基于LCZ的广州夏季热岛强度特征分析

城市局地气候分区(Local Climate Zone,LCZ)是按照一定指标对城市空间分区研究城市热环境的通用方法.基于LCZ理论,甄选出广州市9个不同类型的LCZ地块进行空气温度实测,分析多个典型气象日下不同LCZ地块的热岛强度时空特征、气温变化特征和升温冷却率差异.结果 表明:各LCZ地块热岛效应呈现明显的昼弱夜强的日变化规律,日出后逐渐变弱,中午最弱,且部分城市形态区域出现"城市冷岛"的现象,在日落3～5h达到最强,超过4℃;各LCZ地块平均热岛强度夜间差异明显,在0.5～2.3 ℃之间,建筑密度与热岛强度呈正相关.白天差异较小,均在0.5℃左右,高宽比过高的LCZ 1因建筑相互遮阴白天形成"城市冷岛",LCZ A"城市冷岛"效应明显;各LCZ地块日低温差异显著高于日高温差异,且热岛强度日变化特征与升温冷却率变化特征一致.     

城市局地气温对建筑冷负荷的影响

局地气候区(Local Climate Zone,LCZ)是一套用于城市气温研究的客观、标准、通用的局地热气候分类方法。对南京9个不同类型LCZ地块的近地气温进行实测(2016年07月22日至2016年09月30日),然后结合EnergyPlus软件分析局地气温对典型居住建筑和办公建筑冷负荷的影响。结果表明:1)热岛强度夜间显著高于白天;对于整个研究时段的夜间平均热岛强度,紧凑建筑区最高(1.8～1.9℃),其次是开敞中高层建筑区和重工业区(1.4～1.5℃),低层建筑区为0.9～1.1℃;稀疏建筑区最低(0.3℃);热岛强度在少云弱风的典型天气条件下更高;2)与采用郊区气象参数的基准案例相比,整个研究时段各LCZ地块居住建筑的累积冷负荷增幅为8%～17%,办公建筑的累积冷负荷增幅为4%～7%;典型天气条件下的夜间时段各LCZ地块的居住建筑累计冷负荷增幅为8%～26%。     

一个日最大热岛强度诊断方程的检验

应用南京城市气温观测数据对一个2017年最新提出的日最大热岛强度诊断方程进行了检验,这是首次用欧洲之外的城市气温实测数据对该方程进行检验。南京气温观测实验基于城市局地气候分区(Local Climate Zone,LCZ)方法进行,该方法是一种用于城市气温研究的客观标准的局地热气候分类方法。用于本次研究的气温观测数据来源于南京城区7个不同类型的LCZ地块,从2016年7~11月期间挑选出29 d天气特征为晴朗、微风、少云的典型气象日。对比分析了各LCZ地块的日最大热岛强度观测值和基于该诊断方程的计算值,结果表明:该方程的整体精度(r~2=0.46,RMSE=1.08 K,MEAE=0.76 K)接近其在欧洲西北部14个城市的诊断表现(r~2=0.65,RMSE=0.91 K,MEAE=0.58 K),初步表明该方程可用于诊断我国城市的日最大热岛强度。     

局地气候区改变对城市地表热岛强度的影响

统计了地中海气候范围内的米兰、贝鲁特与伊斯坦布尔2000年以及2020年城市发展变化。借助局地气候区系统,探索分析了城市地表热岛强度(Surface Urban Heart Island, SUHI)的时空变化分布。局地气候区框架直观地展示了城市空间形态的变迁,同时更有针对性地表征了地表热岛强度的区域变化特点,为地表热岛强度的缓解提供有效参考依据。结果表明米兰的城市扩张范围最小,产业升级造成的工业园区(LCZ8)更新是城市过去20年来的主要变动,LCZ 2与LCZ 3对LCZ 8的替代创造了更多的人工排热,使当地地表热岛强度平均提升了1.2℃。贝鲁特的扩张规模是3座城市中最大的,其建成类局地气候分类面积提高了约8%。伊斯坦布尔海岸沿线与近郊出现快速城市化的趋势,近郊的建筑密度不断提升,区域内平均提升了1.3℃。总体来看,在夏季地中海城市,与工业排热相比,人工排热也会使区域产生强烈的地表热岛效应。伊斯坦布尔的结果证明了千万人口城市中的局地气候区变化会产生更强烈的地表热岛强度。大都市的交通排热也是影响城市热环境的重要因素。3座城市展示了不同发展阶段下城市面临的热岛效应问题,研究城市变迁将为...     

