城市住宅建筑系统流量-存量动态模拟——以北京市为例

地面建筑物的累积与更新是城市化过程的结果与显性特征之一。城市建筑系统在不同层面上与外部环境系统进行着物质能量交换,对这种交互产生的资源压力与环境胁迫的关注,使其成为城市代谢研究领域中的热点问题。系统分析与模拟城市建筑物流量-存量的动态变化过程及其资源环境响应,对于揭示城市建筑系统代谢机理,提高城市总体规划精准性、强化资源系统韧性管理、提升废弃物处置效率等宏观战略具有重要意义。以北京市为例,基于Stella建模平台,构建了城市居民住宅建筑系统流量-存量的动态模拟模型,定量模拟了不同管理情景下钢材需求量与建筑拆除垃圾产生量的变化区间。结果表明:(1)基准情景下,北京住宅建筑新建流量前期增速较快,2005年达到峰值3024.1万m~2,而拆除流量约于2057年达到峰值,拆除面积为2073.14万m~2;城市住宅建筑存量最高值出现在2075年左右,面积为7.51亿m~2;(2)与基准情景相比,如果人均住宅建筑面积提高到45 m~2,从现在到模拟期结束(2019—2100)将增加钢铁需求量3251.65万t;而如果延长住宅建筑寿命至设计值,同期可减少钢铁需求量3022.9万t;(3)基准情景、大面积情景以及长寿命情景下,北京市城镇住宅建筑拆除垃圾峰值产生量分别为0.29亿t、0.39亿t、0.20亿t,政府管理部门应采取有针对性的应对措施,提前做出综合利用和处理处置方案。     

The Growth of Urban Building Stock: Unintended Lock‐in and Embedded Environmental Effects

Building stocks constitute enduring components of urban infrastructure systems, but little research exists on their residence time or changing environmental impacts. Using Los Angeles County, California, as a case study, a framework is developed for assessing the changes of building stocks in cities (i.e., a generalizable framework for estimating the construction and deconstruction rates), the residence time of buildings and their materials, and the associated embedded environmental impacts. In Los Angeles, previous land‐use decisions prove not easily reversible, and past building stock investments may continue to constrain the energy performance of buildings. The average age of the building stock has increased steadily since 1920 and more rapidly after the post–World War II construction surge in the 1950s. Buildings will likely endure for 60 years or longer, making this infrastructure a quasi‐permanent investment. The long residence time, combined with the physical limitations on outward growth, suggest that the Los Angeles building stock is unlikely to have substantial spatial expansion in the future. The construction of buildings requires a continuous investment in material, monetary, and energetic resources, resulting in environmental impacts. The long residence time of structures implies a commitment to use and maintain the infrastructure, potentially creating barriers to an urban area's ability to improve energy efficiency. The immotility of buildings, coupled with future environmental goals, indicates that urban areas will be best positioned by instituting strategies that ensure reductions in life cycle (construction, use, and demolition) environmental impacts.     

Tracking Construction Material over Space and Time: Prospective and Geo‐referenced Modeling of Building Stocks and Construction Material Flows

Construction material plays an increasingly important role in the environmental impacts of buildings. In order to investigate impacts of materials on a building level, we present a bottom‐up building stock model that uses three‐dimensional and geo‐referenced building data to determine volumetric information of material stocks in Swiss residential buildings. We used a probabilistic modeling approach to calculate future material flows for the individual buildings. We investigated six scenarios with different assumptions concerning per‐capita floor area, building stock turnover, and construction material. The Swiss building stock will undergo important structural changes by 2035. While this will lead to a reduced number in new constructions, material flows will increase. Total material inflow decreases by almost half while outflows double. In 2055, the total amount of material in‐ and outflows are almost equal, which represents an important opportunity to close construction material cycles. Total environmental impacts due to production and disposal of construction material remain relatively stable over time. The cumulated impact is slightly reduced for the wood‐based scenario. The scenario with more insulation material leads to slightly higher material‐related emissions. An increase in per‐capita floor area or material turnover will lead to a considerable increase in impacts. The new modeling approach overcomes the limitations of previous bottom‐up building models and allows for investigating building material flows and stocks in space and time. This supports the development of tailored strategies to reduce the material footprint and environmental impacts of buildings and settlements.     

