I. Project Background
"Strategic Design for Eco-efficiency" was developed by American eco-architect William McDonald. McDonough (WilliamMcDonough) and his partners *** with the completion of a new campus of the University of California, Davis, U.S. planning and design projects, aimed at nearly 7,000 freshmen, faculty and staff to create an ecological and comfortable living environment, won the 2004 ASLA professional awards. Against the backdrop of the 2001 California energy crisis, energy conservation was a key focus of the project. Based on the statistical comparison of the annual average solar radiation of some cities in the U.S. (e.g., 3.67kWh/m2?d in Seattle, Washington, and 3.99kWh/m2?d in Fairbanks, Alaska), the designers believed that the city of Davis (5.10kWh/m2?d) had superior solar energy resources, and therefore incorporated the use of solar photovoltaic systems into the planning and design of the project.
Second, the project planning
1. Architectural planning
(1) the planning of the building direction of the planning of the building direction to the east 10 degrees (Figure 1, grid representation), not only to ensure that the south side of the light, to meet the needs of the residents of the light in the winter time, but also to reduce the building of the afternoon sun in summer to reduce the absorption of heat, slowing down the fluctuation of the room temperature. In addition, the afternoon wind passes through the area from the south and southwest in summer, providing opportunities for natural cooling, while in winter the wind is dispersed and attenuated when it enters from the south due to the obstruction of the building wall to the northwest (indicated by the wavy line in Figure 1). The water flowing through the area is then directed to the more shaded north and northeast to make up for the lack of wind by cooling through evaporation, while also avoiding excessive evaporation of the water body. (2) The height of buildings in the planning area is determined by the winter sunshine, and it should be ensured that the shadows of the buildings do not cover the streets completely in winter. In summer, the southern and western parts of the building have strong solar radiation, and this area can be slowed down by the use of special building materials to reduce the fluctuation of indoor temperature, and appropriately equipped with some deciduous trees to provide shade for the building; the large-scale courtyard surrounded by a group of buildings can capture the wind vortex (represented by the ring in Fig. 2), and the plants carefully equipped with the courtyard are used to divert the breeze. (3) Expansion of architectural space Maintaining and enhancing the comfort of the microclimate of the outdoor space through careful design can stimulate the use of the environment and increase the amount of time people spend outdoors, thereby reducing the energy consumption of the building. As shown in Figure 3, the roof space and vertical space of the building can be optimized to form usable private or public **** outdoor space, and the area of outdoor space can be further expanded by setting up an underground parking lot; the formation of an open space inside the building not only improves the building's lighting and ventilation conditions, but also provides a more comfortable sitting space for the residents.
2. Architectural monolithic design
The designer's ideal architectural monolith is shown in Figure 4. Material: large windows are installed in the south of the building to increase light; building materials that can absorb and slowly release solar heat are used inside the building to collect solar energy; grass is planted on the top of the building to form a green roof. Equipment: Solar photovoltaic panels are applied to the open garage to collect and utilize solar energy while providing some shading; solar water heaters are used to reduce energy consumption; and radiant floor heating is used inside the building to create an indoor space with a suitable temperature. Installation: set up movable sunshade on the upper part of the south-facing windows to meet the different needs for sunlight in different seasons and time periods; set up push-pull ventilators on the top of the building to increase air flow. In addition, the south side of the building should be reasonably equipped with some deciduous tree species to meet the needs of the residents of summer shade, winter lighting.
3. Ecological Measures
Figure 5 shows the ecological measures involved in the architectural planning. In addition to the use of solar photovoltaic panels on top of the building and the planting of turf mentioned in the previous section, the designer also proposes the use of permeable paving within the building clusters and the installation of grass pools with waste treatment systems, and vegetation depressions with advanced water-saving technologies to enhance the control of rainwater on the site. The planting of plants requires the use of adaptable, easy to manage native tree species, which is also nowadays emphasized in ecological gardens.