局域微气候对建筑供暖空调用能的影响

准确的量化城市建筑能源需求有助于实现建筑节能,但鲜有探讨严寒地区局域微气候差异对单体建筑供暖空调用能需求的影响。研究基于局地气候分区（local climate zone, LCZ）体系,采用实测和EnergyPlus模拟结合的方法对以哈尔滨市南岗区14个典型空间的全年逐时空气温度和相对湿度为天气文件的典型单体办公建筑进行了能耗模拟与分析。结果显示不同LCZ类型的建筑供冷供热能耗和逐时冷热负荷均存在显著差异,供热需求明显高于供冷需求,LCZA密林总能耗最高,LCZ2多层高密度总能耗最低;不同地表形态特征对夏季典型日冷负荷的影响大于冬季典型日热负荷的影响;年供热能耗和总能耗与室外气温负相关,年供冷能耗与室外气温和相对湿度不具备线性相关性。     

上海城市热岛效应及风对其影响的研究

利用上海11个区气象观测站2016年8月～2017年7月的观测资料,分析了上海城市热岛的年变化特征及日变化规律,并进一步分析了风对热岛强度及热岛分布的影响。研究发现,上海热岛强度月变化有明显的双峰现象,夏季5月与秋季10月的热岛强度最大,可达1.3℃。冬季及8～9月是热岛的最小段,在0.6℃左右,全年平均的热岛强度约为0.9℃。上海城市热岛的年平均日变化大致为白天低、夜间高的多峰结构,夜间高峰值可达1.2℃。上海风速表现为春冬大夏秋小、白天大夜间小的趋势,经拟合,发现风速与热岛强度存在很好的负相关,秋冬季的拟合误差在0.2℃左右,相关系数可达0.9。此外风向对热岛分布有很大影响,东南风可以降低热岛强度,并使热岛中心向西北方向移动,西北风使热岛强度增大,热岛中心往东南移。     

基于局地气候分区的武汉建成空间近地面风环境异质特征分析

为厘清不同类型建成空间风环境异质特征，本文根据局地气候分区(Local Climate Zone, LCZ)对武汉建成空间进行分类，利用城市气象站点2019年全年风速风向监测数据，探讨建成空间整体风速特征及LCZ类间风速风向特征。结果表明：1)整体上来讲，建成空间对城市背景风具有较大削减作用，不管在何种背景风速段下武汉市建成空间平均风速仅为背景风速的1/3;2)建成空间类型间风速存在差异且在不同背景风速段下保持稳定的规律，风速大小呈现大型低层(LCZ8)>零散建筑(LCZ9)>开敞低层(LCZ6)>开敞中层(LCZ5)>开敞高层(LCZ4)>紧凑中层(LCZ2)>紧凑低层(LCZ3),其中LCZ3以发生静风为主，且全年静风频率高达72%,其他LCZ静风频率在11%～40%之间，皆以发生软风为主；3)同一类型建成空间局地主导风向异质特征较为显著，易受LCZ内部建筑形态及周边建成环境的影响。研究成果为延伸LCZ理论在城市气候环境评估中的应用提供相关参考。     