Stemwood volume increment changes in European forests due to climate change—a simulation study with the EFISCEN model

This paper presents the results of a modelling study of future net annual increment changes in stemwood of European forests owing to climate change. Seven process‐based growth models were applied to 14 representative forest sites across Europe under one climate change scenario. The chosen scenario was the HadCM2 run, based on emission scenario IS92a, and resulted in an increase in mean temperature of 2.5 °C between 1990 and 2050, and an increase in annual precipitation of 5–15%. The information from those runs was incorporated in a transient way in a large‐scale forest resource scenario model, EFISCEN (European forest information scenario). European scale forest resource projections were made for 28 countries covering 131.7 million ha of forest under two management scenarios for the period until 2050. The results showed that net annual increments in stemwood of European forests under climate change will further increase with an additional 0.9 m³ ha^?1 y^?1 in 2030 compared to the ongoing increase under a current climate scenario, i.e. an extra 18% increase. After 2030 the extra increment increase is reduced to 0.79 m³ ha^?1 y^?1 in 2050. Under climate change, absolute net annual increments will increase from the present 4.95, on average for Europe, to 5.93 m³ ha^?1 y^?1 in 2025. After 2025, increments in all scenarios start to decline owing to ageing of the forest and the high growing stocks being reached. The results of the present study are surrounded by large uncertainties. These uncertainties are caused by unknown emissions in the future, unknown extent of climate change, uncertainty in process‐based models, uncertainty in inventory data, and uncertainty in inventory projection. Although the results are thus not conclusive, climate change may lead to extra felling opportunities in European forests of 87 million m³y^?1. Because Europe's forests are intensively managed already, management may adapt to climate change relatively easily. However, this study also indicates that climate change may lead to a faster build‐up of growing stocks. That may create a less stable forest resource in terms of risks to storm damage.     

Greening China's Wastewater Treatment Infrastructure in the Face of Rapid Development: Analysis Based on Material Stock and Flow through 2050

Wastewater treatment infrastructure (WWTI) construction in China has entered an accelerated stage of development in recent years as a result of rapid economic growth, urbanization, and the demand for improving water quality. As a result, a large amount of resources and materials will be allocated for the WWTI, and it is particularly important to find ways to reduce resource consumption effectively so that social dematerialization and sustainable development can be achieved. In this study, we employed the dynamic material flow model to estimate the material flows and stocks of WWTIs and the associated carbon dioxide (CO₂) emissions through 2050, considering effects of a rise in water consumption, a longer lifetime, and an increased material recycling rate. Our results indicate that material consumption in WWTIs will increase rapidly through 2025 to meet the needs of the increased volume of discharged wastewater as well as to overcome the shortage of existing wastewater treatment plants. In contrast with the moderate effects of rise in water consumption, prolonging the lifetime will greatly reduce material consumption in WWTI construction during the period 2030–2050, and approximately 60% of the total material input will be saved in the medium‐lifetime scenario, compared with the short‐lifetime scenario. Material output and CO₂ emissions associated with WWTIs will be reduced by 87% and 37%, respectively, in the medium‐lifetime scenario, compared with the short‐lifetime scenario, under high‐water‐consumption growth. Our results highlight the great importance of pipeline construction and cement consumption in resource consumption associated with WWTI construction in China. Moreover, this study also examined the potential ways to reduce material consumption in WWTI construction in the context of the demand chain, the design, construction, operation and management, and demolition.     

