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Ecological renovation process of Nanjing’s housing stock built between 1840 and 1949, China Ecological renovation process of Nanjing’s housing stock built between 1840 and 1949, China
Wu, Jinxiu; Dong, Wei; Li, Yonghui; Fu, Xiuzhang
2020-05-03 00:00:00
JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 2020, VOL. 19, NO. 3, 254–263 https://doi.org/10.1080/13467581.2020.1724542 ARCHITECTURAL PLANNING AND DESIGN Ecological renovation process of Nanjing’s housing stock built between 1840 and 1949, China Jinxiu Wu, Wei Dong, Yonghui Li and Xiuzhang Fu School of Architecture, Southeast University, Nanjing, China ABSTRACT ARTICLE HISTORY Received 20 June 2019 Numerous in number and mostly still in use, buildings built between 1840 and 1949 are Accepted 5 January 2020 valuable assets in the rapid development and renovation of Chinese cities. However, due to lack of maintenance and being inhabited mainly by the elderly and people with low incomes, KEYWORDS many of these buildings are in poor condition and have much higher possibilities of being Ecological renovation; demolished. The objectives of ecological renovation presented in this paper are to improve housing Stock built between building performance and to achieve higher levels of comfort and lower levels of energy 1840 and 1949; higher Levels consumption. The housings in Zhong-nong-li block in Nanjing are used as an example in this of Comfort; basic Renovation; thorough paper to show how a strategy of “basic” renovation and “thorough” renovation is used in the Renovation ecological renovation of housing stock between 1840 and 1949 in China. The paper demon- strates that these are very practical steps for this building stock in China and could not only help to balance social and economic factors in practice, but also improve the living conditions of the residents, and endow the old houses with a new, long life. Numerical simulations of the natural day lighting and ventilation situations before and after renovation are made to show the improvement in building performance after renovation. 1. Introduction and 4), leading to the situation of high levels of energy consumption and low levels of comfort. With the rapid 1.1. The background and purpose of the research renovation of Chinese cities, poor building conditions Located in the delta economic zone of Yangtze River, and performance are usually the main reasons for Nanjing has always been one of most important cities in buildings (even whole blocks) to be demolished. At China. With an urban population of 8.16 million (2013) the same time, because the inhabitants are mainly (Jiangsu development & reform commission 2014), elderly and people with low incomes, this situation Nanjing is the second largest commercial center in east- not only threatens the protection of these buildings, ern China, after Shanghai. It has been ranked at the but also affects the health of the occupants. fourth place by Forbes magazine in its listing of “2008 Therefore, ecological renovation is crucial for Top 100 Business Cities in Mainland China”, and also was improving building performance so as to provide inha- awarded the title of 2008 Habitat Scroll of Honor of bitants with living environments that have a high level China, Special Award of UN Habitat Scroll of Honor of comfort and low energy consumption, and at the and National Civilization City (Nanjing morning news same time, preserve the invaluable cultural value of 2014). Nanjing was the capital of the Republic of China these buildings. (Dong and Wu 2011) The purpose of before the Chinese Civil War. It is renowned for buildings this paper is to explore ecological renovation methods built between 1840 (Opium War) and 1949 (establish- of the buildings built between 1840 and 1949 in China ment of People’s Republic of China) (Figures 1 and 2). so that they can better fulfill the need of current and This building stock in China is an important part of future life. Chinese modern architecture (1840–1949), symbolizing the crucial transition from traditional to modern archi- 1.2. Recent developments and current literature tecture in the history of Chinese architecture. Numerous in this field in number and mostly still in use, these buildings are valuable assets in the rapid development and renova- Ever since the UNESCO Nairobi Declaration in 1976 tion of Chinese cities (Feng and Lu 2003). and the Washington Charter of 1987 set out the Zhong-nong-li block lies in the downtown of need for the preservation of historic cities to be Nanjing. Most of the housing here was built in the integrated with development to make them Republic of China era (1911–1949). Due to being built “adapted to contemporary life”,significant progress very long ago and suffering from a lack of mainte- has been made in the study of historic building nance, the housing is in poor condition (Figures 3 conservation and renewal at home and abroad. CONTACT Jinxiu Wu 545833290@qq.com School of Architecture, Southeast University, No. 2 Sipailou Road, Nanjing, Jiangsu 210096, China © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of the Architectural Institute of Japan, Architectural Institute of Korea and Architectural Society of China. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 255 (1) Restoration of historical buildings As early as the 18th century, Western architects focused on the authenticity of restoration, based on historical information and the original style in order to continue the historical and cultural value of historical buildings. (2) Adaptive renovation and functional updating Adaptive renovation refers to the process of adapt- ing old buildings to new functions on the premise of preserving their historical characteristics. In 1977, the United States Secretary of the Interior formulated a standard for the restoration and adaptation of his- toric buildings (the standards for rehabilitation), which was later revised in 1990 and again in 1995. The stan- dard made restrictions on the possible new functions of buildings in order to minimize the influence of the renovation on the historical building (McNicholl and Lewis 1996). (3) Technical/ecological renovation and building performance improvement Figure 1. (Upper): Layout of housing stock between 1840 and 1949 in Nanjing and their most famous sample: Sun Yat-sen With sustainable development becoming a new Mausoleum. imperative, more and more attention is being paid to the improvement of building performance of old A great deal of research has been conducted, and buildings by technical/ecological renovation, espe- renovation projects implemented, providing the cially in the United States and Europe. In the United background for the research reported here. States, Harvard University is a good example for this. The research on the renovation of historical The “Green Campus Plan” has become an important buildings in architecture can be divided into three direction for future development of the university, with phases. a large number of projects appearing in recent years. Figure 2. (Upper): Layout of housing stock between 1840 and 1949 in Nanjing and their most famous sample: Sun Yat-sen Mausoleum. 256 J. WU ET AL. Figure 3. (Lower): Modern historic housing in the Zhongnongli and the typical situation. projects in Denmark, the ecological renovation of the Hedebygade community in Copenhagen successfully revitalized the neighborhood in the old city through ecological renovation. The project integrated a number of low-energy technologies, which not only provided a comfortable living environment for resi- dents through building performance improvement, but also achieved considerable energy-saving results (Jensen 2006). In China, increased attention has been put on reno- vation of historical buildings for the purpose of sus- tainable utilization. WU Zhiqiang and his team of Tongji University, applied foreign technologies in the exploration of ecological renovation of Wenyuan Building, Tongji University (Wu and Chen 2007). Professor LIU Shao-Yu of the University of Hong Kong and his team applied green building renewal technol- ogies in the renovation of News & Media Research Centre in the east wing of Eliot Hall, the University of Hong Kong (Liu 2007). In regard to quantitative evaluation of building eco- logical performance, the most successful system is the Leadership in Energy and Environmental Design (LEED) Figure 4. (Lower): Modern historic housing in the Zhongnongli green building rating system in the United States and the typical situation. (LEED-NC 2009). The green building evaluation system in China is divided into “Green Building Design Label” The author made a detailed research on Harvard’s and “Green Building Label” (Ministry of Housing and “Green Campus Plan” when acting as a visiting scholar Urban-Rural Development of the People’s Republic of at Harvard in 2007. (2019) China (MOHURD) 2014). Germany, France, the United Kingdom and other Northern European countries are taking a leading role in the research of sustainable development in the 2. Ecological renovation process of the renovation of historical buildings. The University of research project (methodology) Nottingham Jubilee (Jubilee Campus) is regarded as the milestone in Green Building (Hopkins Architects). The ecological renovation research in this paper Being one of the most remarkable green community focuses took the housing in the Zhong-nong-li block JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 257 as an example to show the process and methods of the are clarified. Then the performance standards were set design. The research used quantitative simulation and according to both renovation goals and strategies and analysis methods to provide effective and feasible building codes in China. Ecological renovation process ways, helpful to avoid unnecessary damages caused forms a two-way loop with quantitative simulation and by renovation unsupported by careful analysis. evaluation and performance standards. If the simula- tion & evaluation show the performance standards are fulfilled, the ecological renovation process is complete. 