Thermal comfort and the Mahoney tables in Shanghai building bioclimatic designBo Xia Thermal comfort and the Mahoney tables in Shanghai building bioclimatic design 1 1 Bo Xia College of Architecture, Chang’An University, China,
[email protected] Abstract In order to research the Shanghai building bioclimatic design strategy, the paper studies the Shanghai building with the method of Mahoney tables that are a set of reference tables used in architecture as a guide to climate-appropriate design combined with Shanghai meteorological data, and puts forward a series of building bioclimatic design strategies for Shanghai climate characteristics. Finally, according to the climatic characteristics of Shanghai and the residents’ living characteristics, the limitations of strategies proposed by the Mahoney tables were analyzed. Keywords: Mahoney Tables; Shanghai; Bioclimatic Design 1. Introduction The Department of Development and Tropical Studies of the Architectural Association in London developed a methodology for building design in accordance to climate [1]. The proposed methodology is based on three stages of design, the sketch design stage, the plan development stage and the element design stage [2]. For the purpose of systematic analysis during the three stages, they introduced the Mahoney Tables, which research on the thermal comfort using the standard effective temperature (SET). The tables are used to analyze the climate characteristics, from which design indicators are obtained. From these indicators a preliminary picture of the layout, orientation, shape and structure of the climatic responsive design can be obtained. Shanghai sits on the Yangtze River Delta on China's eastern coast. The municipality as a whole consists of a peninsula between the Yangtze and Hangzhou Bay, mainland China's second-largest island Chongming, and a number of smaller islands. It is bordered on the north and west by Jiangsu Province, on the south by Zhejiang Province, and on the east by the East China Sea. The city proper is bisected by the Huangpu River, a tributary of the Yangtze(shown in Fig.1). The vast majority of Shanghai's 6,340.5 km2 land area is flat, apart from a few hills in the southwest corner, with an average elevation of 4 m. The city has many rivers, canals, streams and lakes and is known for its rich water resources as part of the Taihu drainage area. Fig. 1 Geography of Shanghai Advances in information Sciences and Service Sciences(AISS) Volume5, Number9, May 2013 doi:10.4156/AISS.vol5.issue9.4 27 2 °C in the coldest month January and 27. and cold northwesterly winds from Siberia can cause nighttime temperatures to drop below freezing.9 °C in the hottest month July.Thermal comfort and the Mahoney tables in Shanghai building bioclimatic design Bo Xia In order to research the relationship between the Shanghai climate and building energy efficiency design and determine the most appropriate building energy efficiency design strategies in Shanghai. Fig. for an annual mean of 16.878 hours of sunshine and 132 rain days per year.2 Shanghai Day dry bulb temperature statistics 2. The city is also susceptible to typhoons in summer and the beginning of autumn. 13. Mean relative humidity and Humidity group Mean relative humidity Humidity group Below 30% 30-50% 50-70% Above 70% 1 2 3 4 28 . Table 1.1 Shanghai's Climate Overview Shanghai has a humid subtropical climate and experiences four distinct seasons. Winters are chilly and damp. occasional downpours or freak thunderstorms can be expected.1% in summer.2).7 days exceeding 35 °C annually. the paper completed the analysis of the Shanghai outdoor climatic conditions described in Table 1-2.0% in winter. The rain intensity is more moderate rain and drizzle. and about 70% of the rainfall is concentrated in the AprilSeptember. Summers are hot and humid. 2 Climatic data 2. monthly mean range.1 °C (shown in Fig. although most years there are only one or two days of snowfall. monthly mean maximum temperature. with an average of 8. Shanghai experiences on average 1. The seasonal distribution of rainfall is more uniform in Shanghai and it accounts for about 40. the paper adopts the Mahoney tables to Shanghai analyzing the design strategies according to the Shanghai meteorological data [3] [4]. Using the meteorological data provided by the Shanghai Municipal Meteorological Observatory. relative humidity and precipitation.2 Shanghai's Climate data The Mahoney tables analyze the meteorological parameters including the monthly mean minimum temperature. The city averages 4. 7 19.5 27.7 Oct .5 6. g. The classification is established as follows: Above comfort limit H Within comfort limit N Below comfort limit C The humidity and comfort classifications are compared for each month to establish humidity and arid indicators. HG: humidity group.2 22.0 11.7 25. Table3. 