减弱热岛强度的城市形态布局关键参数与响应机制

基于天津市1992—2013年7景夏季TM遥感影像,分别提取城市形态与反演城市热岛强度,利用ArcGIS与MATLAB等大数据分析计算软件,定量研究城市形态布局与热岛强度的响应机制与参数曲线,提出了热岛强度双指标测度的概念算法,即最高热岛升温和热岛升温总量。结果表明:热岛强度随着城市形态面积的增大而上升,总体上城市形态总面积与最高热岛升温、热岛升温总量都呈线性关系;城市形态离散度和临近度,与最高热岛升温不存在明显相关性,而与热岛升温总量呈线性关系;斑块面积与热岛强度呈正相关,50km2以上的斑块,面积与最高热岛升温呈线性关系,与热岛升温总量呈二次曲线关系;周长面积比与热岛强度呈负相关,与最高热岛升温成S曲线关系,当介于[0.005,0.04]时则与最高热岛升温呈四次曲线关系;斑块分维数与热岛强度呈正相关关系,与最高热岛升温呈线性关系,与热岛升温总量呈三次曲线关系。     

城市热岛空间格局及形态差异化调控策略研究——以广州市中心城区为例

深入研究城市热岛的空间形态差异性对认识城市热岛效应和改善城市微气候具有重大意义。以广州市中心城区为例,运用地域圈层的空间类型识别热岛空间格局,以局地气候分区法(LCZ)为基础提取典型热岛街区进行数据分析,并从用地类型、地表覆盖、建设强度3方面总结空间形态特征。研究表明:研究区由中心向外围呈现出"内外双高"的波浪形热岛空间格局;提取出4种典型热岛街区,分别为高密度居住类、工业类、高密度服务类和设施农业类;建筑密度的两极化、工业用地占比高、不透水地表比例高和植被覆盖率低是造成研究区强热岛的主要原因。基于此提出具有可操作性的形态差异化调控策略,丰富城市热岛空间形态差异性研究成果,为中国湿热地区的城市生态规划建设提供借鉴。     

湿热地区高层住区热环境设计参数对热岛强度的影响研究

减缓住区热岛强度是绿色建筑和生态城市建设的重要内容。以往研究从局部和整体层面对湿热地区住区气温及热岛强度展开测试和研究。本文以广州高层住区为例,在夏季晴热天气条件下开展住区现场实测。测试指标主要包括郊区、城区和住区的气温以及住区热环境设计参数。文章从城区、住区、测点三个尺度,分析探讨气温和热岛强度的变化特征以及形成机制。研究指出,以郊区气象站为基准计算住区热岛强度,因受所在城区局地热岛强度的影响,无法合理评价不同住区热环境设计的优劣,而以城区气象站为基准,可避免局地热岛的干扰,计算和评价更为合理。热环境设计参数,即天空角系数、阴影率和叶面积指数,是影响住区和测点热岛强度的关键因素。热岛强度的定义应取同一尺度或相邻尺度空间的气温差。     

Urban planning indicators,morphology and climate indicators: A case study for a north-south transect of Beijing,China

Eleven sites, representing different urban morphologies across central Beijing, are used to simulate urban heat island effects and explore the relationship between urban planning indicators and climate indicators such as daily maximum and minimum surface temperatures. The results indicate that mesoscale urban planning indicators can explain the majority of the urban climate differences among the sites. For example, green cover ratio and floor area ratio can explain 94.47–98.57% of the variance for daily maximum surface temperature, green cover ratio and building height can explain 98.94–99.12% of the variance for daily minimum surface temperature, and floor area ratio, green cover ratio and building density together can explain 99.49–99.69% of the variance for time of peak surface temperature. Furthermore, green cover ratio is identified as the most significant urban planning indicator affecting the urban thermal environment.     

