Investigating potential of natural driving forces for ventilation in four major cities in China

The potential of natural driving forces for ventilation in buildings is the possibility for providing sufficient outdoor air by only natural ventilation. Based on the early work of Fracastoro et al. (Fourth international conference on indoor air quality, ventilation and energy conservation in buildings—IAQVEC, vol. III, Hong Kong: The City University of Hong Kong; 2001. p. 1421–9.), we develop a simple prediction model for this natural ventilation potential applicable to Chinese residential buildings, using a simple analytical model of natural ventilation considering the combined effect of wind and thermal buoyancy forces. Comparing with the existing method developed by Fracastoro et al. (2001), the present prediction does not need sophisticated multi-zone modeling calculations and the constants in the model are no longer variables. Using the weather data from International Weather for Energy Calculations (IWEC) into our simple prediction model, the natural ventilation potentials for low-rise residential buildings in four representative cities of China including Beijing in the north, Shanghai in the east, Guangzhou in the south and Urumqi in the northwest were analyzed. We introduced the concept of the pressure difference Pascal hours (PDPH) for natural ventilation, and PDPH was calculated and compared for four cities. A high PDPH value means a great potential for application of natural ventilation. In addition, hourly effective pressure differences can be obtained and analyzed statistically. This information can help the designers to determine the building opening size, or to assess whether or when mechanical ventilation is necessary. The application of the model can be a simple design tool at preliminary design stage.     

Indoor thermal environment and energy saving for urban residential buildings in China

The purpose of this survey is to investigate the actual conditions of the residential indoor thermal environment in urban areas in China for evaluating thermal comfort and predicting the energy conservation feasibility for space heating and cooling.The apartment homes under investigation were located in the urban areas of nine major cities. The questionnaire survey revealed building characteristics, the types of space heating and cooling system in use, aspects of life style, during winter and summer seasons, and so on. The measurement showed that winter indoor temperatures in Harbin, Urumqi, Beijing and Xi’an remain at a relatively stable level near 20 °C due to the central heating system installed. However in the other cities lacking central heating systems, indoor temperatures fluctuated as a function of the change of outdoor temperature. On the other hand, summer indoor evening temperatures in Shanghai, Changsha, Chongqing and Hong Kong were higher than the comfort zone of ASHRAE. Therefore it is expected that energy use for space heating and cooling in the southern China will increase in the near future because of occupants’ requirement for comfortable indoor environment. Based on the results yielded by this study, in Beijing the calculation of space heating and cooling loads indicated that the energy used to heat indoor spaces can be halved by installing thermal insulation and properly sealing the building.     

西部地域办公建筑自然通风的节能效应研究

利用Desgnbuilder模拟软件对西部地域九个城市的典型办公建筑在自然通风和非自然通风条件下进行逐时能耗模拟,以节能率和单位面积节能量为指标,结合通风潜力计算结果综合分析各地区的自然通风节能潜力。结果表明各热工分区的自然通风节能潜力大小依次为温和地区、严寒地区、寒冷地区,夏热冬冷地区总体不具备自然通风节能潜力,但是在过渡季节仍有一定的节能效果。     

不同城市自然通风建筑热舒适状况研究

通过上海、长沙自然通风建筑内进行的人体热舒适调查研究，并结合有关文献中北京和天津热舒适研究的成果，对我国目前不同城市自然通风建筑内热舒适状况进行探讨。结果认为，我国自然通风建筑内热中性温度均略高于ASHRAE推荐范围，采用实测的舒适温度作为空调温度可节约大量的能量。     

徽州传统民居室内环境及舒适度

以徽州传统民居为研究对象,通过对当地一幢典型传统民居进行为期一年的室内多项环境参数现场测试以及连续监测,从舒适性角度对民居室内环境进行研究。结果表明:徽州传统民居具有"冬冷夏凉"特性;夏季自然通风、遮阳以及隔热性能良好,其室内热环境较为适宜;冬季防寒保温及密闭性效果不佳,其室内热舒适性差;过渡季(春、秋季)室内热环境较好,人体热舒适性好。徽州传统民居室内具有较好的声环境,但是光环境不佳,大部分时段不能达到现代建筑采光设计标准。     

通风对住宅夏季空调能耗的影响

采用数值模拟方法,对一栋住宅分别位于北京、上海和广州时,不同通风量和不同通风模式下的夏季空调能耗进行了计算分析.结果表明,位于北京时,1.0h-1是最节能的通风换气次数,位于上海时,0.4h-1是最节能的通风换气次数,位于广州时,空调能耗随着换气次数的增加而线性增大,在这三个地区,间歇机械通风都有利于减少空调能耗.     

