“凿户牖以为室，当其无，有室之用”。地面建筑物是人类生产与消费活动的物理载体和服务提供者，其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，其新建和拆除是各种建材资源在地球表面物质能量迁移转化的过程，例如，建筑材料已经成为继水资源之后第二大输入城市系统的物料，对生态环境有着直接或间接的影响。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。因此，系统分析城市建筑代谢的过程与机理，模拟与识别建筑流量-存量演变规律及其资源环境影响，对于减轻城市化过程的资源环境压力，推进资源循环与高效利用，提升废弃物处置效率，实现可持续城市管理具有重要的理论与实践管理意义。

本论文基于隐喻视角将生命代谢过程的基本理论（同化作用与异化作用）引入城市建筑代谢研究，基于结构与功能辩证关系，提出了同质代谢、异质代谢，拓展了现有城市建筑代谢的概念与分析框架。基于此框架，融合多源数据类型，集成地理信息系统（GIS）、自下而上的物质存量与流量核算方法以及系统动力学模拟方法，借助大数据挖掘与分析技术等，开发了建筑存量高空间分辨率核算模型，识别了中国城市尺度下建筑存量的材料组成、重量、空间分布以及在三维扩张过程中生长机制；刻画了城市建筑代谢过程中同质资源（建筑材料）、异质资源（水、能等）流量的交互耦合特征；系统模拟了建筑系统同质资源流量-存量的动态变化过程及其资源环境响应。论文的主要研究内容和结论如下：

（1）类比生命体的同化与异化作用，基于结构-功能辨证关系，提出了同质代谢、异质代谢概念，在统一框架下理清了其相互作用关系。同质代谢是指传统意义上建筑结构的构筑引发的建筑材料（例如钢铁、水泥等）的投入、使用和废弃的过程；异质代谢是指建筑服务功能发挥过程中，建筑存量需要耦合异质资源（例如水、能等）消耗从而引发代谢。两种代谢过程共同维系和支撑了城市建筑系统的结构和功能。

（2）开发了基于大数据挖掘技术的高空间分辨率建筑存量核算模型，打开了城市建筑存量的空间黑箱，量化了城市各种建筑材料存量结构特征与空间格局，探讨网格尺度下建筑存量与社会经济属性之间的响应关系。研究发现，北京市现有建筑高度呈现出“中心凹陷式”的整体特征，而建筑密度却呈现“中心凸起”特征，二环以内建筑高度最低但密集度最高。建筑高度、密集度与建筑结构共同影响城市建筑材料存量的结构与分布。北京市2019年建筑材料存量共21.59亿吨，主要集中在六环以内，其中，2000年之后新建存量占总存量的82.14%。就材料组成而言，沙子、砖、砾石和水泥等依次占比29.91%、25.07%、24.75%以及12.19%，呈现环境的“混凝土化”特征。就建筑年龄而言，从内向外各环路建筑呈现出“年轻化”的空间演替规律，这与北京圈层式的城市化发展路径密切相关。

（3）耦合自下而上存量核算方法与GIS工具刻画了我国55个城市建筑存量空间特征，识别了城市建筑存量生长机制，解析城市三维扩张过程横向与纵向生长的速度，验证了建筑代谢过程的异速生长定律。建筑高度与密集度的空间特征，反映了不同城市的生长机制，进而影响了城市建筑材料存量的空间格局。在中国城市化进程中，城市建筑系统的横向和纵向同时（扩张）生长，但是纵向扩张的速度显著高于横向扩张。城市内部空间重组和用地置换，导致以大量使用建筑材料为基础的垂直扩张速度大于依赖土地资源的水平扩张速度，用 “材料”置换“空间”特征显著。同时也揭示与验证了异速生长定律在城市建筑代谢领域的适用性。

（4）基于自下而上的物质流分析方法，定量核算了40年来北京市住宅建筑的代谢过程及其资源环境影响，刻画不同城镇化阶段同质与异质资源代谢特征及其变化规律。城市住宅建筑系统的存量与同质资源消耗流量之间耦合关系呈现不同的阶段性特征，北京市从1978-2005年呈现强耦合特征转变为2005-2018 的脱钩关系并持续强化。在同质资源先耦合后脱钩的同时，异质性资源-能源的耦合性却不断强化，异质性资源-水的消耗呈现先强化后弱化的趋势。但同质与异质资源消耗引起的二氧化碳排放总量呈现出“S”形曲线，与建筑存量累积趋势一致，说明北京建筑代谢进入存量维护与功能发挥阶段。

