Jiasen PAN*, Ruiqi LI, Riying XU2, Qifa LI, Xuewei ZHU

1. College of Urban Construction, Jiangxi Normal University, Nanchang 330022, China; 2. College of Foreign Language, Jiangxi Normal University, Nanchang 330022, China

Abstract With the development of the times, the contradiction between human living and the natural environment becomes increasingly prominent. People pay more and more attention to the protection of the natural environment while improving the living standard. While, the emergence of the ecological roof can greatly improve the urban ecological environment and make full use of the architectural space. On the premise of analyzing the current status and significance of research on the ecological roof, this paper puts forward some ideas about the research on the design of the ecological roof with intelligent management system which can be used as a reference for the design of the ecological roof in the future, based on giving full consideration to the factors of ecological energy-saving, environmental protection, economic development, etc., and summarizing the shortcomings of the traditional ecological roof.

Key words Intelligentization, Management system, Ecological roof, Design

1 Introduction

With the expanded boundaries of current economic globalization, interweaving and conflicts between human activities and the natural environment keep coming. With the expansion of human living area, the development of environment has also become a hot issue. It makes us have to think about how to alleviate the contradiction between human living environment and natural environment, protect the natural environment, and improve people’s living standards. The ecological roof which is covered with soil for growing plants has a good ecological effect[1]. It has a positive ecdogical effect, not only on the protection of buildings’ surface, but also on the control of indoor temperature and reduction of global warming. It is worth researching and discussing to create a new ecological roof based on appropriate innovation and transformation with intelligent management system.

2 Significance of the research

2.1 Improving the urban ecological environmentThe green coverage rate of urban buildings in China is generally low at present. It will meet the needs of urban greening by greatly increasing the area and rate on condition that plants can be effectively used in the interior of the roofs of urban buildings. The plants in the ecological roof can effectively adsorb the smoke and dust in the air of the building, and convert the carbon dioxide in the atmosphere into water and oxygen with photosynthesis. The plants also can adsorb some harmful gases such as nitrogen oxides, ammonia and chlorine inside buildings. As a result, the indoor and outdoor air quality of human living environment can be obviously improved with dust retention, noise reduction, improvement of indoor air quality and mitigation of heat island effect[2]. On the other hand, the ecological planting roof has good effects on heat-preservation and heat-insulation, and it can replace the way and function of the air conditioning system to adjust the indoor temperature by effectively reducing the heat, electricity consumption and average carbon dioxide emissions of indoor air conditioners in summer, indirectly protecting the environment and saving energy.

2.2 Protecting the roof structure of buildingAt present，most of building roofs are made of concrete in China. The concrete roofs have many advantages such as firmness, while small cracks will easily be formed on the surface of ordinary concrete which is exposed to the weather after a long period. The cracks will cause permanent damage to the building roofs, which will affect the stability of the roof structure. Planting on the roof will not only reduce the cracks caused by aging and stress produced by thermal expansion and cold contraction due to the temperature difference between freezing winter and sultry summer, but also protect the building structural layer from corrosion and weathering by absorbing solar radiation and ultraviolet rays, improving the thermal coefficient of resistance of the building roof and enhancing the thermal insulation of the roof owing to the water storage capacity of the planting roof.

2.3 Improving the storage and drainage capacity of the roof

Most planting roofs in China only have functions of drainage and beauty, but no function of water storage, so that the drained rainwater cannot be effectively collected and used. It is undoubtedly a huge waste of resources for China, which is very short of water. While the design of the planting roof with both storage and drainage functions provides an available solution. According to some researches, the loss of rainwater will be directly reduced by 70%-90%, because the stems and leaves of plants can store a large amount of rainwater quickly due to its absorption function[3]. The rainwater absorbed by plants will be reused in the water circulation system because of the transpiration of plants[3]. In addition, the water storage and absorption function of plants can effectively relieve the pressure on urban drainage systems. Whenever a storm comes, some roofs of urban buildings will be under tremendous pressure when the rainwater cannot be drained in time due to the small number and the small diameter of drainage pipes on their roofs. The storage and drainage capacity will be improved if the rainwater can be stored with the reduction of drainage. Thus the pressure on the drainage systems of the roof will be greatly reduced. The planting roof also has the function of purifying water resources. The pollutants in the rainwater are intercepted on the planting floor of the building roof by plants after filtering and purifying in the drainage pipes of plants, then the problems of water pollution in cities will be alleviated when the filtered rainwater and pollutants are discharged in time through drainage pipes of buildings.

2.4 Saving cost and energyOn account of the backward technology of automatic management, most planting roofs in China are in the manual management, which costs a lot of manpower and material resources, and death of plants can occur without precise irrigation. The ecological roof with intelligent plant management system can not only use the traditional electric energy as the driving energy, but also collect solar energy with solar panels to achieve the goal of right-time and accurate-quantity automated irrigation and fertilization. At the same time, it can constantly monitor the growth of green plants in order to find problems of plants in time and provide intelligent diagnosis and relevant opinions for users. This intelligent management system also has function of intelligent drainage. The drainage management system monitors the changes in the water level of the ecological roof in real time with the intelligent sensor. The automatic and intelligent drainage system will work to protect water resources once the sensor water level is too high. Instead of the manual management, the intelligent management system effectively solves many problems for the ecological roof, such as the fertilization and management of plants, so that a lot of manpower, time and electrical energy will be saved, and the management of ecological roof will be more efficient and accurate.

