Bioclimatic Design Approach Integration into Architectural Design: a Library Case Study

Transcription

1 PLEA 2016 Los Angeles - 36 th International Conference on Passive and Low Energy Architecture. Cities, Buildings, People: Towards Regenerative Environments Bioclimatic Design Approach Integration into Architectural Design: a Library Case Study WEI ZHU 1, ZHUO WANG 2 1 Xi an University of Architecture and Technology, Xi an, China 2 China Northwest Architecture Design and Research Institute CO.LTD, Xi an, China ABSTRACT: It is very common for architects to consider spatial design as a top priority in the early design stage, but leave the building performance issues to engineers afterward. Recently, many architects have realized that considering the internal environmental performance in the first stage of design would reduce energy consumption and create a more comfortable living environment. However, it is often confusing for designers to involve the integrated environmental design while creating a building form and space in the early design stage in practice. The bioclimatic design approach could be simply described that architecture design methods could take advantage of the climate through the right application of design elements and building technology to energy saving as well as to ensure comfortable conditions into buildings (Olgyay,1973). This study describes the process of applying bioclimatic design approach within the design of a library in Xian, China. More specific, it is a project of transformed an old industry building into a library. The original structure is kept and the design process focuses on achieving high environmental performance in the library based on an understanding of seasonal and diurnal climatic variations. In detail, the spatial design can be intervened by the solar geometry to maximize daylighting application. Thermal performance could be improved by integrating a natural ventilation strategy and an appropriate material choice within the design of building form and space. The conclusions are draw from the performance prediction by a series of dynamic computational simulations. This paper demonstrate that bioclimatic design approach may be a choice to create an appropriate building form and space and a comfortable and energy efficient environment in the early design stage. Keywords: bioclimatic design approach, internal environmental performance, library design INTRODUCTION The bioclimatic design approach could be simply described as architecture design methods that take advantage of the climate through the right application of design elements and building technology for energy savings, as well as to ensure comfortable conditions in buildings (Olgyay, 1973). It is very common for architects to consider spatial design as a top priority in the early design stage, but leave the building performance issues to engineers afterward. Recently, many architects have realized that considering the internal environmental performance in the first stage of design would reduce energy consumption and create a more comfortable living environment. However, it is often confusing for designers to involve the integrated environmental design while creating a building form and space in the early design stage in practice. It is discussed the main reasons why so many architects do not integrate the bioclimatic approach into their designs. One of the main reasons is their lack of confidence. Some of them believe that integrating bioclimatic design requires significant knowledge of green technology. Others finish the design through the ordinary process first, and then pass the whole scheme to the engineers. Therefore, a general bioclimatic design process might offer the architects easy access to a bioclimatic design area. (Maciel et al. 2007) RESEARCH OBJECTIVE AND PURPOSE The main questions of this research are: What is the early stage design process for the bioclimatic design approach? How is each stage managed? Could this method be applied to all architecture types? This study discusses whether a general design process for bioclimatic design approach exists and of what it comprises. Then a library design process of applying bioclimatic design approach is described, in order to find the essence and the problems of the proposed process. Hawkes, McDonald, and Steemers (2002) presented the Vitruvian Tripartite Model of Environment (Fig. 1) in their important book The Selective Environment. This model is first mentioned in Vitruvius s De architectura. It discussed the main function of architecture is to be the mediation between climate and comfort.

2 PLEA2016 Los Angeles - Cities, Buildings, People: Towards Regenerative Environments, July, 2016 also considered when analyzing the site. In addition, they tend to only consider the general situations of the climate and pay attention to the influence mentioned in code. In bioclimatic design, a climate analysis needs to be described both qualitatively and quantitatively. Figure1: Vitruvian Tripartite Model of Environment Source: Hawkes et al. (2002) However, with the development of architecture, environmental performance is not the only purpose the architects seek to fulfill, as spatial performance is becoming more and more significant. Modern architects tend to create spaces first, but then leave the environmental issues to engineers. In the mainstream design method in China, climate condition will only be considered because of codes. More specific, the majority of architects will not consider about what the climate may influence the design at the early stage. They consider it sometimes only because some code has compulsive requirements. It often happens at the last stage when the main design has been delivered, and the job tends to be left to engineering. According to the bioclimatic design approach, spatial requirements and environmental requirements are not opposite or mutually exclusive. Space and form of a building can be tools to increase environmental performance. In addition, the choice of materials and construction type not only serves the aesthetics of the buildings, but also the internal environment. (Fig. 2) Figure 2: model of bioclimatic architecture design Source: Author BIOCLIMATIC DESIGN PROCESS A global process Generally, a bioclimatic building design begins with a description of the climate at its location (Hawkes et al. 2002,13). This is a large difference between the bioclimatic approach and general design. Most architects will first analyze the site and brief, though climate is Additionally, a detailed requirement analysis is needed during this stage as well. This requirement analysis includes both spatial and environmental analysis. First, the users need to be identified, by means such as their gender, age, and occupation. Second, it is useful to make a detailed schedule of all activities, accounting for the number of users participating in each, the composition of the group, and the times at which each activity may occur. (Hawkes et al. 2002) The source analysis is basically climate and site analysis. Some issues in both climate and site analyses could actually be sources to satisfy the requirements. For this reason, analysis is reinforced as the first step for meeting the global process requirements (Fig. 3). For example, the architects could easily notice that the internal heat gain of a group of people could be a passive heating source. Local materials could be considered when choosing materials. The next step is matching the first two analyses, which is the key from analysis to design. Advantages and disadvantages of the site and climate for achieving the requirements could be found. In detail, the spatial design can be intervened by the solar geometry to maximize the daylighting applications. Thermal performance could be improved upon by integrating a natural ventilation strategy and appropriate material choice within the design of building form and space. The schedule of the activities could be matched with the schedule of sunlight illuminating into the buildings, and the architects could allow or avoid it according to the requirements analysis. The key point is that the architects could find evidence from the analysis in advance when making each decision. After the analysis, architects could make decisions about the building form, the orientation, the fenestration, and the materials choice of façade. Then, some simulations could be made to test the decision. In fact, these design strategies would not be wrong because a series of analyses have been done in advance. But the simulations could help in design modifications, such as the size of windows. It is noticed that these two steps could be repeated several times until the goals are reached. Case study To begin, a brief of the project will be introduced. The existing building is an old factory in Xi'an, China. This building is located in a factory campus, which belonged

