可持续学校：通风优于传统的学校（中英文对照）.doc

大学毕业设计 文 献 翻 译源文献: 2009, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (). Published in ASHRAE Transactions 2009, vol. 115, part 2. Inc. (). Published in ASHRAE Transactions 2009, vol. 115, part 2 姓 名：指导教师：专 业：建筑学大学建筑工程学院2012年5月外籍文献：Ventilation of Sustainable Schools:Better than Traditional Schools?W. Zeiler G. BoxemSUMMARYDuring the last decades in the United Kingdom several educational buildings were built with a strong environmental ethos, real icons of a new generation of low-energy sustainable buildings. In some of the buildings post occupancy evaluations were held and buildings performance was revealed. Also in the Netherlands during the last years several new concepts were developed for sustainable schools. This is an interesting topic as many of those schools had problems concerning energy efficiency, indoor air quality and thermal comfort. In the case of sustainable schools much effort went into the design process of the schools to try to find better solutions to face the problems of the traditional designs. This resulted in different solution concepts, which raises the question which are better school concepts. From literature three evaluations from the UK and one overview of 5 sustainable educational buildings from the Netherlands are given, which show that sustainable educational buildings are not always without flaws. In the paper two of the first Dutch sustainable elementary schools are compared with 9 more traditional schools of the Netherlands to conclude whether the sustainable schools perform better than traditional schools.INTRODUCTIONPresently sustainability becomes a necessity as effects of Global warming become more clearly. It is important to start early with the educational aspects of the necessary change in behavior and thinking, sustainable schools could play an important role. The whole concept of a sustainable school building is based on principles of sustainable development which deal with the limited availability of natural resources, the interdependence with nature, the fundamentals aspects of interdependence with nature, the fundamentals aspects of production and consumption, and the issue of equity within, between and among generations 1.As the icon of a new generation of sustainable educational buildings which was completed in late 1993, the Queens Building at De Montfort University, Leicester, gained a reputation with its startling architecture, in particular the distinctive ventilation chimneys 2, see Figure 1. The Queens Building was seen as the first in a new generation of lowenergy, naturally ventilated sustainable buildings. Architect Short Ford Associates worked on the building design alongside environmental engineer Max Fordham LLP, Cambridge rchitectural Research (on the stack-effect chimneys) and Bristol University (on the physics of the airflow). The 10,000 m2 building is L-shaped containing a complex arrangement of laboratories, classrooms and offices. The structure is almost exclusively naturally ventilated 2.A detailed picture of the buildings performance was revealed in 1996, when a post-occupancy evaluation was carried out as part of the PROBE (Post-occupancy Review of Buildings and their Engineering) project. The assessment revealed a number of key shortcomings. Unresolved defects meant that for the first two years the building operated with problems in critical mechanical and control systems 2. PROBE researchers found that the buildings design seemed to be effective at maintaining a comfortable environment,although the survey of its occupants, conducted by Building Use Studies (BUS), showed dissatisfaction with high summertime temperatures and stuffiness in both winter and summer months 2.A revisit during early August 2006 revealed that some parts of the building have changed dramatically since the PROBE assessment, while others are much as they were when it took place. During the revisit an occupant survey was held and forty-five questionnaires were completed (compared with 75 in 1996). In general terms, satisfaction with temperatures in both summer and winter is the same, although occupants perceive the air in winter to be better. Levels of satisfaction are very dependent on location. For example, the relatively high satisfaction rate for the refurbished offices is not matched by users in the new laboratories. In 1995, Hampshire County Council Architect Sir Colin Stansfield-Smith designed a imaginative, low energy educational building for Portsmouth University employing several environmental systems and ventilation strategies designed to liver comfortable conditions and be of didactic value to the students. Externally, the building is a white-painted rendered fortress 3, see Figure 2. Internally, it is light and bright, with white painted walls, windows and steelwork, complete with simple but good finishes. Five stair towers around the buildings periphery act as natural ventilation air exhaust paths for the classrooms, studios and staff offices (with the exception of those on the top floor). The Portland Building was also investigated by the PROBE Team 3.Questionnaires by 46 staff rated the building well as an all-rounder, coming just within the top 20% of the reference dataset, though people were happier with the aesthetics than with comfort or functionality 3. There was however a good overall wintertime comfort, even though the building was judged to be hotter, stiller and stuffier than average. Summer comfort was judged average overall, but with a wide range of response and some people stated that is was significantly hot. The building has good perceived air quality, in both winter and summer, besides some local problems 3. During the summer of 1997 an analysis of monitored air and slab temperatures was done by Kolokotroni et al. for the purpose of designing naturally ventilated educational