15 ~ 20℃ and <15℃.Thermal comfort and the Mahoney tables in Shanghai building bioclimatic design Bo Xia Monthly mean max.3 7.1 5.7 5. . * 29. according to the annual mean ranges given in Table 3 respectively (i.3 24. Ma r. †Lowest monthly mean.1 7 76 4 71 4 78 4 75 44 118 30. Table 2.4 17.1.7 13.e. Shanghai climatic data Apr Ma Jun Au Sep Jul.9 15.6† 3. Feb .7 73 4 76 4 82 4 81 4 82 4 76 4 73 4 67 3 66 3 63 85 212 142 230 76 64 43 34 Tota l 1186 * Highest monthly mean.. which is shown in Table 3. Comfort limits AMT over 20℃ AMT 15-20℃ AMT under 15℃ Day Night Day Night Day Night 1 26-34 27-34 23-32 14-23 21-30 12-21 30-50% 2 25-31 17-24 22-30 14-22 20-27 12-20 50-70% 3 23-29 17-23 21-28 14-21 19-26 12-19 >70% 4 22-27 17-21 20-25 14-20 18-24 12-18 Average RH HG 0-30% RH: relative humidity.9 10. RH: relative humidity. AMR=Annual mean range=Highest .9. 7. HG: humidity group 3 The Comfort limits The Mahoney tables take into account the climatic adaptability of people in different climatic zones in determining the thermal comfort limits. and divide the comfort zone into three temperature ranges in accordance with the level of the annual mean temperature (AMT): ≥ 20℃.0 24. AMT: annual mean temperature. AMT=Annual mean temperature= (Highest + Lowest)/2=29.8 27.5 6.6 21. maxima with the day comfort limit and minima with the night comfort limits).4 5. Furthermore the Mahoney tables take into account people difference dressing habits and activities in the day and night. 29 .1 6 7.6 12 17. y . Dec .3 6.4 6.0 21.7 9.7 6.2 5. Nov . and limit difference thermal comfort range on the day and night the two time periods.5 4. (℃) Monthly mean range (℃) RH HG Rainfall (mm) Jan . 4 The analysis of each month comfort limit Similarly the monthly mean maxima and minima of the site in question are compared to the day and night comfort limits for each individual month. (℃) Monthly mean min. .Lowest=16.4 1. 0 24. Nov . A3 Indicates winter or cold-season problem.9 15. (℃) Night comfort min. H: above comfort limit. Jun. Diagnosis of Shanghai climatic data Mar Apr Ma Aug Feb. Sep. night=N.7 9. Problems may arise with even low precipitation. It may be needed also when nights are comfortable outdoors but hot indoors as a result of heavy thermal storage (day=H. It applies when temperature within the comfort limit (day thermal stress=N) are combined with high humidity (HG=4).1 Humidity indicators H1 Indicates that air movement is essential. (℃) Day comfort min. but will be inevitable when rainfall exceeds 200mm per month. HG=1or2) and when the diurnal range is above 10℃. A2 Indicates the desirability of outdoor sleeping space.0 25 25 25 25 25 25 25 25 25 25 28 28 20 20 20 20 20 20 20 20 20 20 21 21 1. 30 . The climatic data of Shanghai is tabulated in Mahoney’s Tables4-5. These occur when day thermal stress=C.4 17.1 6 7. Diurnal mean range (℃) HG Monthly mean max.0 11. (℃) Night comfort Max.6 12 17.3 20 20 20 20 20 20 20 20 20 20 21 21 14 14 14 14 14 14 14 14 14 14 14 14 C C C C N H H H H N C C C C C C N H H H H N C C HG: humidity group. It applies when high temperature (day thermal stress=H) is combined with high humidity (HG=4) or when the high temperature (day thermal stress=H) is combined with moderate humidity (HG=2 or 3) and a small diurnal range (＜10℃).6 3. H3 indicates that precautions against rain penetration are needed.7 5.9 10. Dec. (℃) Day comfort Max.6 21. This applies when a large diurnal range (10℃ or more) coincides with moderate or low humidity (HG=1.1 5.7 6.3 24.7 4 4 4 4 4 4 4 4 4 4 3 3 7.2or3). N: within comfort limit.3 6. H2 Indicates that air movement is desirable.5 4.8 27. It is needed when the night temperature is high (night thermal stress=H) and the humidity is low (HG=1 or2). 4.7 13.5 6.2 22. (℃) Monthly mean min.4 30. . C: below comfort limit.7 25.2 Arid indicators A1 Need for thermal storage. y . Jul.4 5.7 19.7 29.5 27. Oct. (℃) Thermal stress: Day Thermal stress: Night Table 4. 6. Jan. .Thermal comfort and the Mahoney tables in Shanghai building bioclimatic design Bo Xia 4.2 5.1 7 7.5 6.4 21. y . Indicator total from Table(5) Humid Arid H1 4 H2 2 H3 2 A1 0 Table 6.20-40% ★ 3-12 0 ★ 31 .10-20% 11 Medium openings. The relation between the climatic data of Shanghai and recommendations design strategies is tabulated in Mahoney’s Tables 6. No v. Tot al Humid H1 Air movement H2 Air movement H3 Rain protection Arid A1 Thermal storage A2 Outdoor sleeping A3 Coldseason X X X X X 4 X X 2 X 2 0 0 X X X X X X 6 5 Application of Mahoney tables in Shanghai The Mahoney tables established a relationship between climate indicators and building design. Feb . Ap r. Sep t.12 11.1 Any other conditions 0-2 3-12 Building oriented on east to west axis to reduce exposure to sun Compact courtyard planning ★ ★ 0-5 6-12 1. Indicators Ma Jun Au Jul. g.2 1 2 Spacing 3 Open spacing for breeze penetration 4 As3. short time lag 13 Heavy external and internal walls 2-12 0.12 0. but protect from cold/hot wind 5 Compact planning Air movement Rooms single banked. Design recommendations Recommendations A2 0 A3 6 Layout 0-10 5-12 0-4 11.1 0. Dec .1 ★ Walls 12 Light walls. And the recommendations of the climatic analysis for Shanghai building design are summarized in Table7. Permanent 6 provision for air movement Double banked rooms with temporary 7 provision for air movement[ 8 No air movement required Openings Large openings. Table 5. 