An analysis of the bioclimates in different climates and implications for the built environment in China

Underlying trends of long-term summer and winter discomfort in terms of heat and cold stresses in the nine major thermal climate zones and sub-zones across China were investigated using 102-year (1901–2002) weather data. In severe cold climates, winter discomfort dominated (about 66%) and the comfort index (CI) varied from −5 (extremely cold) to +2 (hot). A gradual shift from predominantly negative CI to positive CI was observed as one moved across the climate zones from the north to warmer climates in the south. Temperature rise resulted in less discomfort in the winter and more discomfort in the summer. Though the reduction in cold stress and increase in heat stress were moderate during the 102-year period, the last two decades tended to exhibit the largest changes. It is envisaged that if these trends continue, changes in cold and heat stresses in the 21st century would be much greater than those experienced during the 20th century. This could have significant implications for building designs and energy use in the built environment.     

Heat and cold stresses in different climate zones across China: A comparison between the 20th and 21st centuries

Summer and winter discomfort in terms of heat and cold stresses in the nine major architectural climate zones and sub-zones across China in the 21st century were investigated using predictions from general circulation models for the low and medium emissions scenarios. For the six severe cold and cold climate zones in the north, reductions in cumulative cold stress outweighed the increase in cumulative heat stress resulting in an overall decreasing trend in the annual cumulative stress, and vice versa for the other three warmer climate zones in the south. Compared with the 20th century, significant reduction in the cumulative cold stress was observed across the six zones in severe cold and cold climates, ranging from 15.8 in cold-III to 42.3 in severe cold-II. There were modest increases in the cumulative heat stress from 0.3 in cold-II to 12.3 in cold-III. For the warmer climates in the south, reduction in cumulative cold stress ranged from 7.6 in hot summer and warm winter (HSWW) to 10.3 in hot summer and cold winter, while cumulative heat stress increased from 9.9 in the mild zone to 30.6 in HSWW. A reduction in cold stress would result in less winter heating and an increase in heat stress more cooling requirement.     

Different glazing systems and their impact on human thermal comfort—Indian scenario

In the present communication, fifteen different glazing systems ranging from 3 mm single glazed clear glass to double glazed with low-e and solar control coating, have been analysed in terms of their human thermal comfort impact. Thermal comfort is measured in term of PMV (predicted mean vote) and PPD (predicted percentage of dissatisfied). Study encompasses all the six climatic zones of India. By using OPTICS 5.0 and WINDOW 5.0, U-values, solar heat gain coefficient, inside glazing surface temperatures and inside solar radiation have been computed. Depending upon different climatic zones, six sets of different design conditions, in terms of ambient temperatures, solar radiation and wind velocity, have been chosen. Typical values of metabolic rate and clothing insulation taken are 1.2 met and 0.5 clo for summer and 1.0 met and 1.0 clo for winter, respectively. Inside room air velocity is taken as 0.15 m s⁻¹ round the year. Room temperature is taken as 20 °C in winter and 25 °C in summer. It is found that for cold station (e.g. Leh) all glazings except solar control glazings, ensure thermal comfort and total PPD is less than 10% (|PMV|?0.5). For warm and hot climates, solar control glazings are thermally suitable. Results for winter night of Delhi shows that all the 15 glazings are inadequate for thermal comfort and PPD, due to cold feeling, varies between 27% and 33% approximately.     

上海地区高校学生宿舍太阳能热水系统一体化设计研究

本文从分析上海地区太阳能资源入手,说明了上海地区高校学生宿舍应用太阳能热水技术的必要性和可行性,分析了上海地区高校学生宿舍太阳能热水系统一体化设计的几个关键问题,包括集热器与屋面结合方式、集热器方位与角度确定、集热器选型及面积确定、集热器安装位置确定等内容。得出的结论对同类项目有一定的参考价值,对其他夏热冬冷地区的太阳能热水系统与高校宿舍一体化设计也有一定的借鉴意义。     

Revision of the Trombe wall calculation method proposed by UNE-EN ISO 13790

The European and International Standard UNE-EN ISO 13790 presents a set of calculation methods for the evaluation and design of energy and thermal performance of buildings. These methods have diverse range of details for calculating the energy use of heating and cooling in different building zones, as well as for calculating the heat transfer and solar heat gains of special elements, such as ventilated solar walls (Trombe walls). In this article, the authors have revised the aforementioned document in order to check the proposed mathematical models and their implementation within Mediterranean climates. This assessment pinpoints the existence of some errors in the equations provided in EN ISO 13790 under steady state conditions. Concurrently, the corrected equations are shown and new correlations are proposed for the ratios δ and ω which are more suitable for Mediterranean climates.     

Thermal design standards for energy efficiency of residential buildings in hot summer/cold winter zones

Factors such as solar heat gain in summer, heat loss in winter, and natural ventilation in transitional seasons must be considered when designing energy-efficient residential buildings for hot summer/cold winter zones. In this paper, the rationale for defining thermal design of energy-efficient buildings is discussed based on results of field tests on pilot buildings and calculations for typical buildings.     