Natural ventilation potential model considering solution multiplicity, window opening percentage, air velocity and humidity in China

The paper brings about a two-opening naturally ventilated building potential model considering solution multiplicity, window opening percentage, air velocity and humidity in China. Based on previous research by Yang et al. and Luo et al., this paper developed a revised model to estimate the natural ventilation potential. There are four main improvements: Firstly, counteract of wind and thermal pressure was included and method for multiple solutions was introduced accordingly. Secondly, the model considered the natural ventilation hours for windows opening percentage. Thirdly, wind velocity and humidity were considered lastly. Fourthly, cooling and heating hours were also estimated.In case study, the paper analyzes natural ventilation potential in cities in four typical climate regions in China. Results show that there are more natural ventilation hours than previous models estimated, especially in cold climate regions.Any parameter in this model can be changed according to practical situation, such as climate data, building orientation, window size, opening position, etc. All estimated information can provide reference for architects in early stages of building design. Meanwhile, this model can be used for energy efficiency estimation and indoor environment research.     

Temperature ranges of the application of air-to-air heat recovery ventilator in supermarkets in winter, China

Energy consumption is an important issue in China. In heating, ventilation and air conditioning (HVAC) systems, more and more commercial buildings use air-to-air heat recovery ventilators as energy saving units for recovering heat from the exhaust air in ventilation systems in current years. In the present paper, critical temperatures of air-to-air heat recovery systems for supermarkets in winter are recommended and discussed for the four cities in different climate zones of China. The analysis shows that the temperature of fresh air in winter can be categorized into three regions, i.e., recovery region, transition region and impermissible recovery region. The results also indicate that the latent heat recovery is not suitable for ventilation energy savings in supermarkets in winter. Meanwhile, the applicability of sensible heat recovery in supermarkets depends on outdoor climate and fresh air flow rate. If a variable rotational speed fan is used to introduce fresh air into the building, heat recovery does always function as planned in winter for all the selected cities except Guangzhou, and most values of the COP are much higher than 2.5. Otherwise, there is the risk of negative impact on building energy savings in all cities except Harbin.     

Weather data analysis and design implications for different climatic zones in China

Measured long-term hourly and daily weather data for five cities in China, namely Harbin, Beijing, Shanghai, Kuming and Hong Kong were gathered and analysed. These cities were selected to represent the five main architectural climates—severe cold, cold, hot summer and cold winter, mild, and hot summer and warm winter. Statistical techniques and graphical methods were used to study the long-term weather characteristics of these five climatic zones. Three common climatic variables, namely temperature (dry-bulb and wet-bulb), solar radiation (global, direct and diffuse) and wind conditions (wind speed and wind direction), were investigated. The frequency of occurrence and cumulative frequency distributions were determined and presented, and implications for building and building services designs were discussed.     

高大空间热分层实测与热压通风冷却潜力

以南京某大空间建筑为对象,长45 m、宽15 m、高16 m,在9月过渡季连续多日测试了自然通风状况下的室内温度分布,发现同一垂直方向上温度的线性化程度较好,梯度在0.2℃/m左右,且随室外气象条件变化而变化。采用热压通风效应模型,计算了南京、武汉、重庆、广州4个不同夏热地区全年各月的热压通风量及满足基准通风量要求的最小上部开口面积与通风排热量。利用Energy Plus能耗软件模拟全年各月热压通风热舒适时数,发现广州地区具有最好的热压通风节能潜力。     

Field study of human thermal comfort and thermal adaptability during the summer and winter in Beijing

This study was conducted during the summer and winter in Beijing. Classrooms and offices in a university were used to conduct the survey. The respondents’ thermal sensation and thermal adaptability in both seasons were analyzed. During the study, indoor environmental parameters including air temperature, mean radiant temperature, relative humidity, and air velocity were measured. The respondents’ thermal sensation was determined by questionnaire.A relationship between indoor temperature and thermal sensation was found. In the summer study, the “scissors difference” between TSV and PMV was observed in the air-conditioned environments if the temperature was out of the neutral zone. People had higher tolerance in the hot environment than PMV predicted. During winter, the outdoor temperature had a prominent influence on thermal adaptability. The low outdoor temperature made people adapt to the cold environment. When the indoor temperature was heated to a high temperature by space heating facilities, respondents felt uncomfortable since their adaptability to the cold environment was nullified.Furthermore, the differences in thermal responses between respondents from North and South China showed that the different climates of people's native regions also affected their thermal comfort and adaptability.     

