies for Mitigation and Adaptation to Face Climate Change

“…From the perspective of integrating green roofs with rainwater harvesting systems, previous research has been conducted by the authors and other researchers on a conventional extensive green roof system in Oporto city (Portugal) [35]. This study revealed low runoff coefficient values, but allowed the development of an expression to predict the monthly runoff coefficients for this type of conventional green roof.…”

“…The pilot green roof was established with three different common aromatic plant species: Satureja montana, Thymus caespititius, and Thymus pseudolanuginosus. Although the pilot system was relatively small (0.70 × 0.70 m 2 ) and could lead to scale distortions in the results, it was thought that these errors would not be significant and that the results met the objective of obtaining a practical mathematical expression that would allow, with acceptable approximation, the determination of average values of the monthly runoff coefficient for a typical extensive green roof [35]. Measurements of the pilot green roof allowed the development of the following expression for monthly runoff coefficient prediction [35]:…”

“…(1) Figure 2. Green roof experimental set up [35]. Although the pilot system was relatively small (0.70 × 0.70 m 2 ) and could lead to scale distortions in the results, it was thought that these errors would not be significant and that the results met the objective of obtaining a practical mathematical expression that would allow, with acceptable approximation, the determination of average values of the monthly runoff coefficient for a typical extensive green roof [35].…”

“…Measurements of the pilot green roof allowed the development of the following expression for monthly runoff coefficient prediction [35]: The expression obtained, which significantly depends on the temperature in previous periods and precipitation, has similarities with the well-known Turc formula [36] that has been widely used in hydrological studies to determine flow deficit, which can be considered an indicator of its consistency [35]. It should be noted that, where the application of the formula leads to a C M value greater than 0.50, it is recommended that this value is adopted as a maximum, taking into account indications of the European Standard EN 16941-1 [37].…”

Tipos e eficiência de unidades de tratamento para água pluvial: revisão de literatura

“…A construção de telhados verdes, além de auxiliar nas condições térmicas das edificações, pode ser integrada com um sistema de aproveitamento de água pluvial, agindo como um local de coleta de água e removendo poluentes atmosféricos. Com este objetivo, Monteiro et al (2016) Teixeira et al (2017) Os autores apontam que para completo atendimento às normas da ABNT, seria necessário acrescentar um sistema de desinfecção e sugerem que essa necessidade pode inibir os usuários de adquirir um sistema de aproveitamento de água pluvial.…”