3 Requirements for the design of the ecological roof

3.1 Economy, practicality and strong operabilityThe costs of the design of the intelligent ecological roof should be as low as possible in consideration of the economic affordability of users. Of course, the requirements from users within the scope of safety standards should be met as much as possible if they have their own ideas. Besides, as a new product, the intelligent ecological roof should be designed with practicality and durability to ensure the intelligent and ecological function. In consideration of the customers from all walks of life, the operation methods of the intelligent management system should be simplified as much as possible in the design to make it operable, simple and convenient.

3.2 Safety of the roof load-bearingThe roof load is the main horizontal support and load-bearing component of a building. The safety of the roof load-bearing must be taken into consideration in the design of the intelligent ecological roof, including the load-bearing capacity and the conformity with national standards of safety production quality. The building loads that need to be considered mainly include all the loads of the ecological roof, plants, soil for planting, machines, drainage layer, waterproof layer, and heat-insulation layer,etc.[4], and some extra loads in special cases need to be considered in detail, such as the increased loads from rainwater caused by inadequate drainage in typhoons and rainstorms, and from plants growth on the roof. So light-weight building materials should be chosen whenever possible when designing the ecological roof. Before carrying out the architectural design, all relevant quality indicators and technical information of the ecological building should be thoroughly surveyed in advance. According to the height and the load-bearing capacity of the ecological roof, the loads of all eco-construction materials of the building, including loads in some special cases, will be calculated to ensure the normal progress of the ecological roof design and construction, and the safety of the eco-building loads.

3.3 Waterproof and drainageThe root puncture of plants will seriously damage the structure of roof water-proof layer and affect the roof waterproof and drainage[5].Therefore, the safety of the waterproof system structure is extremely important in the design of the intelligent ecological roof waterproof system. When designing and selecting ecological waterproof materials for the roof, people should try to choose some waterproof materials that have strong water resistance, corrosion resistance, mildew resistance and good scalability. Some ecological waterproof materials that have the function of secondary waterproof and reduce the ability of root puncture of plants can be chosen, and then,the secondary waterproof processing on the basis of the waterproof layer of the original ecological roof should be done. In case of heavy rain, the drainage system of the roof will not be able to withstand the pressure of double-position drainage, which may directly lead to the delayed discharge of rainwater, resulting in the accumulation of rainwater on the roof. Meanwhile, some plants, such as dead branches or fallen leaves, are liable to block the drain for the reason of the rainfall, and the roof drainage system will be destroyed if the rainfall cannot be drained in a short time. As a result, the diameter of the drainage pipes can be designed as large as possible, or more small drainage outlets can be designed in the design of drainage pipes for intelligent ecological building roofs. In addition, the harmful sundries, such as the branches and leaves of plants or silt on the surface of plants, should be effectively prevented from flowing into the drainage pipes of the building, so that rainwater can be discharged smoothly in time.

3.4 WindproofWhen designing the intelligent ecological roof, the windproof performance of the roof, large facilities and plants should be predicted, especially in areas with severe wind disasters in China, such as the coastal areas in Guangdong, Fujian, and Zhejiang. If the building roof cannot meet the requirements for the windproof safety, the roof, or plants and facilities on the roof may be damaged by the wind. Therefore, when selecting planting plants, people should choose shallow-rooted or ground-covering plants instead of large plants, such as arbors and large shrubs. At the same time, when planting green plants, the planting place should be at a certain distance from the side wall, preferably not less than 2 m, so that the plants will not be blown out of the wall to ensure personal safety.

4 Research on the design of the ecological roof based on intelligent management system

4.1 Dual-energy drivingIntelligent management system equips the building with solar panels. When the solar energy is sufficient, the solar energy is directly absorbed by the solar panels and then converted into electrical energy, which provides sufficient energy for the normal operation and maintenance of the intelligent management system, and the surplus energy can power the buildings. While, when the solar energy is insufficient, the intelligent management system usually automatically adjusts itself to the electrical mode for driving to keep the system work smoothly and normally.

4.2 Precise irrigation and intelligent DrainageIntelligent management system collects the environmental humidity information of the planting roof with a humidity sensor installed on the roof, and constantly controls the environmental humidity in a certain range. When the humidity is too low or the soil humidity is insufficient, the system will send a message to remind the user, and automatically select the proper irrigation methods, such as sprinkler, drip or infiltration, according to the actual situation and the set control programs, to ensure that the plants have sufficient water. When a rainstorm comes, if the water level is too high, the system will automatically open the valve to allow rainwater to flow smoothly from the drainage pipes to prevent rainwater from accumulating and affecting the roof drainage.

4.3 Real-time and remote monitoringUsers will obtain the information of environmental parameters such as air temperature, humidity, light intensity, concentration of harmful chemical gases with the intelligent environmental sensors which are installed on the roof of the building. Real-time monitoring of the internal environment of the roof will be achieved with analyzing and integrating by the roof system control management center. If something goes wrong with the planting roof, the system control center will automatically send out an message to warn the users, diagnose the problems of the user devices and give corresponding solutions in time with the users’ permission. Certainly, they can also be set to "Automatic" directly. In addition to real-time function, the system also has a remote control function. It means that users can log in to the system control center with mobile phones or computers to remotely control the intelligent management system. If users think it necessary to water and fertilize the plants, they can do it through the remote control system.

5 Conclusions

The ecological roof based on intelligent management system plays an important role in improving the ecological environment of the city, protecting the roof structure of the building, improving the capacity of water storage and drainage of the roof, and saving costs and energy. With full consideration of the requirements for the ecological roof design, this paper makes an in-depth discussion about the ecological roof on the basis of intelligent management technology to provide a reference for the future ecological roof design.