基于空间行为约束的北京市居民家庭日常出行碳排放的比较分析

Comparative Analysis on CO_2 Emission Per Household in Daily Travel Based on Spatial Behavior Constraints

围绕城市空间结构低碳化的科学命题,从转型期中国城市空间组织制度多元化与个体行为的互动机理出发,对比分析单位制和分区制形成的"社区—家庭"空间行为约束机制作用下的居民日常出行特征及其碳排放。抽样计算,2007年北京市居民家庭工作日日常出行碳排放平均约为2 529.59 g,并在社区尺度上出现了高碳与低碳的显著分化;由于土地混合利用、职住接近、设施供给齐备,内城单位社区及胡同社区对个体出行碳排放有较强的正约束作用;单位制和分区制对个体出行行为有完全异向的碳排放约束响应、作用路径和环境绩效。因此,在社区低碳减排的治理上,应综合考虑小汽车出行使用、出行总量与尺度等家庭出行特征的社区差异,形成针对性的治理设计;在城市布局上,应借鉴单位制的空间组织特点,构造职住再接近,促进低碳出行的紧凑型低碳化的城市空间体系。

The CO2 emission has been increasing significantly in recent years and resulted in severe effects on global environment,and most emitted in the urban region.Therefore,the key to reduce the greenhouse gas rests on the de-carbonization in urban area on transportation and other aspects,influenced by urban form.The authors argued,for urban environment geography and urban planning,how to realize the low-carbonization of urban spatial structure is one critical scientific proposition,including how to evaluate the environment performance by CO2 emission,compare and find out the low-carbon urban structure,urban form and urban spatial institution and so on.Focusing to issues,an emphasis had been placed to discuss the interactive mechanism between the individual behaviors and the various urban spatial structure of China in the transition period.The residential behaviors vary significantly different by communities with dissimilar spatial characteristics.Based on the first-hand investigation data of 600 households＇ daily travel surveys at Beijing in 2007,the CO2 emission per household and other characteristics in daily travels during one workday were calculated,all taken place in the context of the community-family constraint mechanism set by the authors.Subsequently,the CO2 emission was presented by communities,which had been catalogued into four types,including the inner company＇s communities,the block neighborhood,the outer-suburb commercial housing communities and subsidized housing communities.Averagely,2 529.59 g CO2 were emitted during one work-day daily travel per residential household at Beijing in 2007,and the divergence was remarkable in the community level.The inner company＇s communities and the block neighborhood can induce their residents＇ low-carbon emission,whereas the outer-suburb commercial housing communities and subsidized housing communities allocated to low-income citizens often resulted in the high-carbon travels.This community-level divergence was illustrated by the mean comparison and tiered distribution,thus the variance and cluster analysis for travel variables are related to the carbon emission.The viewpoint was that the company and block community exerted notable and positive constraint effects on individual CO2 emission for their characteristics such as mixed land-use,jobs-housings balance and the completeness of facilities provision.In contrast,the communities developed in the appliance of the zoning theory would lead to long-distance travels,expand daily travels＇ scale and promote the individuals to use motor and other the high-carbon travel modes.What deserve attention is that,different from travel distance and travel mode,there is no significant divergence among communities with regards to the number of travels.In conclusion,the company system and zoning system,these two contradictive spatial structure model differ completely in carbon constraint-response and effect path,that is to say that these two main spatial patterns have distinctly different environmental performances.Regarding to the implication of policy,the government should rethink the function zoning,apply the company elements more,and promot the mix land use and comprehensive balance,which are all in accordance with new urbanism and compact city.At the same time,concerned with the governance of low-carbon community,asymmetric-designed policies and controls should be designed deliberatively in view of the household travel characteristic variation by communities.