building. From their analysis, they concluded that natural ventilation coupled with exposed thermal mass can reduce the effect of external hot weather and establish comfortable conditions within the building. It has also shown that if this moderating effect of thermal mass and natural ventilation is not controlled, unfavourable internal conditions can be established under certain external weather; in particular, cold spells during the summer 4. Since occupation the major changes have been a general increase in the use of computers, leading to occupancy and equipment densities and heat gain and ventilation requirements beyond design expectations in some rooms. Lack of flexibility to cope with increased capacity is a weak point of the sustainable design concept.In the study of Sharples et al. 2007, Norfolk Community Primary School in Sheffield, UK, see Figure 3, built in 2005 with many sustainable features, was subjected to a post occupancy evaluation (POE) that involved both a social analysis and environmental monitoring. One of the key questions of the study was: did the school performing better environmentally than a standard school 5?The UK Governments Department for Education and Skills (DfES) Building Bulletin BB101 Ventilation of School Buildings recommends that for teaching and learning spaces between the start and finish of teaching on any day the average concentration of carbon dioxide should not exceed 1500 parts per million (ppm). In addition, BB101 recommends that for any occupied time, including teaching, the occupants should be able to lower the concentration of carbon dioxide to 1000 ppm. Figure 4 shows the mean CO2 levels for the teaching and week-end periods, the dashed lines show the 1500 ppm and 1000 ppm levels suggested in BB101.Figure 5 presents the indoor and outdoor air temperatures over a ten day winter period from Friday 17 February to Monday 27 February 2006. The dashed line in Figure 5 is the internal air temperature of 18.0C recommended in the School Premises Regulations and quoted in Building Bulletin 87 5.As can be seen from these three British examples sustainable buildings are not flawless. So what is the situation in the Netherlands? Unfortunately there were only a few case studies done. Most important one was the evaluation of the first pilot projects of sustainable educational buildings. To show what is possible in practice with sustainable building design, the Dutch government sudsidized several pilot projects, from the 17 utility buildings there were 5 educational buildings: Van Hall Institute, Hogeschool Limburg, Educatorium, Peuterpalet and Scholencomplex Rijkerswoerd. The performance of these schools were monitored during a couple of years and presented in a overall study 6. The results are given in Figure 6. If we realize that normally the percentage of dissatisfied is between 10 to 20% we see clearly that some of the sustainable schools perform on some aspects worst than traditional schools.In the Netherlands with respect to sustainable educational building the main focus has been on energy saving, leading to a reduction of 30% compared to the Dutch building regulations. This led to the application of hybrid ventilation: natural supply and mechanical exhaust ventilation. Within the Annex 35 Hybrid Ventilation in New and Retrofitted Buildings, an international research project initiated by the IEA Implementing Agreement Energy Conservation in Buildings and Community Systems, the scope was to obtain better knowledge of the use of hybrid ventilation technologies 7. To avoid cross ventilation, each classroom has been equipped with a local ventilation system, that consists of 2 electronically controlled inlet grills in the facade and a fan supported natural exhaust chimney. CO2 sensors and temperature sensors automatically control the ventilation system. To meet the energy performance requirements the building has a high level of thermal insulation (U-values, the overall heat transfer coefficient, of opaque parts 0.31 W/m2/K = 1,76 Btu/ft F h, U-value of windows 1.8 W/m2/K = 10,21 Btu/ft F h), good air tightness and energy efficient building services (high efficiency natural gas-boiler for heating and domestic hot water and high frequency lighting). The extra 30% energy savings above the mandatory level of the building regulations are provided by the hybrid ventilation system (15%) and daylight sensors and a central sweep switch on the lighting system (15%).METHODOLOGYTwo sustainable designed schools were analyzed and the results compared with other more traditional schools. To investigate the results of the sustainable schools measurements were done concerning thermal comfort and indoor air quality. During a week different measurements in schools were undertaken to be able to define the quality of indoor air quality and thermal comfort. Of the two sustainable schools, one school is the first sustainable elementary school of the Netherlands 1, the other school was part of the IEA (Inter-national Energy Agency) Annex 35 Hybrid ventilation project 7, so they are both relevant examples of sustainable designed schools as such.Indoor Air Quality (IAQ) at schools is of special concern since children are extremely sensitive to results of poor air quality. IAQ in schools must reach the basic requirements and should be considered as a high priority because 8: (1) Children more sensitive as they still developing physically and more likely to suffer from indoor pollutants, these growth processes are delicate and vulnerable to disruption, (2) Children are less well able than adults to metabolise and excrete most environmental toxins, (3) Children are relatively more heavily exposed to environmental toxins as they breathe higher volumes of air relative to their body weights. Good air quality in classrooms supports childrens learning ability. Poor IAQ in schools