Life cycle assessment and cost analysis of residential buildings in south east of Turkey: part 1—review and methodology

Purpose

Buildings are responsible for more than 40 % of global energy used, and as much as 30 % of global greenhouse gas emissions. In order to quantify the energy and material inputs and environmental releases associated with each stage of construction sector, life cycle energy, greenhouse gas emissions, and cost analysis of contemporary residential buildings have been conducted within two parts.

Methods

This paper is the first part of the study which includes the literature review and methodology used for such a comprehensive analysis. It was determined that there are three basic methods used in life cycle analysis: process analysis, input–output (I–O) analysis, and hybrid analysis. In this study, Inventory of Carbon and Energy (ICE) is used for the calculation of primary energy requirements and greenhouse gas emissions. The second part of this study is about the application of the methodology which considers two actual buildings constructed in Gaziantep, Turkey.

Results and discussion

The proposed research focused on building construction, operating, and demolition phases. Energy efficiency, emission parameters, and costs are defined for the building per square meter basis. It is seen that the primary energy use and emissions of residential buildings around the world falls in the range of about 10 to 40 GJ/m² and 1–10 t CO₂/m² respectively.

Conclusions

The literature survey demonstrates that there are limited number of studies about life cycle cost assessment (LCCA) of residential buildings in the world. It was decided to use the ICE database as it is one of the most comprehensive databases for building materials, globally. The results of the study show that minimizing energy, material, and land use by considering potential impacts to the environment on a life cycle basis are the basic steps in designing an energy-efficient and environmental-friendly building.

     

Health and Economic Burden of Obesity in Brazil

Introduction

Higher and lower-middle income countries are increasingly affected by obesity. Obesity-related diseases are placing a substantial health and economic burden on Brazil. Our aim is to measure the future consequences of these trends on the associated disease burden and health care costs.

Method

A previously developed micro-simulation model is used to project the extent of obesity, obesity-related diseases and associated healthcare costs to 2050. In total, thirteen diseases were considered: coronary heart disease, stroke, hypertension, diabetes, osteoarthritis, and eight cancers. We simulated three hypothetical intervention scenarios: no intervention, 1% and 5% reduction in body mass index (BMI).

Results

In 2010, nearly 57% of the Brazilian male population was overweight or obese (BMI ≥25 kg/m²), but the model projects rates as high as 95% by 2050. A slightly less pessimistic picture is predicted for females, increasing from 43% in 2010 to 52% in 2050. Coronary heart disease, stroke, hypertension, cancers, osteoarthritis and diabetes prevalence cases are projected to at least double by 2050, reaching nearly 34,000 cases of hypertension by 2050 (per 100,000). 1% and 5% reduction in mean BMI will save over 800 prevalence cases and nearly 3,000 cases of hypertension by 2050 respectively (per 100,000). The health care costs will double from 2010 ($5.8 billion) in 2050 alone ($10.1 billion). Over 40 years costs will reach $330 billion. However, with effective interventions the costs can be reduced to $302 billion by 1% and to $273 billion by 5% reduction in mean BMI across the population.

Conclusion

Obesity rates are rapidly increasing creating a high burden of disease and associated costs. However, an effective intervention to decrease obesity by just 1% will substantially reduce obesity burden and will have a significant effect on health care expenditure.     

Opportunities and challenges of sustainable agricultural development in China

This paper introduces the concepts and aims of sustainable agriculture in China. Sustainable agricultural development comprises sustainability of agricultural production, sustainability of the rural economy, ecological and environmental sustainability within agricultural systems and sustainability of rural society. China's prime aim is to ensure current and future food security. Based on projections of China's population, its economy, societal factors and agricultural resources and inputs between 2000 and 2050, total grain supply and demand has been predicted and the state of food security analysed. Total and per capita demand for grain will increase continuously. Total demand will reach 648 Mt in 2020 and 700 Mt in 2050, while total grain yield of cultivated land will reach 470 Mt in 2010, 585 Mt in 2030 and 656 Mt in 2050. The per capita grain production will be around 360kg in the period 2000-2030 and reach 470kg in 2050. When productivities of cultivated land and other agricultural resources are all taken into consideration, China's food self-sufficiency ratio will increase from 94.4% in 2000 to 101.3% in 2030, suggesting that China will meet its future demand for food and need for food security. Despite this positive assessment, the country's sustainable agricultural development has encountered many obstacles. These include: agricultural water-use shortage; cultivated land loss; inappropriate usage of fertilizers and pesticides, and environmental degradation.     