40-80% of N and S 9 walls 10 Very small openings. Ma r.Thermal comfort and the Mahoney tables in Shanghai building bioclimatic design Bo Xia Jan .12 2-10 0. Oct .1 0 11. Through the above analysis.7% (shown in Table 3). the Shanghai climatic require building not only has a certain passive cooling strategy [5].7% of the time when building do not need energy to heating or cooling. Building requires either mechanical air conditioning or other passive cooling or heating strategy to meet the building interior environment comfortable. The ratio of above comfort limit is 33. also require 32 . the ratio of below comfort limit is 50% there are below comfort limit conditions from November to April (shown in Fig.3 The condition of Shanghai year-round comfort limit 2. short time lag Light insulated roofs 6 Conclusions 1.3). and both day and night are above comfort limit from June to September. The Shanghai climatic (including day and night) within comfort limit is only about 16. over 8 hours’ time lag Outdoor sleeping 16 Space for outdoor sleeping required Rain protection 17 Protection from heavy rain needed (★ in the table is appropriate building design strategies for Shanghai) Table 7. and the natural environment can meet the comfortable building internal environment. but protect from cold/hot wind Rooms single banked. Permanent provision for air movement Medium openings. The other time of the Shanghai climatic is out of comfort limit and can't meet the building interior environment comfortable requirement. Recommendations for building design in Shanghai Element Layout Spacing Air movement Openings Walls and doors Roofs Recommendations Building oriented on east to west axis to reduce exposure to sun Open spacing for breeze penetration. that is Shanghai throughout the year only 16. it can be found that the Shanghai natural environment is not very ideal. Through the above analysis.Thermal comfort and the Mahoney tables in Shanghai building bioclimatic design Bo Xia ★ 0-5 6-12 2-12 3-12 Roofs 14 Light insulated roofs 15 Heavy roofs. Fig.3%. such as rooms single banked.20-40% Light walls. light walls and so on. Stefan Behling. Yin Qing. Yujuan Liu. but the essence of building is to offer people a comfortable indoor environment. Advanced Institute of Convergence Information Technology. Prestel. [7] Ling Tan. [6] Xibiao Cai. [11] Zhang Jun. 2011. 2011. Edwin N. pp. However. Shanghai residents have a better tolerance to cold environment.327-336.Mcintyre. but also have a greater tolerance in the winter cold environment than people living in the tropics. pp. A Division of International Thomson Publishing Inc. Pitman Publishing Ltd. Hamid Marafia. A. 4. No. Vol. References [1] Ali Sayigh. 2012. USA. such as open spacing but protect from cold/hot wind design strategy[8] indicated by Mahoney Tables (shown in table6). Tongji University Publications Limited. 22.7. Advanced Institute of Convergence Information Technology. no. International Journal of Advancements in Computing Technology.1.11-23.USA. Climate and Energy”.6. pp. [10] Baruch Givoni. the Mahoney tables have some limitations. “Building. vol. China. 8. In Proceeding of 2nd International Conference on Civil Engineering. vol. 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Renewable and sustainable Energy Reviews. 1998. International Journal of Advances in Information Sciences and Service Sciences.18. No. 2012. 1980 [4] T. and Shanghai residents live for so long time in such climate that they not only have a certain degree of adaptation and tolerance of summer heat [10]. 3. pp. “Comfort. pp. 4.A.” Indoor Climate”.3. Dongyu Wang. 2000. Therefore there may be some errors for the evaluation of the Shanghai winter environment that the actual below comfort limit situation should be less than 50% [11]. no. 14.31963201. The Mahoney tables is mainly aimed at tropical climate. " Ecological Architecture “Passive Control” Theory and Technical System ". “Energy-efficient Cooperative Broadcast Transmission in Clustered Wireless Sensor Networks”. Acknowledgments This work was financially supported by the Special Fund for Basic Scientific Research of Central Colleges.337-346. USA. [9] Bo Xia. International Journal of Advances in Information Sciences and Service Sciences. “Energy-Efficient Wireless Sensor Networks: A Novel Dynamic Clustered and Cross-Layer Cooperation Approach”. Xiaoxiang Wang. Applied Science. “Climate-Responsive Building”.Thermal comfort and the Mahoney tables in Shanghai building bioclimatic design Bo Xia passive heating strategy [6] [7]. USA.. 2012. “Climate Consideration in Building and Urban Design”. [12] Bo Xia. Huiqiang Tang. climate analysis and building design guidelines”. [8] Sophia Behling. so it is also important to pay attention to the passive heating strategy used in Shanghai building energy efficiency design [12].