Impacts of vegetation on residential heating and cooling

Computer simulation has been used to test the effects of irradiance and wind reductions on the energy performance of similar residences of 143 m² in four U.S. cities — Madison, Salt Lake City, Tucson and Miami — representing four different climates. Irradiance reductions from vegetation were modeled using SPS, which simulates shade cast from plants on buildings, and MICROPAS, a microcomputer-based energy analysis program. Space cooling costs were found to be most sensitive to roof and west wall shading, whereas heating costs were most sensitive to south and east wall shading. Irradiance reductions were shown to substantially increase annual heating costs in cold climates ($128 or 28% in Madison), and reduce cooling costs in hot climates ($249 or 61% in Miami). Dense shade on all surfaces reduced peak cooling loads by 31% – 49% or 3108 – 4086 W. A 50% wind reduction was shown to lower annual heating costs by $63 (11%) in Madison, and increased annual cooling costs by $68 (15%) in Miami. Planting designs for cold climates should reduce winter winds and provide solar access to south and east walls. This guideline also applies for temperate climates, however it is also important to avoid blocking summer winds. In hot climates, high-branching shade trees and low ground covers should be used to promote both shade and wind.     

Sensitivity of the total heat loss coefficient determined by the energy signature approach to different time periods and gained energy

In order to identify buildings that have energy saving potential there is a need for further development of robust methods for evaluation of energy performance as well as reliable key energy indicators. To be able to evaluate a large database of buildings, the evaluation has to be founded on available data, since an in-depth analysis of each building would require large measurement efforts in terms of both parameters and time. In practice, data are usually available for consumed energy, water, and so on, namely consumption that the tenants or property holder has to pay for. In order to evaluate the energy saving potential and energy management, interesting key energy indicators are the total heat loss coefficient K_tot (W/K), the indoor temperature (T_i), and the utilisation of the available heat (solar radiation and electricity primarily used for purposes other than heating). The total heat loss coefficient, K_tot, is a measure of the heat lost through the building's envelope, whereas T_i and the gained energy reflect the user's behaviour and efficiency of the control system.In this study, a linear regression approach (energy signature) has been used to analyse data for 2003-2006 for nine fairly new multifamily buildings located in the Stockholm area, Sweden. The buildings are heated by district heating and the electricity used is for household equipment and the buildings’ technical systems. The data consist of monthly energy used for heating and outdoor temperature together with annual water use, and for some buildings data for household electricity are also available. For domestic hot water and electricity, monthly distributions have been assumed based on data from previous studies and energy companies. The impact on K_tot and T_i of the time period and assumed values for the utilised energy are investigated.The results show that the obtained value of K_tot is rather insensitive to the time period and utilised energy if the analysis is limited to October-March, the period of the year when the solar radiation in Sweden yields a minor contribution to heating. The results for the total heat loss coefficient were also compared to the calculations performed in the design stage; it was found that K_tot was on average 20% larger and that the contribution to heating from solar radiation was substantially lower than predicted. For the indoor temperature, however, the utilised energy had a large impact.With access to an estimate of K_tot and T_i, an improved evaluation of the energy performance may be achieved in the Swedish real estate market. At present the measure commonly used, despite the fact that monthly data is available, is the annual use of energy for space heating per square metre of area to let.     

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.     

寒冷地区太阳能炕采暖系统

针对我国东北地区农村采用炕采暖的传统生活习惯,设计了一种太阳能炕采暖系统。该系统充分体现了传统炕采暖的优点,将蓄热池与火炕相结合,利用太阳能采暖低温水系统蓄热供暖,夏季可以提供生活热水,冬季可以同时供应热水和暖气。太阳炕下设有烟气、烟道,综合利用炊事和补燃烟气余热,达到节能的效果。     

寒冷地区太阳能炕采暖系统

针对我国东北地区农村采用炕采暖的传统生活习惯,设计了一种太阳能炕采暖系统。该系统充分体现了传统炕采暖的优点,将蓄热池与火炕相结合,利用太阳能采暖低温水系统蓄热供暖,夏季可以提供生活热水,冬季可以同时供热,太阳炕下设有烟气烟道,综合利用炊事和补燃烟气余热,达到节能的效果。     

太阳能-地源热泵系统的运行模拟

以济南市某工程为例,使用DeST软件对该工程进行年逐时负荷模拟,得到冷负荷峰值为313.3 kW,热负荷峰值为293.7 kW,累计年排热量为166 451 kW·h,累计年提热量为210 380 kW·h,热不平衡率为20.88%。利用TRNSYS软件建立了太阳能-地源热泵系统动态模型,并进行模拟分析。当地土壤初始温度均为15.3℃,复合系统的模拟结果显示系统运行20年,地温均值一直保持在14.8~16.4℃的稳定范围内。研究表明:太阳能-地源热泵复合系统具有良好的蓄热能力,提高了太阳能利用率,可有效解决寒冷地区地源热泵的冷热不平衡问题,是解决严寒地区供暖问题的一个重要途径。     