New concepts and approach for developing energy efficient buildings: Ideal specific heat for building internal thermal mass

The shortcomings or limitations of the traditional approach to developing energy efficient buildings are that they can not determine: (1) the ideal thermophysical properties of building envelope material, where “ideal” means that such material can use ambient air temperature variation and/or solar radiation efficiently to keep the indoor air temperature in the thermal comfort range with no additional space heating or cooling; (2) the best natural ventilation strategy; (3) the minimal additional energy consumption for space heating in winter or air-conditioning in summer. To overcome these problems, some new concepts for developing energy efficient buildings are put forward in this paper. They are the ideal thermophysical properties of the building envelope material, the ideal natural ventilation rate, and a minimal additional space heating or cooling energy consumption. A new approach for determining these properties is also developed. In contrast to the traditional approach (the thermophysical properties of building envelope material are known and constant so that the relating equations describing the indoor air temperature tend to be linear differential equations), the new approach solves the inverse problem (thermophysical properties, etc. of a buildings are unknown), whose solution can be a function instead of a value. As a first step, the ideal specific heat of the building envelope material for internal thermal mass is analyzed for buildings located in various cities in different climatic regions of China, such as Beijing, Shanghai, Harbin, Urumchi, Lhasa, Kunming and Guangzhou. We found that the ideal specific heat is composed of a basic value and an excessive one which is of δ function for the cases studied. Some limitations that would need further study are introduced in the end of the paper.     

对沈阳居住建筑自然通风潜力的评估

采用多标准评估方法对沈阳地区居住建筑自然通风潜力进行评估,并把评估结果与其它三个城市哈尔滨,乌鲁木齐和上海的评估结果进行比较。结果得出沈阳地区在四个城市中的自然通风潜力最大。与其它评估方法相比,采用多标准评估方法的结果更加准确。     

Indoor thermal environment of urban residential buildings in China: winter investigation in five major cities

The purposes of this investigation are to look into the actual conditions of urban residential indoor environment in China during the winter season, and to discuss the thermal comfort as well as to understand the possibility of space heating energy conservation. Investigations of indoor thermal environment were carried out in Harbin, Beijing, Xi’an, Shanghai and Hong Kong of China. The results showed that the indoor thermal condition in heating usage zone is good, such as Harbin, Beijing and Xi’an. The indoor thermal comfort is strongly affected by the outdoor climate in non-heating usage zone, such as Shanghai and Hong Kong.     

湿热地区老年人夏季室外热舒适阈值研究

旨在探索湿热地区老年人夏季室外热舒适阈值。以课题示范工程、样本量集中的广州市老人院为研究案例,结合现场实测与问卷调研,获得各气象要素（空气温度、相对湿度、黑球温度、风速）的逐时数据及老年人室外热舒适状况;借助Rayman模型,计算生理等效温度PET,运用SPSS进行回归分析建立老年人室外热舒适评价模型;并评析不同类型测点空间的热环境情况与特点。结论如下：（1）湿热地区夏季老年人室外热环境中性PET值为25.60℃;台湾、香港、广州等湿热气候地区,老年人与混合年龄层中性PET值接近,人群中性PET值具有一定普适性;（2）老年人热感觉中性范围为23.79℃~27.41℃,较混合年龄层窄;老年人室外环境热舒适PET范围为22.70℃~32.53℃,老年人对偏凉感觉（PET=23.10℃）更感舒适;老年人达到90%可接受率的PET范围是22.62℃~31.15℃;（3）老年人夏季热敏感度为3.62PET（℃）/TSV,夏季老年人对室外热环境敏感度明显高于混合年龄层,因此室外热环境设计对老年人具有更大影响;（4）在适当遮荫条件（植物或建筑）下,老年人在夏季依然乐于接受室外阳光辐射;但需综合运用遮阳、通风、降温等设计策略才能满足老年人对热环境的舒适需求。以期为湿热地区室外环境适老设计提供研究方法和设计目标的参考。     

工体、虹口、天河三大体育场改建浅谈——中国世界杯规划战略研究系列(九)

作为中国5座重点城市之三,北京、上海、广州将是未来中国申办世界杯的主办城市热门候选,本文以北京工人体育场、上海虹口足球场和广州天河体育场作为案例,分析其为承办国际足球赛事而进行改建的经验,探讨中国未来通过改建现有体育场满足世界杯赛场需求的潜力。     