2.1. Contents and process of ecological Otherwise, further improvement and adjustment are renovation made to the design and also further simulation & evaluation will continue to make sure the effect of The ecological renovation process in this paper contains design until the performance standards are fulfilled. a number of steps: “Field investigation- Building perfor- mance evaluation- Renovation design-Summation- (3) Quantitative simulation and evaluation Design adjustment (if needed)”. The contents and pro- cess are as follows (Figure 5). Numerical animation and analysis software such as ECOTECT (Autodesk 2014) and CFD (2019) are used to (1) Field investigation and building perfor- make quantitative simulation of the real effects of mance evaluation ecological renovation process. Comparison is made between the effects of ecological renovation design To obtain information of the performance of the and the performance standards, enabling evaluation of buildings, we chose extreme climates both in winter the design effect and further improvement. Changes in and summer, adopting questionnaire and measurement the status of natural lighting and ventilation before methods to investigate and measure the selected build- and after renovation are compared to show the ings in the Zhong-nong-li. A total of 30 valid question- improvement in building performance. naires were collected and measuring was taken in seven consecutive days per quarter. The investigation included both the basic information and health condi- 3. Ecological renovation process: taking the tion of residents and the basic information and physical Zhong-nong-li project as an example condition of the buildings. Building performance was evaluated according to the data collected. Ecological renovation as discussed in this paper is a very sophisticated job. There are two facts that (2) Ecological Renovation process make this work special and difficult. Based on the performance information obtained in (1) Building envelopes cannot be changed easily due the field investigation, renovation goals and strategies to the rules 15 for cultural and architectural value Figure 5. Contents and methods of ecological renovation design. 258 J. WU ET AL. preservation in China. Possibilities of interior spa- Zhong-nong-li block, although having great cultural & tial change must also be considered based on the architectural value, were in poor physical condition. realities of the existing space layout, structural Lack of maintenance, poor or no thermal insulation, system and piping layout from the very begin- high energy consumption and poor interior environ- ning. Therefore, ecological methods and technol- ments are the major problems in these buildings. ogies that can be used effectively for new Most of the residents couldn’tafford heating and/or buildings might not be suitable for old buildings. air conditioning for their homes. When the exterior (2) The inhabitants are mainly elderly and people temperature was −2°C (Centigrade) in winter, the inter- with low incomes. Ecological technologies for ior temperature was only 2°C (Centigrade). Among the building performance improvement must there- residents, 63% thought it was intolerably cold in winter fore be economical in both initial construction and 62% thought it was intolerably hot in summer. The and future maintenance phases. gap between measured interior average temperature and people’s thermal comfort range is 17.5°C (Centigrade)! We can imagine how uncomfortable the interior living environments could be. (Figures 7 and 8) 3.1. Field investigation and measurement Second, most of the buildings were constructed without insulation and damp-proofing treatments. To some extent, the problems the selected buildings Over time, the walls get very wet and seriously mil- face are very typical for all housing stock built between dewed. According to the field investigation, almost 1840 and 1949 in China. (Wu and Dong 2013) half (48%) of the walls and furniture get seriously The special situation for most housings in China is that mildewed in summer and almost 1/3 (31%) got ser- cooling and heating are available only in some buildings iously mildewed in winter. in the hottest and coldest months, while all the other In this case, it is almost impossible to further housings—and in other seasons—mainly depend on improve building performance of these buildings by natural day lighting and ventilation. This is especially simple renovation (painting, façade renovation, etc.). true in the housings in Zhong-nong-li. According to our We need more thorough ecological renovation to get field investigation, more than 39% of the occupants are real improvement in building performance and levels low-income retired elders (more than 60 years old), with of comfort. living area per household only 41–60 square meters (42%). Fewer than 1/3 of the dwelling units have air conditioning (mechanical heating and cooling) and 3.3. Ecological renovation process in two steps among them only 1/2 (48%) would use air conditioning when it is intolerably cold or hot. (Figure 6). With