兰州地区地源热泵与太阳能联合空调系统方案的评价

针对兰州地区冬冷夏凉的气候特点,研究了地源热泵系统与太阳能热水系统联合运行的新型空调系统在该地区的应用。太阳能热水系统可以解决地埋管换热系统冬季吸热与夏季排热不平衡的问题,保证地源热泵系统的稳定高效运行。以兰州新区地源热泵工程为例介绍了太阳能如何与地源热泵匹配的方案,并且对比了联合空调系统与常规空调的运行费用,表明该系统具有技术可行性,可以推广应用。     

夏热冬冷地区屋顶对建筑能耗的影响

使用清华大学开发的建筑能耗模拟软件DeST-h,对宁波地区一幢典型居住建筑的能耗随屋顶传热系数的变化规律进行模拟分析,并通过试验,测试了屋顶温度及热流的变化。结果表明:降低屋顶传热系数对降低采暖能耗效果明显,对降低夏季空调能耗效果不明显,采用架空屋顶能明显降低空调能耗。这对夏热冬冷地区的建筑设计具有一定的指导作用。     

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.     

Ideal thermophysical properties for free-cooling (or heating) buildings with constant thermal physical property material

Free-cooling is understood as a means to store outdoors coolness during the night, to supply indoors cooling during the day in summer, while free-heating is understood as a means to store the solar radiation during daytime, to supply indoors heating during the night in winter. In principle, free-cooling or free-heating can make the indoor air temperature in the comfortable region all the year if the thermophysical properties of building envelope material are in the desired range (defined as ideal thermophysical properties in this paper). Those properties are obviously related to the outdoor climate condition, internal heat source intensity, building configuration, ventilation mode etc. For a given region and a given building, the critical values of those ideal thermal physical properties can be determined through modeling and simulation. Two parameters, I_win and I_sum, are defined to describe the overcool degree in winter and the overheat degree in summer, respectively. To illustrate, the critical values of thermophysical properties of building envelope of a building located in Beijing are obtained through modeling and simulation. The simulated results are validated with experiments. The model, the methodology and the results are helpful for selection of suitable building envelope materials and for design of energy efficient buildings.     

A holistic approach to energy efficient building forms

Minimizing energy consumption in buildings has become an important goal in architecture and urban planning in recent years. Guidelines were developed for each climatic zone aiming at increasing solar exposure for buildings in cold climates and at reducing solar exposure for buildings in hot climates. This approach usually plans for the season with the harshest weather; often forgetting that temperatures in cities at latitude 25° can drop below thermal comfort limits in winter and that temperatures in cities at latitude 48° often rise above thermal comfort limits in summer. This paper argues that a holistic approach to energy efficient building forms is needed. It demonstrates a generic energy efficient building form derived by cutting solar profiles in a conventional block. Results show that the proposed building form, the Residential Solar Block (RSB), can maximize solar energy falling on facades and minimize solar energy falling on roofs and on the ground surrounding buildings in an urban area in winter; thus maximizing the potential of passive utilization of solar energy. The RSB also supports strategies for mitigating the urban heat island through increased airflow between buildings, the promotion of marketable green roofs and the reduction of transportation energy.     

CHEOPS: a simplified tool for thermal assessment of Mediterranean residential buildings in hot and cold seasons

The Mediterranean climate is characterized by a high level of the solar resource in winter and some coolness of the nights in summer, which offer a good opportunity for thermal comfort achievement at low energy cost and reduced CO₂ emissions, provided that an appropriate design of the building envelope is adopted. It has thus been decided to implement some regulations in three countries of North-Africa for controlling the heating and cooling loads. The study described in this paper has been conducted in the frame of this project. It has two objectives: to define adequate indicators for the thermal performance of buildings during both the cold season and the hot one, and to develop a standard calculation procedure for these indicators. The developed procedure, CHEOPS, is fast and requires minimum input data; it is very easy to use, the steps for calculating the cooling and heating coefficients being almost the same. The transmission losses and the solar gains are clearly identified; this fact can contribute to a better understanding by the designer of the effect of each parameter, leading him towards the appropriate trade-offs between summer and winter considerations.     

基于主成分-聚类分析法的建筑节能气候区划

通过分析影响建筑冷热耗量的气候指标,提出了以采暖度日数HDD18、空调度日数CDD26、最冷月平均温度、最热月平均温度、冬季太阳辐射热量、夏季太阳辐射热量、冬季含湿量和夏季含湿量8个气候指标作为建筑节能气候区划指标,采用主成分分析与聚类分析相结合的区划方法对我国270个城市进行了建筑节能气候区划,划分为严寒干热高辐区、严寒凉爽高辐区、严寒无夏区、寒冷微热区、温和炎热湿润区、温和凉爽区和阴冷湿热区,介绍了这7个气候区的主要气候特征和主要的地理范围,明确了各区的建筑节能重点和适宜的技术策略。     

夏热冬冷地区实施集中供热面临的问题

分析夏热冬冷地区对集中供热的需求。通过对合肥市集中供热现状的分析,总结夏热冬冷地区实施集中供热面临的问题,对适用的热源方案及选择原则进行了探讨。