Hydrological Performance of Green Roof Systems: A Numerical Investigation

Green roof systems could help reduce peak discharge and retain rainwater in urban areas. The objective of this study was to investigate the hydrological behavior of a green roof system by using the SEEP/W model. The rainfall-runoff relationship within the green roof system was simulated and the results were compared with actual data from a test bed for green roof systems to verify the applicability of SEEP/W. Then, the verified SEEP/W model was used to simulate the green roof system by varying four factors (soil type, rainfall intensity, substrate depth, and green roof slope) to explore the hydrological performance through the peak discharge to rainfall intensity (PD/RI) ratio and the rain water retention rate. The results show that the model presents slightly faster and greater peak time and peak discharge values, respectively, as compared to the observational data. This is attributed to the vegetation conditions in the real green roof system. However, it is also shown that the SEEP/W model can be used to design green roof systems and evaluate their hydrological behavior because of its modeling efficiency. Thus, the SEEP/W model can be used to reliably design and manage green roof systems by further considering the vegetation conditions and water flow dynamics. Furthermore, it would be desirable to consider additional factors, such as vegetation and an insulating pebble layer, in the design and management of green roofs in future work.

Evapotranspiration Measurements and Assessment of Driving Factors: A Comparison of Different Green Roof Systems during Summer in Germany

Green roofs have proven to be a space-saving solution to mitigate peak temperatures and control floods in urban areas through evaporative cooling and storm water retention. To encourage a sustainable city design with large-scale green infrastructure networks, a better differentiation between the diverse existing green roof systems is needed. The aim of this study is to demonstrate differences among green roof systems based on comprehensive microclimatic measurements on four small experimental roofs and to assess differences in evapotranspiration with a partial least square regression. The results show that short-wave solar radiation, relative humidity and water availability are the most important drivers of evapotranspiration. The roof system with permanent water storage maintained significantly higher substrate moisture compared to the other roofs and produced peak evapotranspiration rates of 4.88 mm d−1. The highest total evapo-transpiration of 526 mm from April to September was recorded for the roof system with the thickest substrate layer and grass vegetation. In summer, the shallowest roof showed the highest substrate temperature and air temperature at vegetation level. These findings highlight the importance of specifying the characteristics of the various green roofs in order to turn them into useful planning tools for the design of climate-change-resilient cities.

Carpintería de armar con lacería en iglesias de la región de Murcia. Conceptos básicos y características de estas techumbres de madera

A principios del siglo XVI, el Reino de Murcia experimenta un notable aumento de población que conlleva la construcción de numerosas iglesias. En general, estos nuevos templos se caracterizarán por el sistema de techumbre de madera a base de carpintería de armar con lacería. En muchos textos, a estas construcciones históricas se les ha denominado como “iglesias mudéjares” o “iglesias moriscas”, y su tipología ha sido relacionada con los modelos granadinos, sevillanos, levantinos (por el uso de arcos transversales o diafragma) o castellanos, dependiendo del autor que analizara estas construcciones. El presente texto pretende exponer las características formales y constructivas de estas iglesias y sus techumbres de madera, los sistemas de aprendizaje y trabajo de los autores de las cubiertas (bajo el control de los gremios de carpinteros y regulado por las correspondientes ordenanzas), y justificar por qué no se deben atribuir estas edificaciones a carpinteros mudéjares o moriscos sino a carpinteros procedentes de áreas de Castilla y por qué deberíamos denominar estos trabajos como carpintería de lazo. Con ello, se pretende contribuir al conocimiento y difusión de estas magníficas soluciones estructurales y decorativas de carpintería de armar, con lacería, que aún se conservan el nuestra Región, contribuyendo así a su conservación. At the beginning of the 16th century, the Kingdom of Murcia experienced a notable increase in population that led to the construction of numerous churches. In general, these new temples will be characterized by the carpentry-based wooden roof system of arming with lacework. In many texts, these historical constructions have been called "mudejar churches" or "moorish churches", and their typology has been related to the Granada, Sevilla, Levantine (due to the use of transverse arches or diaphragm) or Castilian models, depending on the author who analyzed these constructions. This text aims to expose the formal and constructive characteristics of these churches and their wooden roofs, the learning and work systems of the authors of the roofs (under the control of the carpenters' unions and regulated by the corresponding ordinances), and justify why these buildings should not be attributed to “mudejar” or moorish carpenters but to carpenters from areas of Castile and why we should call these works as laced carpentry. With this, it is intended to contribute to the knowledge and dissemination of these magnificent structural and decorative carpentry solutions to be assembled, with lacework, which are still preserved in our Region, thus contributing to their conservation.

A preliminary Study on The Use of PET Bottle Waste as The Green Roof Drainage Layer for Thermal Insulator

The phenomenon of urban heat island (UHI) and global warming are significant issues now in relation to sustainable urban development. The application of green roofs is an intention to weaken the impact of UHI by reducing heat gain on the building surface that is emitted to the environment. In addition, green roofs also reduce heat transmission from solar radiation received by the roof to the indoor. Utilization of plastic bottle waste from PET (Polyethylene Terephthalate) will cut down the weight of the green roof system, which also develops the heat resistance value of the roof. This research is an initial study that suggests a green roof application that is more environmentally friendly with the principle of reusing PET waste as a sustainable building material to increase thermal resistant of the system. The analysis concentrates on describing the thermal behavior of the green roof system with the inclusion of PET bottles as a drainage layer. The investigation was carried out by preparing a cubical model of 60cm x 60 cm x 60 cm with a green roof system. Thermal performances were assessed by measuring the temperature of each layer of the green roof using thermocouple wire. The environmental variables measured were solar intensity, ambient air temperature, and air humidity, where the sensors placed close to the models. This analysis demonstrates the influences of green roofs in reducing solar radiation heat. Even though the decreasing of room temperature between the models was not significantly different, this initial results show that, by introducing PET, still display a further performance in reducing heat gain from solar radiation. However, it is necessary to adjust the evaluation models. Heat accumulation in room raised the indoor temperature to be higher than the roof temperature, so that the behavior of the green roof with the purpose of PET is not obviously distinguishable. A trial model with ventilation opening will release heat from enclosed space and it could evaluate clearly the rate of heat flow from the roof.