Life-cycle assessment and cost analysis of residential buildings in South East of Turkey: part 2—a case study

Purpose

Residential buildings play an important role in consumption of energy resources. About 40 % of all primary energy is used in buildings all over the world. This paper is the second part of the study on the life-cycle energy (LCEA), emissions (LCCO₂A) and cost (LCCA) assessment of two residential buildings constructed in urban and rural areas.

Methods

In the first part, the methodology, formulations and procedure for such a comprehensive analysis are provided, while this paper provides an application of the methodology that considers two actual buildings located in Gaziantep, Turkey. The proposed model focused on building construction, operation and demolition phases to estimate energy use, carbon emissions and costs per square meter over a 50-year lifespan. The optimum thickness of insulation used to reduce energy consumption and emissions per square meter is determined.

Results and discussion

It is found that the operating phase is dominant in both urban and rural residential buildings and contributes 87–85 % of the primary energy requirements and 88–82 % of CO₂ emissions, respectively. Life-cycle greenhouse gas emissions were 5.8 and 3.9 tons CO₂ eqv. for BT1 and BT2, respectively. It is calculated that the life-cycle energy consumption and CO₂ emissions of the residential buildings can be reduced by up to 22.8 and 23.4 %, respectively, by using a proper insulation material for the external walls. The life-cycle cost, consisting of mortgage, energy, maintenance, service and demolition payments are calculated to be 7.28 and 1.72 million USD for BT1 and BT2, respectively.

Conclusions

Building envelope developments, such as better wall insulation, provide noteworthy potential energy savings and contribute to the reductions from cooling and space heating. Therefore, primary strategies and technologies needed for efficient buildings include optimal insulation of external walls. The economic insulation thickness of the residential buildings in Gaziantep is determined to be 80 mm by using a life-cycle cost analysis. The results show that because of the differences in building structures and living standards, life-cycle energy intensity and CO₂ emissions in urban residential buildings are 29 and 25 % higher than in rural conditions.

     

Methodology for determining the ecological footprint of the construction of residential buildings in Andalusia (Spain)

Construction activity is now a major consumer of natural resources. As a general rule, resource consumption has been evaluated through methodologies related to Life Cycle Analysis. This research is proposed to integrate the Ecological Footprint indicator into the building sector: to observe the difficulties and the benefits it can generate relative to other indicators. To this end, prior knowledge related to the Ecological Footprint indicator must first be adapted to the residential sector, by analyzing the construction of buildings, and secondly a calculation methodology is established in order to quantitatively determine what impacts are generated by industry according to the Ecological Footprint indicator. This methodology applies the indicator to resources used (energy, water, labour, construction materials, etc.) and to waste generated in the construction of residential buildings.The methodology is applied to a case study corresponding to the urbanization and building construction of a representative building type in Andalusia (Spain) when the building is in the planning stage. The final result is 0.384 gha/year/m².     