（5）基于Stella建模平台，综合考虑不同建筑结构组成，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，分析了钢铁的循环策略。在基准情景下，北京市住宅建筑新建面积流量在2005年已达到峰值（3.02E +7 m²），然后呈周期性变化并于2079年达到第二个峰值（1.65E+7m²）；就建筑存而言，模拟结果显示1980-2030年建筑存量增长幅度最大，并于2059年达到饱和（8.79E+8m²）；从后端来看，北京将于2079年遇到第一个建筑垃圾产生量高峰（2.47E+7吨）。若实施有效的城市建筑垃圾资源化利用政策，2020-2100年累积原生钢铁需求量将减少约71.25％。进一步解析原生钢铁需求量动态变化，短寿命情景下，原生钢铁需求量于2060年以后接近于零，表明北京市居民住宅建筑系统的钢铁需求量实现了闭合循环；中等寿命情景的二次钢铁不仅满足未来北京市住宅建筑系统新建活动对钢铁的需求，甚至有盈余；其中，基准情景下2075-2100年累积盈余钢铁量91.53万吨。

本论文的创新点主要体现在三个方面：（1）本文从建筑存量的结构性累积和功能性发挥双重解构思路出发，基于同质与异质代谢过程构建了城市建筑代谢新的概念体系与分析框架。与传统的采用线性输入-输出代谢研究相比，该框架能够更立体更全面的揭示城市建筑代谢过程中引发的同质/异质资源环境消耗，从而可以为城市建筑代谢研究者提供新的研究视角和思路；（2）集成物质存量分析（MSA）与地理信息技术（GIS）方法，借助大数据挖掘与多源数据融合技术，开发GIS-MSA耦合模型，打开了城市建筑存量的空间黑箱，构建了中国城市尺度建筑存量高空间分辨率数据库，刻画了城市建筑存量的空间分布、组成和特点；（3）从时空两个维度分析了城市建筑代谢的演变机理，识别中国城市建筑存量的生长机制，验证了建筑系统代谢的异速生长定律，揭示了城市建筑流量/存量动态变化规律及其资源环境影响。本研究可为资源需求预测、建筑存量优化、城市矿山开发等可持续城市管理提供科学、定量化的依据。

“The house is treated as a room, but when it is not, there is room for it”. Building stock on the ground are the physical carriers and service providers of human production and consumption activities, and its accumulation and renovation are the typical characteristics and inevitable results of the urbanization process. The material and energy flow between the urban building system and hinterland environment interacts with each other at different levels. Construction and demolition activities are the process of material-energy transfer and transformation of various construction materials resources on the earth's surface. For example, construction materials have become the second largest input after water resource. The resources and environmental pressure associated with the exchange between the urban building stock and hinterland environment make it to be a hot issue in the field of urban metabolism research．Therefore, the systematic analysis of the process and mechanism of urban building metabolism, simulation and identification of the flow-stock evolution law and its impact on resources and environment will reduce the pressure on resources demand and the environment impact, promote resource recycling and efficient use, and improve waste disposal efficiency. All of these are essential to achieve sustainable urban management.

Based on the perspective of metaphor, this study introduces the basic theories of life metabolism (assimilation and alienation) into the study of urban building metabolism, and expands the existing concept and analytical framework. Based on this framework, integrating bottom-up accounting methods and tools of geographic information system, besides, using big data mining and analysis techniques, system dynamics simulation methods to develop a high-spatial resolution accounting model for the building stock. With that, we described the material composition, weight, spatial distribution and growth mechanism of the building stock at the urban scale of China, as well as the growth mechanism during the three-dimensional expansion process. Besides, we also identified interaction coupling characteristics of homogeneous resources (construction materials) and heterogeneous resources (water, energy, etc.) flow with building stock during the metabolic process since 1978. Finally, dynamic modeling of stock and flow in an urban residential building system was developed to simulate the resources demand and its resource environment response. The main conclusions are as follows:

 (1) Based on the structure-function perspective and the analogy of the assimilation & dissimilation of living organisms, we expanded the analytical framework of building metabolism. That is, building metabolism includes homogenous metabolism and heterogeneous metabolism, and proceed at the same time, either. Homogeneous metabolism refers to the process of input, use and abandonment of building materials (such as steel, cement, etc.) caused by the construction of building. Heterogeneous metabolism refers to the process of building service functions provided in which the building stock needs to be coupled with heterogeneity resources (such as water, energy, etc.).