influences the performance and attendance of students, primarily through health effects from indoor pollutants 9. Literature on relationships 10 between indoor air and environmental quality (IEQ) in class rooms and students health and academic performance has been reviewed 11. Carbon dioxide concentrations are often used as a substitute of the rate of outside supply air per occupant 12. IAQ in schools is primarily evaluated by CO2-concentrations. ASHRAE Standard 62-1999 recommends an indoor CO2-concentration of less than 700 ppm above the outdoor concentration (1200 ppm) to satisfy comfort criteria with respect to human bio ffluents. Dutch schools have to meet the Dutch Building Code (Bouwbesluit), which recommends a level of 1000 ppm CO2-concentration with a maximum of 1200 ppm.SchoolsBetween January 29th till March 31st 2004 measurements were conducted in 5 selected schools. The measurements were conducted in alphabetical order from school A1 to E1, see Table 1 13.Between January 13th till February 22st 2005 the second series of long-term measurements were conducted in 6 new selected schools, see Table 2. Schools B2 and F2 are the sustainable designs 14.MeasurementsOne classroom in each school building was selected for the measurements in the heating season during 1 week which include long-term measurements of air temperature, radiant temperature, relative humidity and air velocity. Equipment specifications used for those long-term measurements are shown in Table 3.QuestionnairesIn all schools, questionnaires were given to the teachers to get an impression of the satisfaction of the users, with regard to indoor air quality and thermal comfort. The questionnaires had questions about environmental perception and application of the system for the winter situation comprised: perceived thermal comfort, perception of indoor air quality etc.13The users have been asked to rate different aspects of the comfort. Distinction is made between summer and winter. Users opinion is the central point of this research. The questionnaire used is based on the validated list which has been developed in the Health Optimisation Protocol for Energy fficient Buildings research 15. The questions are based on a unipolar scale and should be interpreted as: 1 = very good 5 = unacceptable. Table 4 gives the complete overview of the completed questionnaires from the different schools. As the research was focused on primary schools we were not able to ask the pupils questions and could only let the teachers fill in the questionnaires.RESULTSResults Measurements t is important to look at the CO2-concentrations as a indicator for the indoor quality within the classrooms. The average level was determined for which during 50% of the time of use his level would not be succeeded, CO2-PM50, also the level was determined for which 95% of the time of use this would not be succeeded, CO2 PM95. These values are based on the actual measurements and the actual occupations of the classrooms. Also the CO2-concentrations were calculated based on the measurements and the additional increase of the CO2 ncentrations based on the design conditions of an occupation of 32 pupils and one teacher in the classroom, the so called CO2-PM 95 33p* value, see Table 5. Because of it significant the CO2-PM 95 33p* value is presented in Figure 7 separately. Also the effective ventilation rate within the classroom is determined by using the rise of CO2-concentrations. Results QuestionnairesThe focus of this paper is on the IAQ. So the focus was on these aspects and the teachers were asked how they perceived the humidity of the air, the freshness, odors and overall satisfaction about the Indoor Air Quality, see Figures 8, 9, 10 and 11. Comparison ResultsThe following table represents the results of the measurements and questionnaires. For the important aspects the comparison is made between the average of the “traditional” school of series 1 and 2 compared to the specific sustainable design for school B2 and F2, see Table 6. To sum up all the results overviews are presented of all the calculated mean PM 95 33 CO2 concentration based on the measurements during the winter period of all the projects and the results of questionnaires about aspects of perceived IAQ in winter situation.As can be seen the sustainable schools do not perform better on all aspects. Remarkable is the difference in quality of IAQ perceived by the teachers of school B2 and measured through the PM 95 33 CO2. Although the measured improvement is more than 20% related to the CO2 concentration the perceived overall satisfaction in school B2 is worst by 21%. In school F2 the perceived overall IAQ satisfaction is in line with the expectation based on the improved CO2 concentration withan 29% better results compared to the average of traditional schools.The perceived feeling of humidity by the teachers of thesustainable schools B2 and F2 is worst compared to traditionalschools. This can be explained as the ventilation is controlledby CO2 and therefore related to the hours of use, besides these hours ventilation is kept on a much lower level. This lower ventilation rate is probably not sufficient enough to dispose all moisture within the classroom after the pupils have left the classroom. Also the aspect perceived of odor indicates that the overall ventilation is not enough to dispose of the odor of the pupils after the lessons and maybe also odor of emitting building materials in the classroom with as result that odor is left within the classroom.DISCUSSIONIn the past in the Netherlands different investigations on indoor air quality were conducted and CO2 levels measured. In 1992 the local health department (GGD) in West-Brabant researched indoor air quality in secondary education buildings. Measurements of CO2 levels were done and levels up to 4800 ppm were detected 16. In 1997 IAQ measure