基于建筑容量的城市建设用地碳汇量核算方法

城市建设中的矿物质材料开发利用活动不仅导致大量碳排放,也产生了碳吸收.以往建筑矿物质材料的碳吸收过程一直没有得到重视和科学量化.本研究采用遥感影像阴影高度反演技术,提取地块的建筑容量,识别建筑类型,以此为依据确定矿物材料用量及碳含量参数,采用热重分析法测定碳化率,基于以上步骤构建城市建筑碳汇量的核算方法,并选取沈阳市蒲河新来测试这一核算方法,同时进行不确定性分析.结果表明: 1996—2016年,沈阳市蒲河新城各类型建筑产生的碳汇总量依次为:居住建筑>公共服务建筑>其他类建筑>商业金融建筑>工业建筑;各类建筑用地的碳汇容积率依次为:商业金融建筑>居住建筑>公共服务建筑>其他类建筑>工业建筑.本研究构建的基于建筑容量提取的城市尺度的建筑碳汇量核算方法,可以快速准确地估算不同类型城市建设用地无机材料产生的碳汇量.在城市自然碳汇有限条件下,利用建筑碳汇增加城市碳汇量,能够为我国城市低碳发展提供新的思路.     

Toward a low-carbon and circular building sector: Building strategies and urbanization pathways for the Netherlands

Buildings are an important part of society's environmental impacts, both in the construction and in the use phase. As the energy performance of buildings improve, construction materials become more important as a cause of environmental impact. Less attention has been given to those materials. We explore, as an alternative for conventional buildings, the use of biobased materials and circular building practices. In addition to building design, we analyze the effect of urbanization. We assess the potential to close material cycles together with the material related impact, between 2018 and 2050 in the Netherlands. Our results show a limited potential to close material cycles until 2050, as a result of slow stock turnover and growth of the building stock. At present, end-of-life recycling rates are low, further limiting circularity. Primary material demand can be lowered when shifting toward biobased or circular construction. This shift also reduces material related carbon emissions. Large-scale implementation of biobased construction, however, drastically increases land area required for wood production. Material demand differs strongly spatially and depends on the degree of urbanization. Urbanization results in higher building replacement rates, but constructed dwellings are generally small compared to scenarios with more rural developments. The approach presented in this work can be used to analyze strategies aimed at closing material cycles in the building sector and lowering buildings' embodied environmental impact, at different spatial scales.     

Modeling copper demand in China up to 2050: A business‐as‐usual scenario based on dynamic stock and flow analysis

In this paper, we develop a dynamic stock model and scenario analysis involving a bottom‐up approach to analyze copper demand in China from 2005 to 2050 based on government and related sectoral policies. The results show that in the short‐term, China's copper industry cannot achieve a completely circular economy without additional measures. Aggregate and per capita copper demand are both set to increase substantially, especially in infrastructure, transportation, and buildings. Between 2016 and 2050, total copper demand will increase almost threefold. Copper use in buildings will stabilize before 2050, but the copper stock in infrastructure and transportation will not yet have reached saturation in 2050. The continuous growth of copper stock implies that secondary copper will be able to cover just over 50% of demand in 2050, at best, even with an assumed recycling rate of 90%. Finally, future copper demand depends largely on the lifetime of applications. There is therefore an urgent need to prolong the service life of end‐use products to reduce the amount of materials used, especially in large‐scale applications in buildings and infrastructure.     

北京市住宅建筑生命周期碳足迹

从生命周期角度看,建筑碳足迹与能源和建材生产系统具有密切关系。随着技术的进步和节能政策的推进,中国能源的生产和使用,以及建材生产过程中的环境排放都随着时间在持续降低,这将间接地影响到建筑的环境表现。依据1990—2010年期间每5a的中国能源与建材生命周期清单数据,对北京市20年间住宅建筑系统开展生命周期评价和碳足迹核算,以揭示北京市住宅建筑系统的环境负荷变化特征。结果表明,北京市住宅建筑生命周期碳足迹随时间推移呈现降低趋势,主要来自能源系统和建材生产系统的碳减排贡献。不同结构建筑的碳足迹尽管有差异,但也呈现了相似的下降趋势。从生命周期阶段看,建筑碳足迹主要体现在建筑使用阶段和建材生产阶段。尽管建筑使用阶段的节能对于降低建筑生命周期碳足迹具有重要贡献,但节能在经济成本及环境成本方面而言是有限度的。在可持续的环境政策管理制定中,应从生命周期角度,统筹考虑协调各行业减碳的协调发展。论文同时也验证了在生命周期评价中考虑时间变量将有助于更好地利用生命周期评价结果支持环境可持续管理。结论对于城市规划的政策制定、量化环境表现是有益的。     

Midlife obesity and dementia: Meta‐analysis and adjusted forecast of dementia prevalence in the united states and china

Objective:

Obesity is a risk factor of dementia. Current forecasts of dementia prevalence fail to take the rising obesity prevalence into account.