西安城市街道“单拱”型林荫街谷 空间冬季微气候测试分析

城市街道空间是城市重要的户外公共生活空间。由行道树和街谷构成的林荫街谷空间对改善街道空间微气候和调控冬夏两季热舒适环境起着重要作用。通过对西安2组城市“单拱”型林荫街谷空间进行冬季微气候实态测试，分析归纳林荫街谷冬季动态热环境的气温变化特征，将“相对热舒适”区域划分为“冷区”(不舒适区)、“暖区”(舒适区)、“日晒区”(愉悦区)，并建立2种热环境动态变化模式，同时基于人体热健康“动态热适应”原理，提出冬季面向健康热环境的街道空间调控策略，对以西安为代表的建筑气候区划中的寒冷地区街道空间气候适应性设计提供了一定的参考价值。     

基于街景大数据的北京、上海街景舒适度评价及比较

基于环境舒适度的理论扩展和街景大数据的应用实践,在城市尺度下对北京和上海2座城市的街景在舒适度感知、影响舒适度的元素以及城市间街景舒适度分布差异方面进行探讨。采用图像语义分割技术,依据街景元素构成特征,通过聚类方法对其进行分类,而后通过网络问卷收集街景舒适度的主观评价。通过相关性分析及数据对比,成功建立了人们对于街景的舒适度感知与客观街道环境元素之间的联系,并区分出对舒适度具有积极和消极影响作用的街景元素;通过将舒适度评价结果在城市空间中进行映射,来反映不同城市之间、城市内部不同区域之间的舒适度分布情况及差异。结果显示北京和上海的街道中的“地形起伏”,均可增强行人的舒适度,而“墙”在2个城市街道中对街道舒适度的作用相反。与以往研究不同的是,“植物”并未显示出对街景舒适度明显的促进作用。就舒适度在城市中的分布来看,北京、上海的老城区舒适度均较低,北京大部分舒适度较低的街道多集中于二环以内的历史性街区,而上海街道的舒适度分布则未呈现出明显规律。基于街景视觉特征的分类方法,归纳总结针对不同类型街道舒适度提升的规划设计建议,为未来能够进一步形成更加精细化、多维度的街景分类标准探索了新的可能。     

门窗玻璃的热工性能对建筑能耗的影响

利用DeST-c软件,通过大量的模拟分析,探讨了不同气候区门窗玻璃的热工性能参数即传热系数(U)和太阳得热系数(SHGC)对建筑能耗的影响.结果表明:从节能方面考虑,对于严寒地区(哈尔滨),应降低K值,增加SHGC值.对于夏热冬暖地区(广州),应降低SHGC值.对于夏热冬冷地区(上海)和温和地区(重庆),应降低K值和SHGC值.而对于寒冷地区(北京),当窗墙比较大时,应降低K值和SHGC值;当窗墙比较小时,应降低K值,增加SHGC值.门窗玻璃的SHGC值全年固定不变对建筑节能不利.理想的门窗玻璃SHGC值应能随季节变化进行相应调整.     

Statistical analyses on summer energy consumption characteristics of residential buildings in some cities of China

The purposes of this paper are to analyse energy consumption characteristics and to find out influence factors of residential energy consumption in summer in typical cities of China. The investigated residences were located in seven cities of five architecture thermotechnical design zones. Questionnaire surveys revealed housing unit characteristics, household characteristics, the possession and utilization of domestic energy consuming appliances and indoor thermal environment in summer. Energy consumption analyses show that summer energy consumption amounts in different cities bear distinct regional characteristics: the household amounts of electricity use are largest in Hongkong, and the values are smaller but still at a high level in Beijing, Shanghai and Changsha, and at the smallest level in Kunming, Harbin and Urumqi, while the difference in gas use is small among these cities. Influence factor analyses show that city locations, housing unit characteristics, the utilization of space coolers and water heaters, household characteristics, and subjective evaluation of indoor thermal environment all contribute to the residential energy consumption in summer when taking all the families in the seven cities as the sample collectivity, while detail analyses for separate cities shows each city has its own characteristics. In Shanghai, the satisfaction rate of thermal environment, the possession and operation of air conditioners and housing unit characteristics greatly affect the summer energy consumption, but the electrical fan is judged as the non-influence factor, while in Urumqi, the possession and operation of electrical fans and the categories of water heaters have remarkable effect, and the influence of housing unit characteristics is also distinct, but the number of air conditioners and their usage contribute little to energy use due to the cool climate.