consideration of economic factors, ecological renovation in this paper follows two steps: basic reno- vation for short-term improvement and thorough 3.2. Building performance evaluation renovation for the long run. Field investigation in both the hottest summer and Basic renovation provides the most economical way for immediate improvement in living environments. It is coldest winter proved that most of the housing in the Figure 6. (Upper): Situation of households using air conditioning in Zhong-nong-li housing in Nanjing, China. JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 259 Figure 7. (Middle): Temperature of interior space of Zhong-nong-li housing. Figure 8. (Lower): Quantitative comparison of the gap between measured interior temperature in Zhong-nong-li housing in winter and the thermal comfort range. applied to housing with high cultural value but in poor before and after renovation were shown. We can see that condition, and with few opportunities for thorough improvement in building performance is significant. renovation in the near future. The contents of basic renovation include building repairs (especially roofs), 3.3.1. Basic renovation for short-term improvement shadings and the installation of energy-efficient doors In basic renovation of the Zhong-nong-li project, and windows if possible. On the other hand, thorough much attention was paid to shading of openings renovation, although costing much more, could insure (Figure 9). According to our previous research, shad- comfortable interior environments in the long run, espe- ing is among the most economical and efficient cially for those units converted into other functions. ways to improve building thermal performance in Numerical animation and analysis software such as the hottest season. Shading is widely used in build- ECOTECTand CFD wereusedtomakequantitativesimu- ings in China and other countries. In the Chinese lation of the real effects of ecological renovation, national green building code, it is required that enabling easy evaluation and further improvement. “Shadings should be used on buildings when Changes in the status of natural lighting and ventilation needed.” 260 J. WU ET AL. Figure 9. Basic renovation: shading design of housings in Zhong-nong-li. Comparison of facades before and after shading design. It can be seen that installing shading elements is (1) Shading design in the Zhong-nong-li project a simple and effective way to improve the building performance of buildings in China. If combined with A key point of shading design is that it should not other performance improvement methods (such as only follow the form of the original façade, but is also updating doors & windows, adding wall insulation, make sure the shadings could prevent excessive direct etc.), it will play a greater role in the improvement of radiation from entering buildings in summer while indoor thermal environment. allowing as much sunshine as possible in winter. In the Zhong-nong-li housing, shading devices were designed according to the original facade. Horizontal 3.3.2. Thorough renovation for the long run louvers were designed on the south façades to keep In thorough renovation, attention was paid to out the direct radiation at noon at higher solar altitude interior spatial adjustments and function improve- while vertical shadings were used on the east and west ment. The target buildings were originally row facades to provide shelter from morning and after- houses. After decades of changes in occupants noon direct radiation at much lower solar altitudes. and ownership units, the current situation is not The form and size of shadings were decided by good, lacking kitchen, toilet and other sanitation calculation. facilities. Living space per family is very small, most Mostly painted in chestnut color or brown, wood is of them without kitchen and toilet. The indoor widely used in housing stock built between 1840 and natural day lighting and ventilation conditions are 1949. Therefore, in ecological renovation the materials also very poor. we chose for new shadings were mainly wood and Space performance was improved by space adjust- bamboo commonly found south of the Yangtze River. ment and function improvement as follows. Through waterproof and anticorrosive treatment, wood and bamboo in clear water-based paint worked (1) Thorough renovation for housings still used well with red bricks of the old buildings. (Figure 9) as housings (2) Evaluation of the performance of shading In thorough renovation for the housings that will still be used as housings, the original reinforced Numerical animation showed that application of concrete beam and slab structure was retained. shading devices could reduce interior temperatures Structural integrity for earthquake design was stu- by 3–5°C (Centigrade). If further upgrading of windows died before some of the non-load-bearing walls were done at the same time, in total the interior tem- were removed. perature could be reduced by 4–6°C (Centigrade). JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 261 (a) Functional improvement