III. Energy-saving Measures Adopted in the Project
1. Heating Measures
(1) The geothermal system is different from the air temperature that shows obvious fluctuations with the seasons, the underground temperature is relatively constant. In summer, the heat released from the building is absorbed by the circulating pipeline and then transferred to the earth; in winter, the circulating pipeline absorbs heat from the earth and then transfers it to the floor and the building for heating. Geothermal systems are usually designed to meet all of a building's cooling needs, as well as 80% to 100% of its heating needs, drastically reducing energy consumption for HVAC (indoor or automotive heating, ventilation, and air conditioning systems or related equipment), which is highly efficient and energy-saving; and it is not easy to cause dirty air convection, which maintains clean indoor air, making it the most comfortable and healthy way to heat a home. However, due to the long duration of the Davis cold season, the "heating" of the geothermal system is likely to extend to the surrounding environment, thus reducing the effectiveness of the system until the end of the winter season, so care needs to be taken to alleviate this problem in the application process. (2) Heat pumps provide the most energy-efficient heating and cooling strategy for many applications through the use of renewable heat sources such as geothermal. They have good conversion rates and can reduce energy consumption as well as emissions of pollutant gases such as carbon dioxide. However, because the performance of the heat pump is highly dependent on the nature of the heat source, in the case of unstable heat source also need other auxiliary equipment, and the cost is more expensive, so the actual application needs to be selected according to the capacity of the power distribution network, the best heat source close to the heat load (such as student dormitories) to reduce transmission and distribution costs, to achieve the optimal use of efficiency.
2. Cooling measures
(1) plant cooling green plants can not only form a cool and comfortable visual landscape in the summer, but also has a cooling effect to provide shade, improve air quality, and alleviate the maximum summer temperature. In this project, the designer mainly elaborates and analyzes from two aspects: ground greening and roof greening. For ground-level greening, the study simulated a 30% (3 trees per home) increase in ground-level tree cover in Sacramento, California, and showed a year-round energy savings of about 30% for cooling. In the case of green roofs, summer air temperatures can raise the surface temperature of a gravel roof to 140°C to 175°C, whereas a green roof would not exceed 77°C under the same conditions, which would significantly reduce cooling energy consumption; in addition, while conventional roof structures begin to deteriorate after 20 years, green roofs slow down the deterioration to 35 years by reducing the fluctuation of daily and annual temperatures, prolonging the This extends the service life of the house while reducing maintenance and replacement costs. Of course, plant cooling also has certain limitations, for example, the maintenance of trees has certain technical and cost requirements; in addition, the growth of trees requires sunlight, which also has certain limitations on the use of solar photovoltaic panels. (2) Ventilation and cooling ventilation can be divided into natural ventilation and mechanical devices (such as fans) ventilation. Natural ventilation is generated by temperature differences between the interior and exterior of a space, or pressure differences driven by the sides of a building. To promote cross-ventilation, ventilation holes or operable windows should be provided on opposite sides of a building, and large obstacles (e.g., walls) between the two should be avoided; in multi-unit complexes, a residential unit often has only one face that can be connected to the outside, in which case an "air duct" at the top of the building can also promote air circulation in the internal space (Figure 4) In this case, an "air duct" at the top of the building can also promote air circulation in the interior space (Figure 6). Surveys have shown that the use of electrical equipment such as fans to ventilate indoor spaces accounts for a significant portion of a household's annual energy consumption. In this project, it was recommended that electrical equipment not be used or only be used during the hottest part of the summer and the coldest part of the winter, and that the rest of the year be naturally ventilated by push-pull fans (wind-powered) to minimize the use of electrical equipment as much as possible. It should be noted that in Davis, summer nighttime temperatures are usually much lower during the day, and nighttime cooling times should be controlled to avoid over-cooling of heating equipment, which leads to additional energy consumption.
3. Wastewater and Stormwater Treatment Measures
The project mainly uses artificial wetlands to treat and utilize wastewater and stormwater, and proposes four basic applications: First, a shallow marsh system, based on a fairly large watershed area (usually more than 1.67ha), which requires a significant amount of space and a stable supply of baseflow or groundwater to support newly planted wetland plants; second, a pond wetland system, which consists of a ponded wetland system, which includes an area with a large pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, a pond, and a pond. Ponded wetland systems, which include a pond area and a shallow marsh area where the pond slows the rate of incoming runoff flow, pools sediment and removes pollutants (this system requires less space and is considered to be the most stable system); iii) Extended detention wetlands, which have a temporary runoff storage function that reduces the amount of space occupied by the wetland; and iv) Pocket wetlands, which are suitable for sites that do not have a stabilized source of baseflow, smaller sites with frequent water level fluctuations, and are best suited for arid conditions (not easily monitored and unstable compared to other systems). Considering the low annual rainfall in Davis, as well as sanitation and odor concerns, the wetlands are recommended to be sited on sites with wastewater treatment systems.