Design and Methods:

Embase and Medline were searched for observational studies on the association between overweight (BMI 25‐30 kg/m²) or obesity (BMI > 30 kg/m²) and dementia and pooled the effect sizes by meta‐analysis. The population attributable risk (PAR) was calculated for different time points and adjusted them for confounders. Based on current prevalence rates of dementia and demographic forecasts, patient numbers were calculated and adjusted by the growth rates of PAR.

Results:

Compared to normal weight, midlife obesity increases the risk of dementia later in life (BMI 25‐30: RR = 1.34 [95% CI 1.08, 1.66], BMI > 30: RR = 1.91 [1.4, 2.62]). If obesity is included into forecast models, the prevalence of dementia is estimated to be 7.1 million (6.9, 7.3) and 11.3 million (10.9, 11.7) for the United States in 2030 and 2050, respectively. In China, the estimate is 13.1 million (12.8, 13.3) in 2030 and 26.2 million (25.1, 27.4) in 2050. These figures are 9% and 19% higher for the United States and China, respectively, than forecasts that rely solely on the demographic change.

Conclusion:

The past and ongoing increase in midlife obesity prevalence will contribute significantly to the future prevalence of dementia and public health measures to reduce midlife obesity are simultaneously primary prevention measures to reduce the risk of dementia.     

LCA of concrete and steel building frames

The effects on the external environment of seven concrete and steel building frames representative of present-day building technology in Sweden were analysed using LCA methodology. Objects of the study included frame construction and supplementary materials. Several-storey offices and dwellings were studied. The functional unit was defined as one average m² of floor area during the lifetime of the building. Inventory data were elaborated for concrete and steel production, the building site, service life, demolition and final disposal. Parameters included were raw material use, energy use, emissions to air, emissions to water and waste generation. The inventory results were presented and evaluated as such, in addition to an interpretation by using three quantitative impact assessment methods. Parameters that weighed heavily were use of fossil fuels, CO₂, electricity, SO_x ² NO_x ² alloy materials and waste, depending on what assessment method was used. Over the life cycle, building production from cradle to gate accounted for about the same contribution to total environmental loads as maintenance and replacement of heat losses through external walls during service life, whereas demolition and final disposal accounted for a considerably lower contribution.     

Resource Consumption of New Urban Construction in China

The volume of China's recent additions to its urban-built environment is unprecedented. China now accounts for half of all new building area in the world. Increases in building stocks of all types have occurred during an extended period of accelerated growth of the national economy. This expansion promises to continue through 2030. As a result, the rapid conversion of land from low-density agricultural and light manufacturing to new urban zones of high density and material-intensive commercial and residential buildings has consumed enormous quantities of domestic and imported resources and has irreversibly altered the Chinese landscape. This article examines the consumption of material resources dedicated to Chinese building construction through a survey and analysis of the material intensity of three major building types. This provides a basis for outlining the emerging life-cycle issues of recent additions to the built environment and of continued construction. With this as the starting point, the field of industrial ecology can work toward formulating strategies for a circular economy that include a resource-efficient urban China.     