ventilation, some partition walls were removed in order to improve the living conditions as well as Kitchens and toilets were added to solve the natural day lighting and ventilation situations. problem of lack in service facilities. The middle parts between the north side and south side of (c) Simulation and Quantitative Evaluation housings were used for new toilets (the blue parts in plan) for every households, and the space on the Through the simulation of ECOTECT, we found north side of the first floor were used as kitchen that through the adjustment of space layout, the and dining rooms. improvement in natural day lighting and ventila- tion in interior space was obvious. Further design (b) Space adjustment was made by adding skylights to improve natural lighting situations in the middle part of the build- On the basis of adding kitchen and bathroom facil- ing. According to the analysis of CFD, the situation ities, we adjusted the layout of the floor plan by remov- of ventilation in the room was greatly also ing some walls inside the building. For rooms too small improved, especially the wind speed in rooms or too poor in terms of natural day lighting and (Figure 10). Figure 10. Thorough renovation for buildings still used as housings: Design and simulation before and after renovation. (Upper plans) Plan before and after renovation (Middle figures): Simulation of natural day lighting before and after plan adjustment (Lower figures): Simulation of natural ventilation before and after renovation 262 J. WU ET AL. (2) Further functional changes and space re- facade must be retained. Therefore, internal thermal organization for housings that will be chan- insulation was adopted, and the upgrading design of ged into other functions doors and windows should also follow the original forms of the façade. Structural reinforcement is necessary for further func- In accordance with the principle of cost from less to tional or layout changes. After the structure is rein- more, technology from simple to complex, several steps forced, the interior space will have greater freedom for of combining technical methods were tested: shadings, space reorganization. For the housings in Zhong-nong- shadings + doors & windows upgrading (double-layer li, the space re-organization design were made also on glass), shadings + doors & windows upgrading + 50mm the premise of protecting the original facades. Service EPS insulation board, and shadings + doors & windows spaces were gathered together in the north part so all upgrading + 100mm EPS insulation board. Energy Plus the other spaces could accommodate future changes in was used for simulation and analysis of building energy space layout and occupant requirements (Figure 11). consumption and thermal performance of each step to show the effect of each step. The following conclusions (3) Building envelope upgrading were got through quantitative simulation and analysis. According to the rules for renovation of housing (a) Shading could greatly reduce the annual energy stock between 1840 and 1949 in China, the original consumption of cooling in summer but has little Figure 11. Plans before and after renovation for housings converted into other functions. (Upper and middle planes): Plans for housings converted into Café (Lower plans): Plans for housing converted into shops. JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 263 effect on the energy consumption of heating in Acknowledgments winter. So shading elements have a great effect The financial support from the Research Program of National on reducing the energy consumption of the Natural Science Foundation of China (51678123, 51208089) is whole year. acknowledged. (b) Beside shading, the change of single-layer to double-layer glass windows could greatly affect the further reduction of heating energy con- Disclosure statement sumption in winter but has less effect on the No potential conflict of interest was reported by the authors. cooling energy consumption in summer. So shadings + doors & windows upgrading have a greater effect on reducing the energy con- Funding sumption of the whole year. (c) Compared with the above-mentioned meth- The financial support from the Research Program of National ods, adding insulation to exterior walls (for Natural Science Foundation of China (51678123, 51208089) is acknowledged. this project, internal insulation was chosen as already explained) could greatly reduce the energy consumption during the whole year. References EPS insulation boards were attached to the Autodesk. “Autodesk ecotect analysis.” Accessed April 2014. inside of exterior walls, With the addition of http://www.autodesk.com.cn/adsk/servlet/pc/index?id= 50 mm EPS insulation layer, the annual total 15183807&siteID=1170359 energy consumption was reduced by 75%, Feng, C. H., and H. Lu. 2003. “Research on Value and Reuse of while with a 100mm EPS insulation layer, the Nanjing Minguo Buildings.” Nanjing Social Sciences 12: annual total energy consumption was reduced 102–107. by 84%. 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