(2) A high spatial resolution building stock accounting model based on big data mining technology was developed to open the spatial black box of urban building stock, quantify the building characteristics and spatial pattern of various urban construction materials stock, and then discuss the relationship between building stock and socioeconomic attributes (e.g., urban population and GDP) at the grid-level. The study found that the building heights in Beijing urban area overall present a “central recessed” feature, while the building density presents a “center protruding” feature within the second ring road. Buildings within the second ring road have the lowest height but the highest density. Building height/density and building structure affect the structure and distribution of urban construction material stocks together. The total construction materials stock in Beijing in 2019 was 2.16 billion tons, of which the newly built stock after 2000 accounted for 82.14%. In terms of material composition, sand, bricks, gravel and cement accounted for 29.91%, 25.07%, 24.75% and 12.19%, respectively, showing the "concrete" characteristics of the urban environment. In terms of building age, the buildings on the ring road from the inside to the outside show a "younger" spatial succession law, which is closely related to the development path of Beijing's circle-style urbanization. On the 1km grid-level, the intensity of human activities is correlated significantly with material service capacity. Besides, some correlation between material stock and GDP can be better understood at a refined level in Beijing.

 (3) Integrating bottom-up stock accounting method and GIS method to characterize the building stock of 55 sample cities in our country, identify the growth mechanism of urban building stock, analyze the speed of horizontal expansion and vertical growth during the three-dimensional expansion of the urban area, and verify the allometric scaling in urban building system. The spatial characteristics of building height and building density reflect the growth mechanism of different cities, which in turn affects the spatial pattern of the stock of construction materials. Under the process of urbanization in China, the horizontal and vertical growth of the urban building system (expansion) at the same time, but the speed of vertical expansion (growth) is obviously higher than that of horizontal expansion. The reorganization of urban interior space and the replacement of land use have resulted in the vertical expansion rate based on the massive use of construction materials being faster than the horizontal expansion rate relying on land use, and showing characteristic of “creating land by materials”. At the same time, it reveals and verifies the applicability of the law of allometric growth in the field of urban building metabolism.

(4) Based on the bottom-up material flow analysis method, the metabolic process and resource environmental impact of residential buildings in Beijing over the past 40 years are quantitatively calculated, and the metabolic characteristics and changes of homogeneous and heterogeneous resources in different urbanization stages are described. The Beijing case study shows that the coupling relationship between the stock of the urban building system and the consumption flow of homogeneous resources presents different phase characteristics. From the strong coupling characteristic in 1978-2005 to the decoupling relationship in 2005-2018 and continues to strengthen. While homogeneous resources are first coupled and then decoupled, the coupling between heterogeneous resources-energy is continuously strengthened, and the consumption of heterogeneous resources-water presents a trend of first strengthening and then weakening. However, the total amount of carbon dioxide emissions caused by the consumption of homogeneous and heterogeneous resources has been saturated and even has a downward trend, indicating that Beijing's building metabolism has entered stock maintenance and functioning stage.

(5) Using Beijing as the case city, a system dynamic model under Stella platform, was developed to simulate the urban residential building flow changes and related steel demand as well as C&D waste generation from 1949 to 2100. Results indicate that the residential building flows and related stocks of Beijing will largely vary depending on the scenarios. Under the baseline scenario, the construction flow reached the second peak in 2079 (1.65E+7m²), while the building stock is estimated to saturate in 2059 with a total building floor area of 8.79E+8m², and the largest demolition activity is expected in 2079 with a demolished floor area of 1.65E+7m². Overall cyclical dynamics are observed for construction and demolition flows under middle and long-lifetime scenarios, but not prominent for short-lifetime scenarios. If effective urban mining strategies are implemented, then more than 70% of future primary steel demand can be satisfied by recycled steel from C&D waste for baseline scenario. The results obtained in this study illustrate the significant resource and environmental saving potential of prolonging the building lifetime and strengthening recycling practices, and highlight the great need of effective policy intervention for waste management infrastructures planning in advance.

The innovations of this paper can be summarized as follows: (1) This study starts from the dual concept of construction materials accumulation and service function provision of the building stock, and expands the concept and analysis framework of urban building metabolism. Compared with the traditional linear input-output metabolism research, this framework can reveal the homogeneous/heterogeneous resource and environmental consumption caused by the metabolic process of urban buildings more three-dimensionally and comprehensively, and then providing new research perspectives and ideas for urban building metabolism researchers; (2) In terms of research methods, integration of material stock analysis (MSA) and geographic information technology (GIS) methods, with the help of big data mining and multiple data fusion technology, we developed a GIS-MSA coupling model, and opened up the urban building stock and then built a high-resolution database of the Chinese urban building stock, which depicts the spatial distribution, composition and characteristics of the urban building stock; (3) We analyzed the evolution mechanism of urban building metabolism from the time and space dimensions, identified the growth mechanism of China's urban building stock, verified the allometric growth law of urban building system, and revealed the dynamic changes of urban building flow/stock and its impact on resources and environment. This research can provide a scientific and quantitative basis for sustainable urban management such as resource demand forecasting, building stock optimization, and urban mining development.