某水疗会所利用污水热泵供冷供热的可行性分析

分析了重庆市主城区某水疗会所项目利用污水源热泵系统进行空调供冷和卫生热水供应的可行性。通过监测该项目的污水温度、污水流量,对污水的取水、退水和污水处理方案进行了技术论证,同时研究了该项目采用污水源热泵系统的经济性、节能性和环保性。结果表明,本项目采用城市污水供冷供热是可行的。     

基于减缓热岛效应的公园绿地布局 优化研究

城市化进程加快导致城市热岛效应问题日益突出,公园绿地在降温方面具有重要作用,如何通过公园绿地布局以减缓热岛效应是当前值得思考的问题。以福州市主城区为研究区,利用辐射传输方程和泰森多边形分析城市热岛情况及公园绿地布局现状,采用P-中值模型结合城市用地规划确定公园绿地布局优化方案,结果表明:1)福州市主城区的整体温度偏高,其热岛范围达城市总面积的11.78%;2)共提取福州市主城区公园绿地47个,总面积为11.11km2,占主城区总面积的4.47%,公园绿地布局总体不能满足人们的需要;3)利用P-中值模型对公园绿地供需情况进行分析,得出18个公园绿地需要优化,其中包括福州动物园、环南公园等12个一级优化公园绿地,以及屏山公园、琴亭湖公园等6个二级优化公园绿地;4)结合福州市中心城区用地规划,得到50个潜在公园绿地建设点,主要集中于城门镇、盖山镇及新店镇。     

Residential cooling loads and the urban heat island—the effects of albedo

The urban heat island has become the target of recent research aiming at improving urban climates and energy efficiency of cities. In the warm, mid- and low-latitude cities, the typical heat island intensity averages up to 3–5°C on a summer day, adding to discomfort and increasing the air-conditioning loads, whereas in some temperate and cold, high-latitude cities a 2°C heat island is considered as a mild asset in winter. Some of these cities have been built to retain the urban heat. The objective of our ongoing research is to identify ways to mitigate summer heat islands in hot climates, for example by increasing the urban albedo, expanding evaporative surfaces and vegetation covers, and increasing urban thermal mass. From the energy consumption point of view, simple techniques such as these can be effective in reducing air-conditioning costs by modifying and improving the urban micro- and meso-climates.

In this work, we have correlated the residential cooling energy and power consumption in Sacramento, California, with the urban heat island intensity. The effects of selected strategies, such as the ones mentioned above, upon changing the urban micro-climate and reducing the heat island induced cooling loads were simulated. The main focus in this paper is placed on albedo. The simulations were performed using the DOE-2.1C building energy analysis program in conjunction with micro-climate and planetary boundary layer models that predict the effects of albedo modifications on ambient conditions and micro-climates. The simulations indicate that there exists significant potential energy and peak power savings by using such simple conservation strategies. Simulations for Sacramento indicate that whitewashing the buildings can result in direct savings of up to 14% and 19% on cooling peak power and electrical cooling energy, respectively. Modifying the overall urban albedo, in addition to whitewashing, can result in total savings of up to 35% and 62% respectively.     

城市公园降温效益的测度与气候适应性 设计策略

在全球气候变暖和中国城市存量发展的背景下,倡导气候适应性的城市公园设计,成为缓解城市热岛效应的重要手段之一。从公园的降温范围和降温幅度2个方面,提出并定义了城市公园降温效益的测度指标,量化其对城市温度的调节能力,进而探讨有关公园设计要素对公园降温的影响。研究发现：1)城市公园能够在90m范围内产生显著的降温作用,最大降温范围可达500m;2)城市公园降温效益除了受到自身要素影响外,还会受到周边所处建成环境的影响;3)公园设计要素中面积大小、边界形态、植被覆盖度、地形变化、蓝绿空间面积比5个要素对其降温效益的发挥产生影响,且影响多为非线性;4)将降温影响要素的认知用于理想情景模拟,发现高温热点区域的面积减少超过50%。研究进一步加深了对城市公园降温效益的认识,为气候适应性的公园设计在调节城市温度方面提供参考。     

Experimental testing of cool colored thin layer asphalt and estimation of its potential to improve the urban microclimate