3 to a steel-manufacturing group. After the steelmanufacturing group moved, 11 old factory buildings remained in this area. In 2004, an art university bought and transformed some structures into teaching buildings and student apartments. Therefore, this building is being designed Figure 3: Global design process of bioclimatic approach Source: Author into a small but multi-functional library for both the art students and the public. The existing building is around 26mX38m, with a 9.9m height at the highest point. The brief required book-storing areas, reading areas, a small cafe, and a gallery. It should be noticed that a gallery is not usually included in a library's brief. But in this project, a gallery is needed for presenting works of art, including paintings and handicrafts. Therefore, as it will be a multi-function library, the requirements of different areas can vary. Requirements analysis As Table 1 shows, it could be seen that in different areas, both environmental and spatial requirements are different. In this stage, the requirement analysis is carried on from both qualitative and quantitative aspects. People's activities in different areas determine the requirements. More specific, selecting books is the main activity that will occur in storing areas. To finish this activity, the basic space size should be enough for people to stand in front of the bookshelves. The light should also be appropriate for reading books on the bookshelves. In addition, it can be noticed that storing areas are used not just for people, but also for the books. Therefore, the environmental requirements are for the books as well, which are even given a higher priority. It is important to avoid the books being exposed to direct sunlight. Compared to storing areas, in reading areas, people tend to stay much longer and need space to sit. It also includes private reading areas and group reading areas. These two areas need to be separate. In terms of the gallery, people need space to enjoy the artworks. For the gallery, the artworks do not welcome direct sunlight, but need enough light to be properly presented. Comparing these three areas, the environmental requirements have different levels. The reading areas where occupants would stay much longer tend to need better physical environment, including enough daylight, appropriate thermal environment and quiet spaces. By contrast, selecting books short duration, therefore, the level of environmental requirements is lower than reading areas. The gallery has specific requirements that are not just for people but also for the artworks presenting. The internal environmental is to emerge the artworks appropriately. In this way, the daylighting design should be prior. Table 1: Requirement analysis Activity Temporal Spatial Environmental level Selecting books 30 mins standing Reading books over 2 hours sitting Enjoying artworks flexible standing Climate analysis

4 From the Monthly Diurnal average chart in Xian, it should be noticed that summers and winters are very clear. (Fig. 4) During the daytime in mid-seasons, the temperature also may be above the comfort zone; the occupant time will mostly be during the daytime. Therefore, in these periods, natural ventilation is important. In summers, the maximum temperature is above the comfort zone, but in winters, even the maximum temperature is below the comfort zone. In this case, both cooling and heating are important factors. So, one of the goals of this project is to reduce the length of heating and cooling periods, according to this analysis. Figure 6: The daylight factor of the existing building Source: Author MONTHLY DIURNAL AVERAGES - Xian, CHN 癈 W/ m? k wint er k summer wint er k k 0 0.2k k Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 4: Monthly Diurnal average chart Source: Ecotect weather tool Site analysis & existing building analysis The Fig. 5 shows the orientation of the existing building. No windows are located on the south and north facades, and some small windows exist on the high level of the west façade. On the east façade, both small size windows at high level and large size windows at low level are present. Strategies and design modification Followed the analysis above, several strategies have been decided: First, the entire building is designed to be two stories tall, because the height is 10 metres. In this way, an atrium is added for the daylighting and ventilation on the ground floor. The place of atrium follows the position of the existing skylight. The openings in the atrium can be controlled seasonally. In summers, the temperature outside is extremely high, and the openings can be fully opened, helping to lower the temperature inside. In the winters, the outside temperature is low, and it is not possible to open windows for ventilation. However, the library could be crowded and natural ventilation is needed during both summer and winter. Therefore, the atrium could be used for pre-heating the fresh air. (Fig. 7) Figure 7: Stack effect Source: Author Figure 5: The existing building Source: Author The purpose of a daylight factor simulation on the working plane (Fig. 6) is to analyze the daylighting performance of the existing building. This helps to determine the layout and the fenestration. According to the result, it could be seen that the daylight factor on north part and the west part is below 2%, but over 10% on the east part, which means the large size windows might cause a glare. In addition, in the centre of the plan, the daylight factor is satisfactory, given the benefits from the skylight and high windows. Second, the layout could be determined according to the requirements. The reading areas are placed on the first floor and in the centre of the plan. In this way, this area can enjoy uniform daylight, a benefit that is brought by the skylight. The gallery is placed on the northern and western wall where only some high windows exist. The book-storing area is placed in the centre of the plan on the ground floor, and the atrium can provide enough daylight and natural ventilation as well. (Fig. 8)