Fourth, the application of China's current situation and inspiration
The deterioration of the climate brought about by environmental pollution makes people rely too much on electrical equipment to obtain a suitable indoor climate environment, which results in a large amount of energy consumption and even the emission of pollutant gases, which in turn aggravates the deterioration of the climate, forming a serious vicious circle. As one of the pillar industries of China's national economy, energy saving and emission reduction in the construction industry has attracted the attention and research of many scholars in China, and the ecological concepts and ecological measures put forward in the "eco-efficiency strategic design" project have been applied and developed to varying degrees in China.
1. Solar photovoltaic
Building energy consumption is mainly generated by the construction of the building energy consumption and the use of energy consumption. In modern cities, building energy consumption accounts for a large proportion of all energy consumption in human activities, with the electricity consumed in the process of building use being the most important. Taienergy photovoltaic power generation system can directly convert clean and renewable solar energy into electricity, which can reduce the electricity consumption of buildings to a certain extent, and there have been some cases of applying it to buildings in China. By the Southeast University School of Architecture, Southeast University Architectural Design and Research Institute and the Department of Industrial Ecology of the Royal Swedish Institute of Technology jointly designed the China Putian Information Industry Shanghai Industrial Park intelligent ecological office building, which is installed on the roof of the building 10kW experimental solar photovoltaic cells, which can generate electricity accounting for 4% of the total electricity consumption of the building, mainly used for the lighting of the building fa?ade and the charging of the EPS system. However, due to cost and other issues, the application of solar photovoltaic buildings in the country is still in the exploratory stage, and the future development is still dependent on the improvement of technology and government support.
2. Green Roofs
Compared to solar PV systems, green roofs are more popular in China. With the development of society and the progress of science and technology, today's green roofs are not only limited to laying turf on the top of the building so simple, but also planting all kinds of flowers and trees, placing sketches and facilities to create a comfortable and pleasant "air garden", and also cultivating all kinds of vegetables to form an interesting "air farm" or as an educational base, which can be used as an educational base. It can also cultivate various vegetables to form a "sky farm" with the interest of farming or serve as an educational base, and the utilization of the roof of the building can be said to be the ultimate. By the World Roof Greening Association awarded the "World Roof Greening Research and Teaching Demonstration Base" title of Nanjing Zidong International Creative Park, the roof of all the buildings in the park are planned for the construction of roof gardens or air farms, to achieve 100% rooftop greening for the air farms in the planting of vegetables do not use pesticides, chemical fertilizers, the output of organic Vegetables grown in the air farm do not use pesticides and chemical fertilizers, and the output of organic vegetables is supplied to the canteen of the park. In the relevant policies, norms to promote the construction of rooftop gardens in China, Beijing, Guangzhou, Shanghai and other large cities have begun to take shape, small and medium-sized cities still need the government's active publicity and guidance.
3. Artificial wetlands
Artificial wetlands, this new type of sewage treatment measures in China, although the late start, but the rapid development, both theoretical and practical aspects have achieved certain results. In 2006 Shenyang World Horticultural Expo Environmental Protection Park, 2008 for the Beijing Olympic Games and the Beijing Olympic Forest Park and 2010 Shanghai World Expo Park, the back of the beach park and other three large-scale international events held in the park have artificial wetland wastewater treatment technology applications. Among them, Beijing Olympic Forest Park is the first large-scale urban park in China that fully supplies water to the park's water system and main landscape water. The total area of the artificial wetland park in the south park is 41,500m2, and the area of the wetland oxidation pond is 30,500m2, which adopts the patented technology of "Compound Vertical Flow Artificial Wetland" independently developed by the Institute of Aquatic Biology of the Chinese Academy of Sciences, and it can treat 2,600m3 of recycled water from the Qinghe Sewage Treatment Plant and 20,000m3 of recycled water from the main lake of the park every day. It can treat 2600m3 recycled water from Qinghe Sewage Treatment Plant and 20000m3 recycled water from the main lake of the park every day, and plant more than 10 kinds of aquatic plants such as cattail, water onion, reed, Chichibu, calamus, etc., which can purify the water quality and at the same time create a good landscape environment. It should be noted that, although the artificial wetland has many benefits, but can not completely replace the natural wetland, we vigorously research and development at the same time should comply with the laws of nature, and actively protect the earth's "natural kidney".
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