Urban Heat Island refers to the temperature increase in urban areas compared to rural settings, exacerbating the energy consumption of buildings for cooling. The use of highly reflective materials in buildings and urban structures reduces the absorbed solar radiation and contributes to mitigate heat island. This paper presents the results of a study aiming to measure and analyze the solar spectral properties and the thermal performance of 5 color thin layer asphalt samples in comparison to a sample of conventional black asphalt. Computational fluid dynamics (CFD) simulation is used for evaluating the thermal and energy impact of applying the samples in outdoor spaces (roads). The spectrophotometric measurements showed that the colored thin layer asphalt samples are characterized by higher values of solar reflectance compared to the conventional asphalt, which is mainly due to their high near infrared solar reflectance. From the statistical analysis of the surface temperatures it was found that all the colored thin layer asphalt samples demonstrate lower surface temperatures compared to conventional asphalt. The maximum temperature difference recorded was for the off-white sample and was equal to 12 °C. The CFD simulation results show that surface and air temperatures are decreased when applying the color thin layer sample.     

城市化对住宅建筑空调负荷的影响

城市化产生热岛效应。利用CTTC(建筑群热常数 )模型对城市化后的建筑群温度进行模拟计算 ,把计算结果作为室外计算温度 ,对一普通住宅建筑空调负荷进行了计算 ,并与根据气象台提供的室外温度计算出来的冷热负荷进行比较。结果表明 ,夏季冷负荷受城市化影响较大 ,当无室内发热量时 ,采用气象台提供的气象参数计算出的夏季冷负荷比按小区温度计算的低 1 0 %～ 35 % ;而冬季热负荷受城市化影响不大 ,二者差别不到 1 0 %。     

Developing a modified typical meteorological year weather file for Hong Kong taking into account the urban heat island effect

Building energy computer simulation software is a useful tool for achieving sophisticated design and evaluation of the thermal performance of buildings. For successful thermal and energy simulation of buildings, it requires hourly weather data such as dry bulb air temperature, relative humidity, solar radiation, wind speed, etc. Nowadays, an urban city faces a problem of an urban heat island which causes the urban area to have a higher air temperature than the rural region. Since the currently available weather dataset used in building simulation software mainly comes from weather stations located in remote and rural areas, the impact of the urban heat island on thermal and energy performance of buildings may not be effectively reflected. This paper reports an approach to construct a modified typical meteorological weather file, taking into account the urban heat island effect in the summer season. Field measurements have been carried out in the summer months and the corresponding urban heat island intensities were then determined. With a morphing algorithm, an existing typical meteorological year weather file was modified. An office building and a typical residential flat were modeled with a renowned building energy simulation program EnergyPlus. Computer simulations were conducted using the existing and modified typical meteorological year weather files. It was found that there was around a 10% increase in air-conditioning demand caused by the urban heat island effect in both cases. The implications of this and further work will also be discussed in this paper.     

城市表面温度与建筑类型关系探讨——以苏州市和张家港市为例

通过遥感影像热红外波段制作亮温图,揭示苏州和张家港两城市的地面温度情况,将城市建筑物按亮温等级划分为高温、较高温、中温等几个类型,发现城市中大型建筑体和建筑物密集群是引起城市热岛效应的主要推手。针对这些建筑物与场地的节能改造、余热利用以及绿化建设是减轻城市热岛效应,改善城市热环境质量的关键措施,今后城市规划应该避免将引起城市明显升温的建筑物和场地置于城市主建成区。     

The 24-h unsteady analysis of air flow and temperature in a real city by high-speed radiation calculation method

Heat island phenomenon is an important issue in environmental studies. Many studies involving observations and simulations have been performed. Computational Fluid Dynamics (CFD) analysis including the effects of solar radiation and longwave radiation heating/cooling are limited in the extreme conditions at midday, when solar radiation intensity are at maximum; and the 24-h unsteady analyses are not done due to the difficulties of the boundary conditions. Authors developed Computer Graphics (CG) method for calculating solar radiation and longwave radiation with high speed, and developed the 24-h unsteady analytical method from the data calculated by Weather Research and Forecasting (WRF). The integrated CFD was applied to the real city. The results showed that the integrated CFD was the useful tool to analyze the heat island phenomena.