5 modified according to the simulation result. This step is not presented in details in this paper because the project is in process and there will be a further paper to discuss this stage individually. Take daylight simulation of reading areas on the first floor as an example, the daylight factor simulation shows the reading areas have enough daylight (Fig. 10). In addition, the sunlight would not affect the reading areas on winter solstice when the sun angle is the lowest in the whole year. Therefore, it could be deduced that the direct sunlight would not reach the reading areas in the whole year (Fig. 11). Figure 8: Layout of new building Source: Author In addition, according to the analysis, the fenestration can also be decided. In the existing building, no windows are on the southern façade. But it could be a good option to design a large sized window on the southern façade with a carefully designed shading device. This would allow the winter sun but stop the summer sun; in addition, the size and position of the window is designed according to the sun-path diagram. This can help calculate the perfect position of the window (Fig. 9). In the summer, the hot sunlight is stopped but in winter, the warm sunlight is allowed; it would not influence the reading areas on the first floor, because the edge of this area is determined by the position of the sun at 12pm on winter solstice. N Figure 10: daylight factor simulation of reading areas Source: Author Lastly, the floor materials where the sunlight could reach during the winter could consist of dark colours and high thermal mass materials. Figure 11: sunlight on winter solstice through south facade Source: Author Figure 9: Strategy on south facade Source: Author After the strategies decided, next step should be test the effectiveness of all the strategies. Both of computer simulation and physical models simulation could be useful in this stage. Generally speaking, this step is a long process because all the strategies need to be tested individually. And the design decision would be kept or DISSCUSSION This case study follows the design process proposed in this paper. In the process of design, the first two stages, requirements and sources analyses, play a major role in gaining the basic concept and strategies. Some people might believe all design processes are started from analysis; but not all processes make such a deep analysis, including temporally and spatially, qualitatively and quantitatively. The deeper the analysis goes, the more design inspirations come in the design

6 step. It also needs to be noticed that this decision is not the only option. The strategies can utilize creative and extraordinary ideas. Different architects may propose various strategies that could achieve similar environmental requirements, but gain diverse spatial performance. 3.Olgyay, V. (1973). Design with climate: bioclimatic approach to architectural regionalism: Princeton University Press. In addition, this process is for the early design stage, after the concept and strategies are proposed many detailed works follow. Taking this case study as an example, the size of the atrium needs to be determined. Although the space layout has been decided, the spatial organization needs to be further designed. CONCLUSION In conclusion, this paper proposes a basic bioclimatic design process for architects who want to integrate a bioclimatic approach into their design. It is true that architectural design is a complex process, and many issues need to be considered, such as history and culture. But it will not be against that environmental and spatial requirements are basic needs for a building, especially the buildings' types are for people used frequently, like educational buildings, offices and residential architecture. In terms of further research, first, this design process graph could be a basic series of steps in the early design stage, in which additional processes or detailed processes can be expanded. For example, in the presented case, the existing building analysis is one important part in the site analysis stage, but the new construction does not require this analysis. Second, this is a general process for all building types but there should be differences between different building types. Therefore, some specific processes focusing on some building type could be further research. In addition, it should be noticed by architects that every single step has many opportunities to make the final design product attractive, comfortable, and energy-efficient. ACKNOWLEDGEMENTS This project is supported by the National Science & Technology Pillar Program during the 12th Five-year Plan Period. (Grand No.2014BAL06B04) REFERENCES 1.Hawkes, D., McDonald, J., & Steemers, K. (2002). The selective environment: Taylor & Francis. 2.Maeiel, A. A., Ford, B., & Lamberts, R. (2007). Main influences on the design philosophy and knowledge basis to bioclimatic integration into architectural design-: The example of best practices. Building and environment, 42(10),