不同SSP-RCP情景下中国生态系统服务价值评估

定量评估生态系统服务价值是人类合理利用和管理生态系统的重要依据,未来气候情景下土地利用变化模拟及其对生态系统服务价值的影响评估对于区域生态系统服务管理、开展生态功能区划及减缓和适应气候变化等方面具有重要意义。基于最新IPCC共享社会经济路径(SSPs)和典型浓度路径(RCPs)的科学组合情景模拟得到的土地利用情景数据,对2020—2050年我国生态系统服务价值进行估算,并对2050年生态系统服务间的权衡与协同关系进行讨论,主要得到以下结论：生态系统服务价值(ESV)在2020—2050年表现为SSP1-RCP2.6>SSP2-RCP4.5>SSP3-RCP6.0,SSP1-RCP2.6情景下2020年ESV为12.39×10⁴亿元,2050年ESV为12.34×10⁴亿元;SSP2-RCP4.5情景下2020年ESV为12.17×10⁴亿元,2050年ESV为12.11×10⁴亿元;SSP3-RCP6.0情景下2020年ESV为12.02×10⁴亿元,2050年ES...     

Indoor and outdoor pollen concentrations in private and public spaces during the <Emphasis Type="Italic">Betula</Emphasis> pollen season

Although the number of studies of pollen concentrations inside and outside buildings is increasing, little is known about the efficiency of penetration of pollen from outdoor to indoor air, and further. We studied indoor and outdoor pollen concentrations in the town of Lappeenranta and in the municipality of Rautjärvi in SE Finland from May 3–23, 2004, i.e. throughout the Betula pollen season, and assessed the risk of exposure to pollen grains. Pollen concentrations were measured inside and outside a block of flats, a detached house, and the regional central hospital, using rotorod-type samplers; in the town of Joutseno data were compared with Burkard counts. Outdoor concentrations of Betula pollen grains ranged between low and abundant (0–855 grains m^?3). The corresponding indoor concentrations near the main front doors varied from low to moderate (0–17 grains m^?3) in the central hospital and were low (<10 grains m^?3) in both residential buildings. Indoor concentrations further from the main front door were low (<10 grains m^?3) at all study sites. The concentrations of Betula pollen decreased substantially from outdoors to indoors, and further toward the centre of the building, probably indicating relatively poor penetrating properties of the pollen grains and/or the short-lived presence of pollen grains in indoor air. The concentrations of Betula pollen inside the buildings during the peak flowering period were mostly at a level barely inducing reactions even in the most sensitive persons.     

以材料“创造”土地？——中国城市化进程的一个重要特征

中国快速城市化进程的一个重要特征是以土地为载体,通过大量投入钢铁、水泥等建材大规模修建城市建筑和基础设施,创造出大量的城市生产和生活空间。利用1985—2010年中国省级行政单元城市建成区总面积、城市居住用地总面积、城市住宅总面积和城市住宅建筑材料总使用量等数据,识别城市扩张模式,揭示中国城市化进程中土地、建筑面积及其构筑材料三者间的关系。研究表明2000年是中国城市扩张的重要分界点,2000年之前中国各省份的城市建成区总面积、城市住宅总面积和城市住宅建筑材料总使用量均较小且省份间差异不大,2000年之后三者迅速增长且省份间差异逐渐扩大。在地区尺度上,三者均呈现东部地区最高、中部次之、西部最低的特点,地区内部差异则表现为东部地区最大、西部次之、中部最小的特征。大多数省份的城市住宅总面积及其构筑材料总量随着城市建成区的扩张而增长,表明城市在发展初期以扩大建成区和水平扩张为主。随着城市化水平的不断提高,城市内部空间重组和用地置换导致高层建筑逐步替代了原有的单层或低矮建筑,城市扩张的方向由依赖土地的水平扩张转向以大量使用建筑材料为基础的垂直扩张,使得许多省份的城市住宅总面积逐渐超过辖区内居住用地总面积。这种以建筑材料"创造"出更多"土地"的城市垂直扩张在满足人们对城市生产和生活空间需求的同时,有利于节约土地资源和保护生态空间,但需要以消耗更多的建筑材料并承担建筑材料在开采、制造、运输、使用和废弃过程中所造成的环境影响为代价。